NBSIR 73-207

Chemical Kinetics Data Survey

VI: Photochemical and Rate Data for

Twelve Gas Phase Reactions of

Interest for Atmospheric Chemistry

R. F. Hampson, Editor

D. Garvin, J. T. Herron, R. E. Huie, M. J. Kurylo,

A. H. Laufer, H. Okabe, M. D. Scheer, and W. Tsang

Physical Chemistry Division

Institute for Materials Research

National Bureau of Standards

Washington, D. C. 20234

August 1973

Interim Report

QC

. U56 iatic Impact Assessment Program, Department of Transportation,

no. 7 3- 3 1 Ordnance Systems Command, ORD 3311, Department of the Navy

207 ^e of Standard Reference Data, N.B.S.,

;ures for Air Quality, N.B.S.

NBSIR 73-207

CHEMICAL KINETICS DATA SURVEY

VI. PHOTOCHEMICAL AND RATE DATA FOR

TWELVE GAS PHASE REACTIONS OF

INTEREST FOR ATMOSPHERIC CHEMISTRY

R. F. Hampson, Editor

D. Garvin, J. T. Herron, R. E. Huie, M. J. Kurylo,

A. H. Laufer, H. Okabe, M. D. Scheer, and W. Tsang

Physical Chemistry Division

Institute for Materials Research

National Bureau of Standards

Washington, D. C. 20234

August 1973

Interim Report

Prepared for Climatic Impact Assessment Program, Department of Transportation,

Naval Ordnance Systems Command, ORD 3311, Department of the Navy

Office of Standard Reference Data, N.B.S.,

and

Measures for Air Quality, N.B.S.

U. S. DEPARTMENT OF COMMERCE, Frederick B. Dent, Secretary

NATIONAL BUREAU OF STANDARDS, Richard W. Roberts. Director

Table of Contents

Page

Abstract 1 Introduction (Includes revisions of recommendations in previous \

reports)

Data Sheets

H + H

2 02 + Products M. D. Scheer 4

HNO + hv R. F. Hampson 7

HO + 15L 0 -> H0

2 + H

2 0 M. J. Kurylo 9

HO + NO + M -> HN0

2 + M W. Tsang 15

HO + N0

2 + M -> HNO^ + M W. Tsang 21

NO + hv H. Okabe, R. F. Hampson^

D. Garvin 33

NO + U + M -> JN0 2 + M K. E. Huie, J. T. Herron JJ

N0 o + hv

2

R. F. Hampson, D. Garvin 59

N0 o + 0 -> NO + 0o R. E. Huie, J. T. Herron 79

N0

2 + 0 + M -> N0

3 + M R. E. Huie, J. T. Herron 85

N

205 + hv R. F. Hampson 93

°2 + hV A. H. Lauf er 98

Appendix A. Reactions of Potential Interest for the Chemistry of the

Stratosphere.

Appendix B. Conversion Tables: Rate Constants, Energy Units and Optical

Absorption Coefficients.

Appendix C. Errata to NBSIR 73-203 and NBSIR 73-206.

i

Chemical Kinetics Data Survey

VI. Photochemical and Rate Data for Twelve Gas Phase

Reactions of Interest for Atmospheric Chemistry

Abstract

Photochemical and rate data have been evaluated for twelve gas

phase reactions of interest for the chemistry of the stratosphere. The

results are presented in data sheets, one for each reaction. For each

reaction the data are summarized. A preferred value is given for the

rate constant or the primary quantum yield and photoabsorption cross section

.

Key words: atmospheric chemistry; chemical kinetics; data

evaluation; gas phase reaction; optical absorption cross section;

photochemistry; quantum yield; rate constants.

Introduction

This report presents evaluations of chemical kinetic and photochemical

data for twelve gas phase reactions. It is the sixth IP a series. The

objective of the work and a description of the general format of a data

sheet including explanatory material regarding general conventions for the

presentation of data have been given in the introductory sections of

two previous reports: NBS Report 10692 (January 1972) and NBS Report

10828 (April 1972).

The evaluations in these two reports have been updated recently and

will be published in "Survey of Photochemical and Rate Data for TwentyEight Reactions of Interest in Atmospheric Chemistry", R. F. Hampson,

editor. J. Phys . Chem. Ref . Data 2_> #2(1973). For some reactions, a change was made in the recommended value of the rate constant, quantum

yield or absorption cross section. These changes are summarized in the

following tables.

1
Table 1. Revised Recommended Values for Reactions Evaluated in

NBS Reports 10692 and 10828

RATE CONSTANTS

Reaction k/ cm" molecule ^ T/K Alog k

H + HNO •+ H

2 + NO 7 X io"

12

2000 ±0. 3

HNO + HO » H

2

0 + NO 7 X io"

11 1600-2100 ±0. 7

HN0

2 + HO * H

2 0 + N0

2

No recommendation

HN0

3 + HO + H

2 0 + N03

6 X

-13

10 exp(-400/T) 300-650 ±0. 5

HO + 0

3

+ H0

2 + 0

2 1.6 X

-12 , , s 10 exp(-1000/T) 220-450 ±0. 3

H0

2 + H0

2 H

2

0

2 + 02

3 X 10

_11

exp (-500/T) (a) 300-1000 ±0. 3(b.

H

2 0 + NO + N0

2 * 2HN02

< 1.1 X 10~ 55

(c) 300

H

2

0 + N

20

5 2HN03

< 1 X io

-20

300

H

20 + O^D) -> 2H0 X io

-10

J-U 300 ±0. 1

H

2

0

2 + NO + HO + HN02

X io"

20

300

N°2 +

°3 ^ N°3 + °2 5 X io" 17

298 ±0. 2

N

2 0 + O^D) + N

2 + 0

2 1.1 X IO"

10

io"10

300 ±0. 1

-* 2NO 1.1 X 300 ±0. 1

0 + 0

3

> 20

2

1.9 X 10

_11exp(-2300/T) 200-1000 ±0. 1

0

2

( 1

A) + M -> 0

2 + M < 2 X

-20

10

ZU

(M=N

2

) 300

(a) -d[H0

2 ]/dt = 2k[H02

] 2

(b) Uncertainty in log k increases to ±1 at 1000 K.

2 (c) -d[N0

2 ]/dt = k[N0] [N02

] [H 0] . The experimental data show a second

order dependence of rate on [H

2 0]. Value for k is for a surface

reaction. This is adopted as the upper limit for the gas phase

rate constant.

2
Table 1 (Continued)

PHOTOCHEMICAL DATA

Quantum yield,

HNO + h\) -»

1111* W ^

1 11 V HO + N0

2 no recommendation

0 + hv(uv)

j

-» 0(

1

D) + °2 (3 V

0

- 0(

3

P) + 0

2 (singlet)

0 * o^d) + 0

2

( XA) 10

Wavelength

A , nm

< 350

310-350 < 310

250-310

>310

Also, the newer values of the absorption cross section for nitric

acid by Johnston and Graham (J. Phys . Chem. 77, 62 (1973)) are now the

recommended values. .

Note concerning the 0^ quantum yields

The behavior of 0(O^D) near X = 310 nm is currently under study in

several laboratories. These should provide a better definition

of 0(O(^D) in the critical region near the thermochemical threshold.

A reanalysis of the matter will appear in a later publication in this

series

.

3
„, . i , H + H o 0 o Chemical Kinetics Data Survey 2 2

The Reaction of H with

1. Two channels are possible for this reaction; they are

H + H

2 0

2

-» H

2 + H0

2 k

H + H

2 02 H

2 0 + HO k

2

2. ^298 (1) = " 61 ± 8 kj/mo1 ("14.5 ± 2 kcal/mol) (a)

AH°

gg

(2) = -284 kj/mol (-68.0 kcal/mol) (a)

log

10

K

eq.

(1) = °' 342 + 3 ' 26 ( 100°/T) (b)

log

1Q

K (2) = 0.877 + 14.98 (1000/T) (b)

3 . Data

The available rate data have been presented and evaluated by

Baulch, Drysdale, Home and Lloyd (c) . *n their 1972 review, they

recommended the expression k^ = 2.8 x lO - -^ exp (-1900/T) cm^

molecule s

^ from 300 to 800 K and made no recommendation for k

2

.

There have been no more recent measurements

.

Albers et al (d) measured the total rate of removal of D atoms

in a discharge-flow reactor from 294 to 464 K with 5-8 torr H

2 02 and

added 0 atoms to suppress the chain decomposition initiated by OH . D

atoms were monitored by ESR and mass spectrometry. They estimate that

k

x /k

2 m 10 for D atoms at 421 K. Also they find k

^

/k

^ = 0.43

at 375 K. They give the result that k^0^ + k

2 ^ = 1.2 x 10" U

exp

(-4200/RT) cm

3 molecule~ 1 s"1

. (294-464 K)

.

Baldwin et al (e) studied the decomposition of H

2 02 in the

presence of H

2 from 713-773 K. They report k^/k

2 to have the value

0.143 over this temperature range (note: in their abstract this is

incorrectly given as 0.125). Also they measure the ratio k

2 /k^ where

(3) is H + 0

2 + M -* H0

2 + M. From this ratio and their previously

measured values of k

3 /k

4

where (4) is H + 0

2

-» HO + 0 they derive

4
H 4- H

2 0

2

values of k„/k. . Baulch et al (c) use the values /k„ and k„/k.

2 4 1224

in (e) with their own recommended expression for k^ to obtain values

of k^ • (Note: Because Baulch et al used the value of k^/k^ in

Baldwin's abstract, the calculated values of k^ given on p. 212 0 f (c)

should be increased by 1470 ; however this will not seriously affect

their evaluation)

4 . Preferred value

k = 2.8 x 10" 12

exp (-1900/T) cm

3 molecule

_1

s _1

(300-800 K)

uncertainty: factor of two

no value is recommended for k

5 . Remarks

The recommendations of Baulch et al have been adopted. The

-9 3 -1 -1

value derived there for = 3,7 x 10 exp (-5900/T) cm molecule s

as noted there can not be recommended with any confidence because

of the unreasonably high value of the pre-exponential factor.

By extrapolation, ^ at stratospheric temperatures (220 K) is

estimated to be 5 x 10" 16 cm

3 molecule

_1

s

~ l

. From these expressions k^^l at 220K is estimated to be 10~ 5

, subject

to a large uncertainty.

References

a) D. D. Wagman et al, NBS Technical Note 270-3 (Jan. 1968).

b) V. N. Kondratiev, "Rate Constants of Gas Phase Reactions -

Reference Book," R. M. Fristrom, editor. National Technical

Information Service, Springfield, Virginia COM-72-10014 (Jan.

1972) .

2

5
H 4- Ho 0

2

3

c) D. L. Baulch, D. D. Drysdale, D. G. Home, A. C. Lloyd,

"Evaluated Kinetic Data for High Temperature Reactions

volume 1, Homogeneous gas phase reactions of the H^-O^

systems," Butterworth & Co. London (1972).

d) E. A. Albers, K. Hoyermann, G. Gg. Wagner, J. Wolfrum,

13th Combustion Symposium 81 (1971).

e) R. R. Baldwin, D. Brattan, B. Tunnicliffe, R. W. Walker,

S. J. Webster, Combustion and Flame 15_, 133 (1970).

M. D. Scheer

September, 1972

6
HN0

2 + hv

PHOTOCHEMISTRY OF HNO,

1 . Primary Photochemical Transitions

Reaction

HN0

2

-> OH + NO

+ H + NO,

-» HNO + 0

AHg

kj/mol

202

326

423

kcal/mol

(48)

(78)

(101)

(AHg values from [a] except AHg (HNO) from [b])

2. Data

X threshold (nm)

590

3 70

280

The absorption spectrum of HN0

2 vapor in the region 300-400 nm, has been

reported and partly analyzed ( ref [c] and references cited therein ).

It consists of a series of diffuse absorption bands which showed no

fine structure when photographed on a 20-foot grating spectrograph

with a resolving power of 150,000. Fig. 1 (from [c]) shows the

absorption spectrum of HN0

2 at 25°C.

HON 0

33 32 31 30 29 28 27 26 25 ~/ n ~3 -1

V/10 cm

Fig. 1 The absorption spectrum of HONO at 25 C.

Reproduced by permission of the National Research Council of Canada

from the Canadian Journal of Chemistry, 40, 2057-2065 (1962)
HN0

2 + hv 2

No absorption coefficients nor quantum yields have been published.

Preliminary measurements (H . Johnston, private communication) on

NO + NO2 + l^O 2 HNO2 equilibrium mixtures provide a scale for

figure 1, good to a factor of 1.5 to 2. The absorption cross

sections for peaks B and E, averaged over a 1 nm wavelength interval

-20 -20 2 -1 were 10.7 x 10 and 3.8 x 10 cm molecule respectively.

The only related data on absorption coefficients are for HNO^ in

aqueous solution [d]. For HNO^ in 0.05 normal HCl, there are a

series of bands from 380 to 320 nm, with the maximum value of the

decadic molar extinction coefficient equal to 50 liter mol ^ cm

^

-19

at approximately 371 and 358 nm. (abs . cross section = 1.9 x 10

2 cm ) . These values obtained in a polar solvent are not recommended

for use in calculating the absorption of HNO^ in the gas phase.

3 . Preferred values

No values are recommended for the absorption coefficient or

the quantum yield.

References

[a] D. D. Wagman et al, NBS Technical Note 270-3 (Jan. 1968).

[b] D. R. Stull and H. Prophet, "JANAF Thermo chemical Tables, 2d.

Ed." Nat. Stand. Ref. Data Ser., Nat. Bur. Stand. (U.S.),

37 (June, 1971).

[c] G. W. King and D. Moule, Can. J. Chem. 40, 2057 (1962).

[d] G. Kortum, Z. Phys. Chem. B43, 418 (1939).

R. Hampson

November 1972

8
HO + H

2 0

2 Chemical Kinetics Data Survey

The Reaction of HO with H„0

Reaction

HO + H

2 0

2

-> H0

2 + H2 0

(298) = -124.3 kj mol

-1

(-29.7 kcal mol' 1

) (a)

loSlO K

eq

= -0.329 + 6.612 (1000 /T) (j)

Data

The available data prior to 1972 have been described and evaluated

Baulch et al [h] and by Drysdale and Lloyd [i]. in these reviews

in 1972 and 1970, they recommended the expression =

1.7 x 10" 11

exp (-910/T) cm

3 molecule" 1 s"

1 from 300 to 800 K.

Upper and lower limits for k^ at 298 K have been derived from

studies employing flash photolysis [b] and electric discharge

Absolute values of k^ over the temperature range 307 - 462 K

have been determined in flash photolysis studies by following

the OH decay by kinetic spectroscopy.

Rate ratio data at higher temperatures extends the range. A

k^/k

2 ratio was determined at 798 K using the thermal decomposition of H o 0 in the presence CO [d].

[c] of H

2 0

2

.

CO + HO -» CO- + H (2)
HO + M

2 02

The rate relative to reaction 3,

HO + H„ -> H + H

2 0 (3)

has been determined between 700 and 800 K by examination of

the inhibition of the second explosion limit of the system

by #2^2 f e -^' studi- es °f the decomposition of ^2®2 ^ n t*16

presence of H

2 in boric acid coated vessels [f] and from studies

of the H

2 /02 /N

2 system [g].

b . Recent measurements

There has been only one measurement involving the rate of

this reaction since the 1972 review by Baulch et al (h)

.

Quantity Measured

k

x /k

2 = 8.13 ± 0.56

where k

2

: HO + CO -> C0

2 + H

Sys tern

Photolysis of HgO (0.94 torr)

at 254 nm. in presence of 0

2

(5.4 torr) and CO (3-32 torr).

Measured initial rate of formation

of C0

2

.

GORSE. VOLMAN 1972 (k)

Preferred Value

k

x = 1.7 x 10

11

exp(-910/T) cm

3 molecule" 1

s _1

for 300 < T < 800.

k

l (300 K) = 8.2 x 10

13 cm

3 molecule 1 s~

1

. This is the evaluation

given in refs [h, i]. It fits the measured data within 50%.

10
HO 4- H

2 02 3

5 . Remarks

Reaction 1 is a simple H atom abstraction

HO + H-0

2H -» H

2 0 + H0

2 and is the only interaction expected in this system.

The evaluation relies heavily on the data of Greiner which are

the only absolute rate measurements available. The flash

photolysis study is subject to some uncertainty due to the

method of temperature measurement. The temperature was varied

by changing inert gas pressures thereby lowering the effect of

flash heating. This coupled with the normal experimental uncertainties gives a reliabity factor of approximately 2 to the

data. Thus, the expression given above probably predicts the

value for k- within a factor of 2 over the temperature range

298 to 800 K. At stratospheric temperatures 200-240 K the

uncertainty is considerably larger (probably at least a factor

of 4) . Thus a number of lower temperature measurements are in

order

.

11
HO + H

2 0

2 4

A value of can be derived from the recent relative rate

measurement in ref . (k) by selecting a value for k^ : HO + CO ->

C0„ + H. For the room temperature value of k^ we select the recent

-13 3 direct measurement of Stuhl and Niki (&) : k^ = 1.35 x 10 cm

molecule ''"s • This result has been confirmed quite recently in a

study using a completely different technique (m) . Using this value,

-13 3 -1-1

we derive the value k^ = (11 ± 3) x 10 cm molecule s from

the ratio measured in (k) . We consider this to be in substantial

-13 3 -1 -1

agreement with the value k^ (300 K) = 8.2 x 10 cm molecule s

recommended in Section 4. The combined uncertainties in the

measured values of (k^/k^) and k^ and the complexity of the

mechanism used in (k) do not justify changing the recommended value

of k... Alternatively, one can use for k

? the expression k^ =

5.1 x lO

-13

exp (-300/T) cm

3 molecule'^s

1 recommended by Wilson in

his recent lengthy review of hydroxyl radical reaction kinetics (n)

: 2

-13 3 -1-1

This expression gives k„ = 1.88 x 10 cm molecule s , which value,

-13

when combined with the ratio measured in (k) gives = 15 x 10

3 ,

i - 1 -

1

cm molecule s

References

a) D. R. Stull and H. Prophet, " JANAF Thermo chemical Tables, 2d.

Ed." Nat. Stand. Ref. Data Ser., Nat. Bur. Stand. (U.S.), 37

(June 1971)

.

b) N. R. Greiner, J. Chem. Phys . 45, 99 (1966); ibid, 46, 2450

(1967) (erratum); superseded by J. Phys. Chem. 72, 406 (1968).

c) S.N. Foner and R. L. Hudson, J. chem. Phys. 36, 2681 (1962).

d) D. E. Hoare, Proc. Roy. Soc. (London) A291, 73 (1966).

12
HQ + H

2 0

2 W. Forst and P. A. Giguere, J. Phys. Chem. 62, 340 (1958), R. R.

Baldwin and L. Mayor, Trans. Faraday Soc. 56, 80 and 103 (1960),

R. R. Baldwin, P. Doran and L. Mayor, Symp. Combust 8th, 103

(1962) .

R. R. Baldwin and D. Brattan, Symp. Combust 8th, 110 (1962), R.

R. Baldwin, D. Jackson, R. W. Walker and S. J. Webster, Symp.

Combust 10th, 423 (1965).

R. R. Baldwin, D. Jackson, R. W. Walker and S. J. Webster, Trans.

Faraday Soc. 63, 1676 (1967).

D. L. Baulch, D. D. Drysdale, D. G. Home, A. C. Lloyd,

"Evaluated Kinetic Data for High Temperature Reactions volume

1, Homogeneous gas phase reactions of the H2~ ®2 system",

Butterworth & Co., London (1972); also in D. L. Baulch, D. D.

Drysdale and A. C. Lloyd, High Temperature Reaction Rate

Data, Report No. 3 (1969), Dept. of Physical Chemistry, The

University, Leeds, England.

D. D. Drysdale and A. C. Lloyd, Oxidation and Combustion

Reviews, 4, 157 (1970).

V. N. Kondratiev, "Rate Constants of Gas Phase Reactions -

Reference Book," R. M. Fristrom, editor. National Technical

Information Service, Springfield, Virginia COM-72-10014

(Jan. 1972).

13
HO + H

2 0

2

6

k) R. A. Gorse and D. H . Volman, J. Photochem., 1, 1-10 (1972).

I) F . Stuhl and H. Niki, J. Chem. Phys . 57, 3671 (1972).

m) A. A. Westenberg and N. de Haas, J. Chem. Phys. 5_8, 4061 (1973).

n) W. E. Wilson, Jr., J. Phys. Chem. Ref. Data I, 535 (1972).

July. 1972

Revised July, 1973

M . J . Ku ry 1

o

14
Chemical Kinetics Data Survey

The Combination of HO with NO

1. Reaction evaluated

HO + NO + M -> HN0

2 + M

Related reactions

HN0

2 + M -> HO + NO _+ M

HO + CO -> C0

2 + H

HO + H

2

-> H

2 0 + H

AH

298

kJ/mol kcal/mol

-209.32 (-50.03)

209.32 ( 50.03)

-103.97 (-24.85)

- 62.81 (-15.01)

(a)

Data

Results

k x 10

31

6 i i -2 " x cm molecule s

4 ± 2

2.5 ± 1

k x 10

31

6

i , -2 -1 cm molecule s

4.1 ± 0.6

1.9 ± 0.3

k^H^./k^He) - 2.3 ±

System

£(M)/torr Fast flow experiments with

5

8

T/K

300

416

0.9

excess N0

2 added to H atoms

in Ar, T = 297 K. OH detected

by resonance fluorescence

ANDERSON, KAUFMAN, 1972 (b)

Flash photolysis of N0

2 in

presence of H

2 (2.5 or 15

torr) and NO (<0.4 torr) . He

added to bring total pressure

to 30 torr. OH detected by U.V.

absorption.

MORLEY, SMITH, 1972 (c)

15
HO + NO + M

k x 10

31

6 . . -2 -1

cm molecule s

13

8.0

3.6

k (AO/k^He) = 0.45 at 298 K

T/K

273

298

398

k x 10

13

cm molecule s

0.8

1.4

2.2

5

P(M)/torr

5

10

20

82

k = 34k, + 234k.

3 4

(expression derived from data)

value reported:

-12

k = 6 x 10

cm molecule s

Flow experiment with

OH (from H + N0

2

)

and excess NO

.

OH detected by e.s.r.

M = He (0.5 to 5 torr)

.

WESTENBERG, DeHAAS , 1972 (d)

Pulsed vacuum u.v.

photolysis of ^0 in

presence of NO and excess

He (5 - 82 torr) . OH

detected by resonance

fluorescence

STUHL, NIKI, 1972 (e)

Photolysis of N

2 0 (47 torr)

in presence of (760 torr),

0

2 (50 torr), CO (110 torr),

and NO (60 or 120 mtorr) . 3>(N0 2

)

measured. T = 300 K.

SIMONAITIS, HEICKLEN, 1973 (f)

is the pressure dependent rate constant defined by the expression:

d[HN0

2 ]/dt = k'[H0][N0]

16
tiO + NO 4- M 3

4 . Preferred values

Preferred values of k^ are given in Figure 1.

A log k = ± 0.5

Values of k based on a N efficiency of 0.5

5 . Remarks

Experimental results are in satisfactory agreement in the sense that

all the data can be fitted with a maximum deviation of ±40% (see Table 1)

.

At the present time this is probably all that can be expected. The present

fit is based on RRKM calculations (g,h) assuming a loose complex [transition

state frequencies 3600, 1600, 60(2), and 40 yielding k <* (300) = 2 x 10

_11

3 -1 -1

cm molecule s ] and with all overall rotations active. The last ignores

angular momentum conservation. The justification is that in other cases

when this is combined with the two adjustable parameters k^<» and A (collision

efficiency) a satisfactory fit can be made over large temperature ranges (h)

.

The symbol k^ denotes the limiting high pressure second order rate constant

for reaction 1. The approach is thus largely empirical. In this study \

is .8 and the collision diameter 6.5A. Third body efficiencies are He(.42),

Ar(.21), and 1^(1.0). All calculations are based on the more stable trans-Hl^

form. Values of k^ calculated for the cis form are about 20% slower.

Conversion to values of k^ can be effected through the equilibrium constant

log

1Q K

p

(atm) = 7.7516 - 10976/T (derived from thermochemical data in

ref. j.).

6. Comments on measurements

ref f . The value reported for k^[M] is based on the values

k„ = 1.35 x

10~13 and k, = 7.1 x

10~ 15 cm

3molecule

-1

s _1

(i)

.

3 4

17
HO + NO + M 4

Table 1. Comparison between Experimental and Calculated Values

° f k

l1 31 k

1 x 10

J1

6 . . -2 -1

cm molecule s Ref M P(M)/torr T/K Exptl. Calc,

(b) Ar 5 297 4 3.8

8 2.5 3.3

(c) He 30 300 4.1 4.1

416 1.9 2.4

(d) He 3 273 13 8.7

298 8 6.9

398 3.6 3.8

Ar 3 298 3.6 3.5

(e) He 5 298 5.2 6.2

10 4.4 5.5

20 3.4 4.3

82 1.9 2.9

(f) H

2 ,CO,02 ,N

20 970 300 1.9 1.5

X(H

2 )=0.78

18
03 +TS+

g.+ z O II o o

-H <4-l y

co c

<u o U -H

4J

CJ CO .C h U JJS

0)u

M-l

Co c

(0 T3

•W

G

CO CO C0 OJ u u3

01 -u

•u eg CO U U 01a. u e

0) 01 -a u u0 u-io

•o

Vi c

•H

O

•U AJU

01

C

in

•H

fa

(D3S-^nro3now/^D))i

19
HO + NO + M

References

D. D. Wagman, et al, NBS Technical Note 270-3 (Jan. 1968).

J. G. Anderson and F. Kaufman, Chem. Phys . Lett. 16, 375 (1972)

C. Morley and I. W. M. Smith, J. Chem. Soc. Far. Trans. II 68^,

1016 (1972).

A. A. Westenberg and N. DeHaas , J. Chem. Phys. 5_7, 5375 (1972).

F. Stuhl and H. Niki , J. Chem. Phys. 5_7, 3677 (1972).

R. Simonaitis and J. Heicklen, J. Phys. Chem. 7_7, 1096 (1973).

P. J. Robinson and K. A. Holbrook, "Unimolecular Reactions",

Wiley-Interscience , New York (1972).

W. Tsang, Int. J. Chem. Kinetics, to be published.

F. Stuhl and H. Niki, J. Chem. Phys. 57., 3671, 3677 (1972).

D. R. Stull and H. Prophet, JANAF Thermochemical Tables, 2d

Edition, Nat. Stand. Ref. Data Ser. , Nat. Bur. Stand. (US) 37,

June 1971.

W. Tsang

May 1973

20
Chemical Kinetics Data Survey

The Combination of HO with NO,

Reaction evaluated

HO + N0

2 + M -» HN03 + M

^298

kj/mol

-207.2

kcal/mol

(-49.52)

(a,b)

k.

Related reactions

HN0

3 + M -» HO + N02 + M

HO + HN0

3

-» H

2 0 + N03 HO + CO -» C0

2 + H

207.2

-76

-103.97

(49.52)

(-18)

(-24.85)

Data

Direct Studies

Results

k

x /k = 2.2 x 10

cm^ molecule ^

-20

-29

k

x = 1.6 x 10

6 . . -2 -1 cm molecule s

System

Nitric acid photolysis at 300 K

and 150-750 torr Kr. Measured

change in $ ^^2^ as funct-i- on °f

[Kr].

BERCES, FORGETEG, 1970 (c)

Mass spectrometric study of

H + N0

2

-» HO + NO at 0.2 to 1 torr

total pressure. Measure A [N0

2

]

MULCAHY, WILLIAMS, 1971 (d)

21
*

k' x 10

12

cm3 molecule" J-s "

1 T = 300 K

1

2.0

3.3

T = 416 K

0.4

0.75

1.6

P(M)/ torr

30

100

300

HO + N0

2 + M 2

Flash photolysis of N0

2 in presence of H

2 at 300 and

416 K, 20-300 torr He,

Followed disappearance of OH

by resonance absorption.

k

1 (SF,)/k1 (He) = 4.8 ± 0,

k

1 (H

2 )/k

1 (He) = 4 ± 1 MORLEY, SMITH, 1972 (e)

K,/k^ = 15 exp (380/T)

where k^ = limiting high

pressure 2nd order value for k-^

18 \l\ = 2 x 10

cnfV molecule

exp (550/T)

M = He

k

1 (H

2 0)/k

1 (He) ~ 8

k

1 (C0)/k

1 (He) ~ 1.5

Photolysis of N0

2 at 228.8 nm in

presence of 3-20 torr H

2 0, 0-1000 torr

He, 1-350 torr CO, and

3-30 torr N0

2 at 300 and 423 K.

Measured $ (C0

2

)

SIMONAITIS, HEICKLEN, 1972 (f)

ki x 1030

6 i-2-l cm molecule s

1 ± 0.3

0.8

0.6

2

P(Ar) /torr

0.5-3

6

10

P = 8 torr

X(N

2

) = 0.8

X(Ar) =0.2

Fast flow experiments with excess

N0

2 added to flowing H atoms in Ar

at 297K. OH detected by

resonance fluorescence.

ANDERSON, KAUFMAN, 1972 (g)

k' is the pressure dependent rate constant defined by the expression

d(HN0

3 ]/dt - k' [R0][N0

2

].

22
HO + N0

2 + M

k x x 10

30

6 . . -2 -1 cm molecule s

2.01

1.57

0.58

0.83

M

He

He

He

Ar

T/K

273

298

398

298

Similar experiments as in ref. (g)

except that OH was detected by

e.s.r. P = 0.5 to 5 torr.

WESTENBERG, DEHAAS, 1972 (h)

b. Indirect Studies

k

2 [M] = 0.16 s -1

[M] = 1 atm N

2

, T = 670 K

Decomposition of HNO^ in 1 atm

N

2 in static system. [HNO^] and

[N0

2

] determined by absorption.

JOHNSTON et al, 1953 (i)

k

2 x 10

19

cm^molecule ^"s ^

0.53

1.7

4.8

P(HN0

3

) ~ 3 torr

T/K

648

673

698

Decomposition of HNO^ in static

system. P(KNCL) was 1.5-20 tor

[N0

2

] determined by absorption.

k

2 (M) /k

2 (HN0

3

) M

1

0.25

0.15

0.1

(T = 673 K)

H

2 0

C0„

°2

Ar

JOHNSTON et al, 1955 (j)

23
k

2 = 2.6 x 10 exp (-15,400/T)

3 . i -1 -1 cm molecule s

HO + N0

2 + M

Shock tube study of HNO^

decomposition in 500 torr Ar

(2-4% HN0

3

) at 800-1200 K.

Rate determined from NO^

appearance

.

HARRISON et al, 1962 (k)

k

2 [M] = 0.012 s -1

Preferred value

Decomposition of HN0

3 at 622 K

in N

2

; P(Hi:0

3

) torr, total

pressure 680 and 230 torr. Rate

determined from A [HNO^] and agrees

with that determined from A [NOg].

GODFREY, et al, 1965 (I)

Preferred values of k^ are given in Figure 1. A log k = + 0.3

Values of k based on a N

2 efficiency of 0.26

5 . Remarks

The fit of the data is based on RRKM calculations (o,p)

a loose complex and overall rotations active. The transition state

structure is 3600, 1600(2), 760, 40(2) and 2 free internal rotors /no 11 o (1.6 x 10 g-cm ). This yields k (300 K) = 1.0 x 10 cm

molecule . The collision diameter is 6.5A and the collision

efficiency is 1. The third body efficiencies are HNO^ = 1.00, He = .26,

Ar = .12, and N

2 = .26. A summary of the data on third body effects can

be found in Table 3. A satisfactory fit can also be obtained with a

24
HO + N0

2 + M

transition-state model with an elongated central bond (factor of 3)

and with the overall rotation about this bond as active, (p)

.

Except for ref. c and d, results can be fitted to within a factor of

2. This is summarized in Tables 1 and 2. Note that the data range

from .5 torr to an atmosphere and 273-1100 K and involves the forward

and reverse reactions. The larger discrepancies of ref. c and d

(compared to the other results) can be attributed to errors in

specification of the reaction mechanism.

6. Comments on measurements

ref c

.

From the measured k^/k^, taking the value of

-13 3 -1 -1 = 1.4 x 10 cm molecule s (ref m), the value k^ =

33 6 2 1 3 x 10 cm molecule s is derived. Note that in nitric acid

systems at low temperatures, reactions are often subject to surface

effects

.

ref. d. This is basically a qualitative study with respect

to the process of interest.

ref. f. The value of k^ used in the present analysis to get

-13 3 -1 -1

the values of k^ in Table 1 is 1.33 x 10 cm molecule s (n)

.

ref. i and i. This fit does not substantiate the claims that

the measured rates are in the limiting high pressure region. The

present results indicate that k2[M]/k2°°~ 0.1.

25
HO + N0

2 + M

Table 1 Comparison between Experimental and Calculated Values of k

1

Ref

(h)

M

He

Ar

P(M)/torr

3

3

3

3

T/K

273

298

398

298

h x 1031

cm^molecule~^s~'1"

Exptl ,

20

16

6

8

Calc

,

22

18

11

10

(e) He

He

30

100

300

30

100

300

300

416

10.4

6.2

3.5

5.8

3.3

2.2

8.6

5.3

2.9

6.1

4.3

2.7

(f) He

He

30

100

300

1000

30

100

300

1000

300

423

13.6

9.5

5.2

1.9

8.6

6.7

4.1

1.8

8.6

5.3

2.9

1.4

5.8

4.1

2.6

1.5

26
k l x 10

31

6

:—: -2 -l cm molecule s Ref

.

M P(M)/torr T/K Exptl Calc.

(g) Ar .5-3 297 10 12

6 8 8

10 6 7.5

N

2 ,Ar 8 297 20 19

(c) Kr 300 300 .03 2

(d) Ar 1 300 170 10

27
HO + N0

2 + M 8

Table 2 Comparison between Experimental and Calculated Values for

k

2 x 10

19

cm molecule s Ref M P(M)/torr T/K Exptl

.

Calc

(k) Ar 500 900 980 800

1UUU DUUU yuuu

1100 25000 50000

(j) HN0„

3 3 648 .53 .63

673 1.7 2.3

698 4.8 8.0

(£) N

2 760 622 .012 .01^

(i) N

2 760 670 .15 .22

28
HO + N0

2 + M

Table 3. Summary of Experimental Data on Third Body Effects

M

HNO,

He

Ar

H

2 0

SF^

CO,

H

2

°2

CO

Ref. j

1

- 0.1

- 1

- 0. 25

Ref . e Ref . f Ref. h Ref. g

1

0.5

4.8

4.0

0.15

2.2

1.5

29
+T+

CM §~CM + Z 8 " c u 0 o

•H 14-1 4J ^—

o

CO

C

o> o U -H

4-1 01 CO u u c

CO XI

4J

C

oi eg cO 41 0 U3

CD 4J 4J CO CO U u <ua U £

01 Ot 13 4-1 U0 <Mo

•au c

•h o

4-1 4-1 o

01 c

EH 4-1

60

•rl

55 8

(D3S-^STinD3iaJ/J0)X

30
HO + N0

2 + M 10

References

a. D. D. Wagman, et al, NBS Technical Note 270-3 (Jan. 1968).

b. D. R. Stull and H. Prophet, "JANAF Thermochemical Tables,

2d Ed," Nat. Stand. Ref. Data Ser. Nat. Bur. Stand. (U. S.),

3_7 (June 1971) .

c. T. Berces and S. Forgeteg, Trans. Faraday Soc. 66_, 640 (1970).

d. M. F. R. Mulcahy and R. H. Williams, J. Chem. Phys. 54, 5215

(1971).

e. C. Morley and I. W. M. Smith J. Chem. Soc, Far. Trans. II,

68 1016 (1972).

f. R. Simonaitis and J. Heieklen, int. J. Chem. Kinetics 4, 529 (1972).

g. J. G. Anderson and F. Kaufman, Chem. Phys. Lett. 1_6, 3 75 (1972).

h. A. A. Westenberg and N . deHaas, J. Chem. Phys. 57, 5375 (1972).

i. H. S. Johnston, L. Foering, and R. J. Thompson, J. Phys. Chem.

57, 390 (1953).

j. H. S. Johnston, L. Foering and J. R. White, J. Am. Chem. Soc.

1J_, 42U8 (1955).

k. H. Harrison, H. S. Johnston and E. R. Hardwicke, J. Am. Chem.

Soc. 84, 2478 (1962) .

i. T. S. Godfrey, E. D. Hughes and C. Ingold, J. Chem. Soc.

1063 (1965).

31
HO + N0

2 + M

m. R. F. Hampson et al, "Survey of Photochemical and Rate Data

for Twenty-Eight Reactions of Interest in Atmospheric

Chemistry", to be published J. Phys. Chem. Ref. Data 2,

No. 2 (1973).

n. A. A. Westenberg and N. deHaas, J. Chem. Phys. 58, 4061 (1973).

o. P. J. Robinson and K. A. Holbrook, Unimolecular Reactions,

Wi ley-Interscience, New York (1972).

p. W. Tsang, Int. J. Chem. Kinetics, to be published.

W. Tsang

May, 1973

32
Chemical Kinetics Data Survey

Photochemistry of NO

Primary Photochemical Transitions

a . Dissociation

Reaction kj/mol kcal /mol \ threshold (nm)

NO -» N(

4

S) + 0(

3 P) 627.9 (150.07) 190.5

-* N(

4

S) + 0(

XD) 817.7 (195.43) 146.3

-» N(

4

S) + 0(

1 S) 1032.1 (246.68) 115.9

-> N(

2D) + 0(

3 P) 857.8 (205.03) 139.5

-» N(

2 D) + 0(

1 D) 1047.6 (250.38) 114.2

-> N(

2 D) + 0(

1 S) 1262.1 (301.64) 94.8

AHq values calculated from ZXH° (0) in (a) and energies of excitation

of 0(

1 D), 0(

1 S), and N(

2D) in (b)

.

The bond dissociation energy has been determined to be 52400 ±

10 cm"

1 or 626.84 ± 0.12 kj/mol (149.82 ± 0.03 kcal/mol) (c) . This

energy corresponds to a threshold wavelength of 190.8 nm.

b . Electronic Energy Levels of NO and Transitions

State To/cm"

1 X(vac) /nm Transitions

D(

2

S

+

) 53291 (a) 187.65 d-»x (e)

c(

2n> 52372 (a) 190.94 0 -» .X ( 6)

B(

2n

r

) 45505 (a) 219.76 B -» X (£5) A(V) 44199.2 (a) 226.25 A^X (v)

a(

4n) 37965 ± 25 (b) 263

x(\/2) 0

a . From ref. (x)

b. From ref. (y)

33
2

2 . Absorption Coefficient Data

The spectroscopy of NO absorption bands has been studied in

detail. It is summarized in reference (x) . See also references

(f, z) for examples of the complexities that occur.

Hudson (h) in 1971 reviewed the u.v. absorption coefficient

measurements on NO, with emphasis on data for X < 160 nm. Marmo

(d) and Thompson, Harteck and Reeves (e) reported absorption

coefficients covering the range 110 < X < 230 nm. These coefficients

are not independent of the resolution of their instruments except

possibly for X < 130 nm. See Figures 1 and 2 for a qualitative

view of the spectrum.

a. X < 130 nm Watanabe, Matsuga and Sakai, 1967, (g) presented extensive tables of absorption coefficients and photoionization

yields . For the range 106 < X < 135 nm these are based on measurements in a 10 cm long cell with 0.02 nm band pass. There is

reasonable agreement with (d)

.

b. Banded absorption Integrated absorption coefficients

and oscillator strengths have been measured for the (3, v, 6 and

e band systems. These are summarized below as oscillator strengths,

f (v', v") for individual bands, v' is the vibrational quantum number

in the upper state, v" is that in the ground state. This oscillator

strength is related to the integrated absorption coefficient for

the same band via

f(v', v") = (mc

2 /n e2N

0 ) (K0 /F(v"))

= 4.203 x 10" 8 (K

Q /F(v"))

34
where c is the velocity of light, m and e are the mass and charge

3 of the electron, N

Q

is the number of molecules per cm at 1 atm.

and 273.15 K, and F(v") is the fraction of these molecules in the

lower vibrational state (under the conditions of the experiment).

. . -2 -1

KQ is m cm atm

Methods of measurement. Bethke 1959 (aa), measured integrated

absorption coefficients photometrically for NO pressurized with

argon. Callear and Pilling, 1970 (bb), used a similar spectrographic

studies and analysis of fluorescence intensities. Farmer et al,

1972 (cc) and Pery-Thorne and Banfield, 1970 (dd) measured refractive

index dispersion near absorption lines. Marr, 1964 (ee), reanalyzed

the earlier data and presented smoothed values for many transitions

in the v and P bands.

Oscillator Strengths

Q bands (B-X), ref(aa) *

v', v" 10

4

f(v' v

M

) v', v" 10

4

f(v', v")

2, 0 0.0155 ± 107 9, 0 3.58 ± 10%

3, 0 0.0461 ± 107 11, 0 3.62 ± 207

4, 0 0.138 ± 207o 12, 0 23 . 1 ± 107

5, 0 0.264 ± 107 14, 0 2.006 ± 107

6, 0 0.462 ± 207

35
4

v bands (A-X)

v\ v" Kff(v', v")

Ref (aa) Ref (cc) * Ref (dd)

0, 0 3.99 ± 10% 4.0 ± 5% 3.64 ± 0.05

1, 0 7.88 ± 10% 8.09 ± 5%

2, 0 6.73 ± 107„ 7.00 + 5%

3, 0 3.60 ± 10% 2.4 ± 25%

bands (C-X)

v

1 , v" 10

4 f(v% v")

Ref (aa) Ref (bb) *

0. 0 24.9 ± 10% 56 ± 18%

1, 0 57.8 ± 10%

2, 0 27.4 ± 10%

£ bands (D-X)

10

4

f(v', v")

Ref (aa) * Re f (bb)

0, 0 25.4 ± 10% same as for (aa)

1, 0 46.0 ± 10%

2, 0 33.2 ± 10%

* Preferred values

36
5

3 . Photochemical data

There have been two recent reviews of the photochemistry of NO:

1) Heicklen and Cohen, 1968, (ref. i), and 2) Preston and Cvetanovic,

1972, (ref j).

a. X > 191 nm

Table I summarizes the results of studies of the photochemistry

of NO at photon energies less than the dissociation energy.

Absorption produces an excited NO. Products are formed

exclusively from reactions of this excited molecular species.

MECHANISM :

NO + hv * NO*

NO + NO + hv

NO +N0 * 2 NO

NO*+NO > N

2 + 02 NO*+NO > N

2 0 + 0

2N0 + 0

2

-* 2N0

2

b. X < 191 nm

Table II summarizes the results of studies of the photochemistry

of NO at photon energies greater than the dissociation energy. $(N

2

) is

always < 1, indicating that absorption produces bound excited states

which can fluoresce or be collisionally quenched or dissociate. Products

are formed by atom-molecule reactions.

37
MECHANISM:

NO + hv -> NO

NO" -» NO + hv

NO" + M -* NO + M

NO" + m-»n + o+ m

N + NO -> N

2 + 0

0 4- NO + M -> N0 o + M

Table I . Summary of data on photochemistry of NO at energies less

than the dissociation energy (i.e. at X > 191 nm)

.

X (nm)P(NO)

(torr) Products

Quantum

Yields

Excited

State

214,

226

(Cd(II))

HEICKLEN, ]

20-600

.966 (k)

N

2

, N0

2 N

2 0

$(N )=0.19

$(N

2 0)=0.096

0(-N0) (calc)

- 1.05 (1 >

v - 1 and

v = 0 of

A

2

Z

199,

193,

186

(Al spark)

Absorpt

MacDONALD

,

50-650

ion of 186

1928 (£)

N,, N0

2

,

N

2 0

nm line proba

$(-N0) =

1.45 (2)

Dly not importa

probably

v = 5 of

B

2 n by

X=199 nm.

at.

Note 1 . Obtained indirectly; based on mechanism assuming $(N0 0) = 2

in presence of large cone, of CH

Note 2 . Obtained directly; incident light intensity measured by

irradiation of thermocouple.
7

Table II. Summary of data on photochemistry of NO at energies

greater than the dissociation energy (i.e. at A < 191 nm)

.

A (nm)

P(NO)

(torr) Products

Quantum

.

Yields U;

Excited

State

VL60

(H discharge)

2-500 N2> N0

2 $(N

2

)=.2-.4

<D(N0

2

) = .3-.7

$(-N0) =

0.8-1.8

2 2 A S, B n

2 2 C% D S

147 10-700 N_, N0

2 «

2 o

(2>

$(N )=. 3-.

5

$(N0

2 )=. 6-1.1

*(N

2O)=.02-.l

$(-N0) =

1.3-2.7

17 = 7 of

D

2

Z

v = 3 of

E

2

Z

123.6,

116.5

LEIGA, TA

10-950

fLOR, 1965

N

2

, N0

2

(m)

$(N

2 )=.2-.5

*(N0

2 )=. 4-1.0

$(-N0) =

1.0-2.3

„«+ (3) NO '

VL83.2

(Hg arc)

and metal

spark

sources

FLORY, JO]

0.07-7

.-INSTON, 193

N

2 , N0

2

5 (n)

only dcmp

.

rate of

NO meas

.

v = 1 of

C

2

II with

perhaps some

abs . to v = 9

of B

2 n

Note 1 . $ values in ref (I) based on $(0^) = 2 in photolysis of 1 atm.

0 flowing through reaction vessel.

Note 2 . Secondary product from N + N0

2 (see ref. o)

.

Note 3. Ionization potential of NO = 9.25 eV (corresponds to A = 134 nm;

at 123.6 nm the ionization yield is 0.77 (g)

.

39
In addition to these studies giving values of quantum yields

of product formation, the wavelength dependence of the formation of

oxygen atoms from photolysis of NO has been studied by Stuhl and Niki

(u) . They detected 0 atoms (by WO emission) when NO was photolyzed

at \ > 160 nm and at ^ > 180 nm but not at X > 210 nm. These

observations are consistent with the value of the thermochemical

threshold for photodissociation (191 nm)

.

4 . Excited States of NO

a . Lifetimes

(1) Mean lifetimes (1/e) of low-lying excited states of

NO with respect to spontaneous radiation and predissociation

.

State

A

2

1

B

2 n

c

2 n

D

2

E

Note (a)

Lifetime fry s

2 x 10

3 x 10

6

6 x

10~ 10

(a)

2 x 10

predissociation at limiting high [Ar]

Reference

(P)

(q)

(c)

(r)

40
(2) Specific rate constants for spontaneous radiation

and predissociation (all paths) . From reference (c)

.

Rate constant , k/s

emission emission

State to X

2

II to A

2

I predissociation

A

2 Z 0.51 x 10

7

C

2 n 5.1 x 10

7 3.5 x 10

7 1.65 x 10

9 (a)

D

2

Z 4.1 x 10

7 0.95 x 10

7 <0.8 x 10

7

Note (a) : k (predissociation) at limiting high [Ar]

.

b . Quenching of excited states

The table below gives ratios of total quenching coefficients,

3 -1 -1

k , in cm molecule s , to total spontaneous decay rates, i.e.

predissociation plus radiative transitions, (or k^ + £k^) , in

reciprocal seconds. These are based on the quenching half pressure,

i.e. that pressure of added gas which reduces the intensity of

fluorescence to one-half its value in the absence of added gas.

Data from reference (c) and at 298 K except as indicated.

The following formula relates the quenching coefficient, k^ in

3 -1 -1 cm molecule s , the radiative lifetime, T in s, and the half ' ' o t v -2

pressure, Pq in kN m

1 ft Y

T o= 4a X 10 /P 0.5

41
10 ^ k^ * t /cm^ molecule ^ Q o

State NO N, Ar CO,

A(

2 E)

c(

2 s)

D(

2 ^)

47

2.34

71

0164

0.91

5.6

< 0.016

< 0.008

3.08

79

2.0

22.8

34 (a)

State N

2 0 H

2 0 CO,

B( H) 140 (b,c) 60 (b,c) < 1500 (b,c) 30 (b,c)

(a) Reference (s), data on 0^

(b) Reference (t)

(c) T = 196 K

(Use values of in section 4a to obtain from the table)

5 . Preferred values

a. Absorption coefficients

i) Banded spectra (data in section 2b)

{3 bands. Use data from (aa)

Y bands. Use data from (cc)

5 bands. Use data from (bb) See remarks

e bands. Use data from (aa)

ii) X < 130 ran. Use data from (g)

42
11

b . Quantum yields

No general recommendations. Product yields depend upon

the composition of the mixture being photolyzed and the wavelength

of the exciting light. See remarks for some estimates pertinent

to absorption in the atmosphere.

6 . Remarks

a . Absorption coefficients

(i) X > 130 nm . The spectrum is highly structured. The

apparent absorption coefficients that have been measured depend

strongly upon instrumental resolution. Figure 1 may be used only

to locate the wavelengths where absorption occurs but not to obtain

the magnitude of the absorption coefficient.

Values for absorption coefficients, either for bands or lines,

should be developed from oscillator strengths? f(v', v"), populations

of absorbers and line strength formulae. See (w) for application

of the technique to NO.

The oscillator strength for 5 (0,0) measured by Callear and Piling

(bb) is preferred to Bethke's (aa) because it is based on two methodsintegrated absorption and fluorescence lifetimes-that agree. This

agreement is an argument that large systematic biases are absent

from the spectrographic measurements. The value from (bb) is 2.25 times

that from (aa)

.

43
12

Oscillator strengths for 6 (1,0 and 6 (2,0) are available only

from (aa) . Should they be used as is, or increased, i.e., normalized

to the 6 (0,0) reported in (bb)? Two arguments suggest that they

should be increased. First, the reported oscillator strengths

it vary approximately as do the Franck-Condon factors. Secondly,

Callear and Pilling show that collisional (pressure) broadening is

much weaker for the 5 (0,0) than the e (0,0) band. This suggests

that the 6 bands were insufficiently broadened in Bethke's experiments.

The argument is weak because of the high pressures (100 psia) of

argon used by Bethke.

Arbitrarily we suggest that the 6 (1,0) and 6 (2,0) oscillator

strengths from (aa) given in section 2b should be multiplied by 2.25.

When these new values are used in aeronomic calculations they should

be considered to be upper limits.

(ii) \ < 130 nm . Absorption into a continuum is the most

important element here. The higher resolution study (g) has been

selected. The data in Figure 2 are in reasonable agreement.

44
13

6 .b . Quantum Yields

Product formation following absorption of light by NO.

A* 2 ~\~ 2-pr 2 2 *f* Bound excited states of NO, a I!, A I , B C H and D Z are formed

in the photon absorption by NO in the wavelength range 230 > X

-> 150 nm.

Other observed products are due to reactions of NO \ Pertinent

processes are reaction of NO" with NO, predissociation (atom formation),

reactive quenching and physical quenching. The first is important

in laboratory studies but need not be considered for the photolysis

of trace amounts of NO in air. (Mechanisms applicable to laboratory

photolyses are given in Section 3 a.b.)

The other processes are important for atmospheric photolysis of

NO. Cieslik and Nicolet (w) have developed an overall photodissociation

rate. The remarks that follow rely heavily on their discussion and

on two recent reviews (i, j) and the summary in (c)

.

Each state is considered separately. An estimate is made for an

"effective initial quantum yield" of products (e.g. 0, N, NO^)

.

More precisely, these estimates are ratios: Products formed per NO

disappearing by all paths. For each excited electronic state a

vibrational-rotational level is reached that is strongly predissociated

.

(The evidence is either absence of higher levels in emission spectra

or line broadening) . All higher levels are assumed to dissociate to

atoms either directly or via another electronic state. The main

discussion is about the fate of lower levels.

45
NO (A

2E

+

)

This is the upper state for the v bands (X -» A) . Vibrational

levels v' > 4 are predissociated . 0(0) = 0(N) = 1, v' > 4. For

lower levels the only important atmospheric reaction partner is

O^Cs). (N2 is 2000 fold less efficient and is ignored here).

Quenching by 0^ may be a chemical reaction, in analogy to NO and

(s, k, v) . The level A(v = 0) is 1.017 ev below the dissociation

limit for the ground state (forming ground state atoms)

The minimum required steps are

NO + hv -» N0(A

2 E

+

, v = 0) 1

N0(A

2 E+

)

-+ NO + hv 2

N0(A

2 Z+

) + 0

2 NO + 0

2 3

-» N0

2 + 0 4

0(0) = 0(NO

2

) ~ k

4

[0

2 ]/((k

3 + k4 )[0

2

] + k

2

)

Reaction (4) is speculative. It has not been observed. 0 can

vary from zero to near 1 depending upon the value of k, /k^. We

guess that k^/k^ > 1 .

Rate constants are = 5 x 10 s ^ (c) and (k^ + k^) = 1.6 x 10

^

3 -1-1

cm molecule s (s). At 20 km radiative loss would be about 870

of the total but would increase in importance with increasing altitude

46
This is the upper state for the (3 bands (X -> B) . Emission has

not been observed for v' > 7 (which lies close to the dissociation

limit of NO) , 0(0) = 0(N) = 1, v' > 7. Our knowledge of the photochemistry of this state is sketchy. We follow Preston and Cvetanovic

2 +

(j) and suggest a behavior similar to that of A £ .

This is the upper state of the 6 bands (X -» C) . Emission from

v' > 0 has not been observed. 0(0) = 0(N) = 1, v' > 0. Emission

has been observed from v' = 0, but even here some levels are

predissociated . This state has its minimum energy at approximately

the dissociation limit for the X state. Cieslik and Nicolet ( w )

consider the C state to be the most important contributor to the

photodissociation process in the upper atmosphere.

A mechanism for photolysis in air that can be used to estimate

a lower limit for the quantum yield is

2 NO + hv N0(C Tl, v = 0)

NO (C

2n) -» NO + hv (to X2n and A2S

+

)

N0(C2

TI) -» N + 0

N0(C

2

TT) + M -» loss of N0(C

2

TI) 4

3

2

1

47
0(N) = 0(0) > k

3 /(k

3 + k

2 + k

4

[M])

Q Q 7 - 1 0

> 17 x 10/(17 x 10° + 9 x 10' + 15 x 10 [M])

> 1/(1 + 0.8 x 10 [M])

Rate constants given in reference [c] have been used. These apply

2 to N0(C II, v = 0) the level least likely to predissociate . The

value for k^ is for nitrogen. It is used here as an upper limit

for physical quenching.

18 -3

At 20 km, [M] ~ 2 x 10 molecules cm and 0 > 0.4. This lower

limit will increase with altitude. Reactive quenching by 0^ (see

2 +

remarks on N0(A T, )) would also increase 0(0) .

This is the upperstate of the e bands (X -* D) . It has approximately

2 +

the same energy as C T, . However, the rate of predissociation is

less than 1/5 that of spontaneous emission:

N0(D

2 S+

)

NO + hv -» N0(D

2S

+

)

1

N0(D

2 Z

+

)

-> NO + hv (to X and A)) 2

N0(D

2 Z+

)

-» N + 0 3

4

5

48
Ignoring reaction 5

0(0) = 0(N) = k

3 /(k

3 + k

2 + k4

[N

2

])

= (< 8 x 10

6 )/((< 8 x 106

) + 5 x 10

7 + 3 x 10" 10

[N

2

1)

< 1/(1 + 60 + 3.8 x 10" 17

[N

2

])

Thus radiative loss and quenching are controlling. If, however,

reaction 5 is efficient and is a chemical reaction, the quantum

2 +

yields would be larger. See discussion of N0(A E ).

N0(a4

TT)

Unimportant. Gas phase absorption to this state is not observed.

Excitation to this state probably is followed only by quenching to

the ground state.

49
18

Summary of estimates of quantum yields for photolysis of traces of NO

in air

lectronic State Vibrational level Reactions Products /ANO'

formed Products

N0(A

2 E+

) v>4 N+0 ~ 1 v = 0 N0

2 +0? 0-1

reactive quenching

N0(B

2n) v>7 N+0 ~ 1 v < 7 ? possibly

similar to A'

N0(C

2

TT) v > 0 N+0 ~ 1 v = 0 N+0 pressure dependent, > 0.4 at 20 km.

~ 0, radiative loss

and quenching dominate

NO(a^IT) - - Unimportant

6.b. Photodissociation of NO in the stratosphere

The discussion of the photochemistry of NO given in earlier

sections is not sufficient to define the stratospheric photodissociation

of NO. A major fraction of the photodissociation occurs in the same

wavelength region as that for the Schumann-Runge absorption bands

of 0

2

.

A line by line analysis must be made to determine the overlap

between the radiation transmitted through the S-R bands and the NO

absorption lines. From this analysis the effective absorption by

NO can be obtained. Only then can the photochemical discussion be

applied. See Cieslik and Nicolet (w) for a detailed study of the

problem

.

50

N0(D

2S+

)
19

i—J—i—i—i—

r

12 II 10 9 8 7

^20^

o

to<

s

j ill

ABSORPTION OF NO

La.

1 r

1500 1700 1900

WAVELENGTH A (x)

2100 2300

Fig. 1 Apparent absorption coefficient of NO in the wavelength region

150 - 230 nm in units of cm"

1 (atm at 273 K)

_1

base e. The

positions of the band heads for the 6, 3, e, and v bands are

indicated at the top. Band pass: 0.085 nm. Data of F.

Marmo. From Watanabe, Zelikoff, Inn, Geophysical Research

Paper No. 21, AFCRL, June 1953.

51
2U

I 100 H200~ 1300 1400 1500 1600

WAVELENGTH, (A)

Fig. 2 Apparent absorption coefficient of NO in the wavelength region

110 - 160 nm in units of cm ^ (atm at 273 K) ^ base e.

Data of F. Marmo. From Watanabe, Zelikoff, Inn, Geophysical

Research Paoer No 21. AFCRL. June 1Q5V

52
21

References

a. D. D. Wagman et al, NBS Technical Note 270-3 (Jan. 1968).

b. C. E. Moore, NBS Circular 467, vol. 1 (1949).

c. A. B. Callear and M. J. Pilling, Trans. Far. Soc. 66_, 1618 (1970).

d. F. F. Marmo, J. Opt. Soc. Am. _43, 1186 (1953).

e. B. A. Thompson, P. Harteck, and R. R. Reeves, Jr., J. Geophys

.

Res. 68, 6431 (1963)

.

f. K. Dressier and E. Miescher, Astrophys. J. 141 , 1266 (1965).

g. K. Watanabe, F. M. Matsunaga, and H. Sakai, Appl. Optics 6_, 391

(1967) .

h. R. D. Hudson, Rev. Geophys. Space Phys . 9_> 305 (1971).

i. J. Heicklen and N. Cohen, Advances in Photochemistry 5_, 157 (1968).

j. K. F. Preston and R. J. Cvetanovic, "Decomposition of Inorganic

Oxides and Sulfides", in "Comprehensive Chemical Kinetics",

ed. C. H. Bamford and C. F. H. Tipper (Elsevier Publishing Co. 1972)

vol. 4 pages 47-141.

k. J. Heicklen, J. Phys. Chem. 70, 2456 (1966).

1. J. Y. MacDonald, J. Chem. Soc. 1928 , 1 (1928).

m. A. G. Leiga and H. A. Taylor, J. Chem. Phys. 42_, 2107 (1965).

n. P. J. Flory and H. L. Johnston, J. Am. Chem. Soc. 5_7, 2461 (1935).

o. D. S. Sethi and H. A. Taylor, J. Chem. Phys. 48, 533 (1968).

p. H. Bubert and F. W. Froben, Chem. Phys. Lett. _8, 242 (1971).

q. M. Jeunehomme and A. B. F. Duncan, J. Chem. Phys. 41, 1692 (1964).

r. J. E. Hesser, J. Chem. Phys. 48. 2518 (1968).

53
22

s. L. A. Melton and W. Klemperer, Planet, Space Sci . 2_0, 157 (1972).

t. I. M. Campbell and B. A. Thrush, J. Quant. Spectrosc. Radiat.

Transfer 8, 1571 (1968)

.

u. F. Stuhl and H. Niki, Chem. Phys. Lett. 7, 197 (1970).

v. N. Cohen and J. Heicklen, J. Phys. Chem. 71, 558 (1967).

w. S. Cieslik and M. Nicolet, Planet. Space Sci. 2_1, 925 (1973).

x. E. Miescher and F. Akermann, in "Spectroscopic Data relative to

Diatomic Molecules", B. Rosen, editor. International Tables of

Selected Constants (Pergamon Press, 1970), vol 17, p. 277.

y. H. P. Broida and M. Peyron, J. Chem. Phys. 32, 1068 (1960).

z. Ch. Jungen and E. Miescher, Can. J. Phys., 46 987 (1968).

aa. G. W. Bethke, J. Chem. Phys. 3_1, 662 (1959).

bb. A. B. Callear and M. J. Pilling, Trans. Faraday Soc. 66, 1886 (1970).

cc. A. J. D. Farmer, V. Hasson and R. W. Nicholls, J. Quant.

Spectrosc. Radiat. Transfer 12, 627 (1972).

dd . A. Pery-Thorne and F. Banfield, J. Phys. B., Atom. Molec. Phys.

3, 1011 (1970).

ee. G. V. Marr, Proc. Phys. Soc, 83, 293 (1964).

H. Okabe

D. Garvin

R. Hampson

July, 1973

54
Chemical Kinetics Data Survey

The Combination Reaction of NO and 0

1. NO + 0 ( 3P) + M -» N0

2 + M k

1

2. AH° = -306.2 kj mol' 1 (-73.2 kcal mol" 1

) (a)

3 . Data

a. The rate measurements on this reaction prior to July

1970 were compiled and reviewed by Baulch, Drysdale, and

Home (b) . The major investigations of the temperature

dependence of the reaction were performed using discharge

flow systems by Clyne and Thrush (c) over the range

212-293 K, and by Klein and Herron (d) over the range

300-505 K. The third body effect was studied extensively

by Kaufman and Kelso (e) at room temperature also using

a discharge flow system.

b . Recent measurements

k, (crrwnolecule ^)

1 M T System

-3 2 6.65 x 10 He 300 K Pulsed vacuum-uv photolysis

of NO (1-3.5 torr) or of

15 x 10"J NO 300 K 0

2 (0.1 terr) in presence of

NO (< 0.3 torr) and He

(< 31 torr). 0 atom decay

rate monitored by chemi luminescent

reaction 0 + NO -» NO + hv

STUHL, NIKE 1971 (f)

55
NO + 0 + M 2

6 -2 -

1

k^(cm molecule s ) M T System

-32

13.5 x 10 Ar 300 K Pulsed photolysis of Q> 2 (0.1 torr) at 147 nm in

presence of NO (1-8 mtorr)

and Ar (6 or 10 torr). 0

atom decay rate detected by resonance fluorescence.

SLANGER, BLACK 1970 (g)

-32

6.0 x 10 Ar 296 Pulsed photolysis of 0^

22 (0.1 torr) at 147 nm. in

13.0 x 10 Ar 241 the presence of 0.1 torr

NO and 10 torr Ar. Experiments

primarily performed to measure rate constant for

0 + N0

2

-» NO + 0

2

. SLANGER, WOOD, BLACK

1973 (h)

Preferred values

k = 2.9 x 10" exp(940/T) cm molecule" s , M = 0

2 Temperature range: 200-500 K.

Estimated error limit: ± 20% at 298 K, ± 50% at other temperatures.

k(298 K) = 6.8 x 10"32 cm

6 molecule" 2

s _1

M = 0^

k(220 K) = 2.1 x 10'31cm

6 molecule"

2 s"

1 M = 0

2 Relative efficiencies for M:

N

2 (1.4); 02 (1); Ar (1)

56
NO + 0 + M 3

5 . Remarks

The recommended rate expression is that given by Baulch

et al (b). The relative efficiency values are also from

(b). This expression for k (T) has been confirmed by the

recent measurements of Stuhl and Niki at 300 K (f) and those

of Slanger, Wood, and Black at room temperature and at 241 K

(h). The earlier measurement by Slanger and Black (g) is

apparently a factor of two high. The authors speculated

that a fast secondary reaction between atomic oxygen and

vibrationally excited nitrogen dioxide produced in reaction

(1) was the cause of the higher measured rate constant.

References

(a) D. D. Wagman, W. H. Evans, V. B. Parker, I. Halow, S. M.

Bailey, and R. H. Schumn, NBS Technical Note 270-3, (1968).

(b) D. L. Baulch, D. D. Drysdale, and D. G. Home, "High Temperature Reaction Rate Data", Report No. 5 (1970), Dept. of

Physical Chemistry, The University, Leeds, England.

(c) M. A. A. Clyne and B. A. Thrush, Disc. Faraday Soc. 33_, 139

(1962) .

(d) F. S. Klein and J. T. Herron, J. Chem. Phys . 41, 1285 (1964).

(e) F. Kaufman and J. R. Kelso, Symp. Chemi luminescence, Durham,

N. C. (1965).

57
NO + 0 4- M 4

(f) F . Stuhl and H. Niki, J. Chem. Phys . 55, 3943 (1971).

(g) T. G. Slanger and G. Black, J. Chem. Phys. 53_, 3717

(1970)

.

(h) T. G. Slanger, B. J. Wood, and G. Black, Inter. J.

Chem. Kinetics 5, 615 (1973).

R. E. Huie, J. T. Herron

January, 1973

58
PHOTOCHEMISTRY OF NO

Primary Photochemical Transitions

o Reaction AH 0 X threshold (rim)

N0

2

2 3 ^ N0(X rr) + 0( P)

kj/mol

300

(kcal/mol)

(71.8) 398

NO2 -» N0(X

2

tt) + 0( D) 490 (117.2) 244

N0

2

-» N0(X

2

tt) + 0(

1S) 705 (168.4) 170

N0

2 4 3 -

-» N( S) + 0

2 (X Z

g

) 435 (103 . 9) 275

N0

2

A 1 "» NCS) + 0

2 (a

XA

g

) 529 (126.5) 226

N0

2

-> n(

4

s) + o

2 (bhp 592 (141.4) 202

N0

2

-» NOCA

2!"*") + 0(

3 P) 829 (198.2) 144

N0

2

-» N0(A

2E

+

) + 0(

1D) 1019 (243.6) 117

N0

2

-» N0(aV") + 0(

1 S) 1234 (294.8) 97

AHq values calculated using AHf°) values in (a), excitation energies

of 0( D) and 0( S) in (b), and excitation energies of N0(A2

E"'"),

0

2 (a\), and O^b 1!!*) in (c) .

59
N0

2 + hv

2 . Data

2a . Absorption Coefficient

240-500 nm See Figure I.

HALL, BLACET, 1952 (d)

400-700 nm DIXON, 1940 (e)

108-270 nm See Figures 2a, 2b, 2c, 2d

NAKAYAMA, KITAMURA,

WATANABE, 1959 (f)

405-515 nm WILKERSON, ERC0LI,

TOMPKINS, 1973 (y)

See Appendix for conversion factors for units of absorption

coefficients

.

2b. Overall Quantum yield for 0^ production, § (O2)

:

N0

2 + hv -» NO + 0 ( 3

P)

0 + N0

2

-» 0

2 + NO

X(nm) *(0

2

)'

f

$(0

2

) measured. Equal to

313 0.97 0(0) at low pressures. P(N0

2

)

366 0.92 = 10 torr. Values also given at

380 0.82 344, 406, 496, and 566 K for \

405 0.36 = 405 nm. Non-zero value at 436 nm

436 0.005 believed due to trace component

of 405 nm.

"at T = 296 K PITTS, SHARP, CHAN, 1964 (h)

60
N0

2 + h v 3

XCnm) §(0

2

)

270 1.0 Weighted average of results of

313 0.97 four studies (1928-53).

366 0.92

405 0.36

436 0.00 LEIGHTON, 1961 (i)

X(nm) $(0

2

)

313 0.99 Reassessment of data considered

366 0.96 in (i) and those reported in

380 0.82 (h).

405 0.36

436 <0.005 DEMERJIAN, KERR, CALVERT,

1974 (u)

2c. Overall quantum yield for NO production, $(N0):

X(nm) $(N0)

295-398 2.0 Relative overall quantum yield

400 1.35 for production of NO, $ (NO)

,

405 0.64 measured. Values normalized

410 0.32 to values at 313 and 366 nm in

415 0.10 (i). P(N0

2

) = 3 torr.

420 0.07 Also, see Figure 3

425 0.06 NOTE : Preliminary data

435 0.05

490 0.03

580 0.02 JONES, BAYES 1972 (g)

61
NO., + hv 4

2

3 . Preferred values

a . Absorption coefficients

240-500 nm Use data in ref (d) . See Fig. 1. (See also special note under remarks)

108-270 nm Use data in ref (f) . See Figures

2a, 2b, 2c, and 2d.

NOTE : Units of absorption coefficients

In Fig. 1, k is in units of (mm Hg at 298 K) ^cm ^ (base 10)

In Fig. 2a-d, k is in units of (atm at 273 K) ''"cm ^ (base e)

See Appendix for table of conversion factors for units.

Absorption cross--sections averaged over 10 nm intervals:

X.(nm) CT(N0

2

) X (nm) CT(N0

2

)

290 0.99 x in" 19 2 10 cm 400 6.53 x 10

300 1.41 410 6.38

310 2.18 420 6.23

320 2.98 430 5.88

330 3.74 440 5.54

340 4.54 450 5.20

350 5.20 460 4.47

360 5.69 470 4.05

370 6.04 480 3.51

380 6.23 490 3.06

390 6.38 500 2.64

a = (l/n<£) log (I /I) where n is the concentration of NO

in molecules cm and I is the path length in cm.

62
N0„ + hv

b . Primary quantum yields for 0 atom formation, 0(O( jO)

X (nm) 0(O(

3 P))

r\ c o f\ 295-398 1.0

400 o ,/u

405 r\ 0 Q

410

415 0 .05

420 0.02

425 0.01

435 0.002

440 0.001

>440 ZERO

4 . Remarks

a . Absorption coefficient

Ref. (d) Figure 1 also includes absorption coefficient data

for N„0. . Resolution in spectrum that data are based on was 0.4 nm.

2 4

It is not possible to assess the reproducibility of these absorption

coefficients. Values for N0„ and N_0. were calculated from measured

2 2 4

optical densities of two mixtures of NO2 and ^0^ having mole

fractions of N„0, equal to 0.20 and 0.57. A third mixture, X„ _ 2 4 N„0.

2 4 = 0.41 gave good agreement. These measurements agree with those

in (e) and (f) over the regions of wavelength overlap.

63
N0

2 + hv 6

The absorption coefficient data averaged over 10 nm intervals

centered on the wavelength shown are derived from Table 14 of (i)

.

They are based on data in (d) . The entire table covers the wavelength range 290-700 nm and is based on (d) and (e)

.

The selection of the data in (d) is a tentative selection;

work is in progress to measure the absorption coefficient over the

photochemically active region X ~ 400 nm (aa).

Ref. (f) These are the only data for X < 240 nm. They have

been critically reviewed in (x)

.

Ref. (y) Measurements made on a 1.13% ISK^ in ^ mixture at

745 torr total pressure, 23. 9° C, 10 cm path length. High resolution

(0.003 nm) . Results are consistent with the low-resolution data in

(d) within the probable errors of the two studies.

Special Note Recent experiments (S . E. Novick, B. J. Howard,

and W. Klemperer,J. Chem. Phys . 5_7, 5619 (1972) indicate the existence

of the trimer ^Og and possibly higher polymers in the gas phase.

However, N-jOg will not be important in the atmosphere: the total

[N0o] is to small. If these recent experiments are verified, the

experimental measurements of equilibrium constants and optical absorption

coefficients must be reanalyzed. Any effects of polymers will be more pronounced at low temperatures and at high pressures of NO2 . The

spectrum of N3O6 is not known.

It is our conjecture that the present absorption coefficients for NO2

are good (^ 15%) for X > 300 nm but that the data for shorter wavelength

regions may require revision.

64
NO 4-

b . Primary quantum yield for 0 atom production, 0(0)

Ref. (g) In order to deduce the value of 0(0) from the measured

value of §(N0), it is necessary to assume a mechanism of photolysis

of N02> It is well established (h, &) that for X < 398 nm and at

low conversions and low pressures, the mechanism is:

N0

2 + hv -* NO + 0

0 + N0

2 NO + 0

2

3 6 Isotopic scrambling experiments with 0

2 showed the production of a

free oxygen atom at X < 410 nm. Similar results have been found by

other workers (h, k-1). This confirms the above two-step mechanism

for this wavelength range. For regions where this simple mechanism

is applicable, 0(0) = (1/2) x $(N0). The preferred values of 0(0)

were derived from the values of £(N0) in (g) according to the

following scheme:

X < 415 nm 0(0) = (1/2) x § (NO)

X > 415 nm 0(0) = exp[ (e x

-3 . 115) /0 . 043 ]

where = 123 9.8/\(nm) is the photon energy in ev, 3.115eV corresponds

to 398 nm, and 0.043eV is the e-folding parameter in region B in Figure

The small non-zero values of $ (NO) at X ~ 440 nm are suggested by

the authors to result from reactions of N0

2 to produce NO but not

free 0 atoms. At this wavelength the photon energy is 0.3 eV

( i.e. approximately 12 kT) less than the energy required to dissociate

NO. into NO and 0.

65
N0

2 + hv 8

5 . Discussion

This section summarizes interpretations of the photochemistry

of NO^ and describes related work on excited states and fluorescence.

I. Primary Photochemical Processes in Various Wavelength Regions.

a) X < 250 nm

Wavelength threshold for 0(^"D) production is 244.1 nm.

Lines are sharp in band at 249.1 nm and broadened in band at 245.9 nm,

while the bands at 244.7 nm and beyond are diffuse. Broadening of

lines for X > threshold wavelength used as argument against correlation

of absorption in this region with 0(^D) formation (j).

Chemical evidence from photolysis at X = 228.8 nm shows

that of oxygen atoms produced, 40% are 0(^"D) (k2) . Photo-oxidation

of butene-1 shows a change in mechanism between 228.1 and 253.7 nm,

suggesting 0(^D) formation at 228.8 nm (k3)

.

If the broadened bands at 245.9 nm do correlate with

formation of 0(^D) then absorption from internally excited NO2 may

be involved.

b) 250 < X < 398 nm

2 3 N0

2

-» NO (X tt) + 0( P) throughout this region. For

discussion of complex mechanisms of photolysis see (h) and ( f) .

66
N0

2 + hV

Addition of high pressures of N

2 reduces the total quantum

yield in this wavelength region. This effect is partly due to

changed rates of secondary reactions and partly due to quenching

of the upper state formed in the photoabsorption act (cc) . The

latter (quenching) has a negligible effect on the primary process

for pressures less than 1 atm. The former is significant at 1

atmosphere of N2> $(P=0)/$(P) ~ 1.27, due to the process:

0 + N0

2 + M -> N03 + M

N0

3 + NO -» 2N0

2 competing with 0 + N02

-> 0

2 + NO

c) \ > 398 nm

3 Threshold for 0( P) production is 398 nm. Some residual

oxygen atom production at longer wavelengths by absorption from

internally excited N0

2 (h) or by collisionally induced dissociation

of N0

2 (g) . Otherwise absorption in this region results in formation

of N0

2 the dominant fate of which is fluorescence or collisional

quenching. In presence of 0

2 , N02 can undergo energy transfer to

give 0

2

( 1Ag) (z)

.

Under high resolution, lines in the absorption spectrum are

sharp for X > 397.9 nm and diffuse at shorter wavelength (m) . This

onset of diffuseness is in excellent agreement with the calculated

3 wavelength threshold for 0( P) production. This line spectrum of

N0

2 is very rich. Only a few bands have been analyzed (m) . A. E.

Douglas (private communication) has estimated that there may be

67
N0

2 + hv

100,000 lines in the visible region that may be observed with the

high resolution available with a 10m grating spectrograph. Even

with this resolution many of the lines are blends.

The plot of absorption coefficient versus wavelength, Figure

1, has the appearance of lines superimposed on a "continuum". This

background is not a true continuum but is due to absorption in the

wings of many lines. It is an intrinsic part of the spectrum and

is not due to limitations of instrumental resolution.

A recent discussion of the photochemistry of NO2 is given in

(dd).

II. Excited States of N0

2

a. Lifetime measurements from fluorescence.

Wavelength

Region (nm) State T, \ds Note Ref

.

400-600 2 _ 40-90 1,3 n,o V

458-521 2B? 2,3 p

,B 2> continuum

451-460 2„ 2^ ,, . .... Bp B

2 62-75 4 (bb)

Notes

:

1. Excitation primarily by Hg lines. Lifetime dependence

upon exciting \ both found (n) and not found (o)

.

2. Excitation by laser lines. Fluorescence spectrum shows

vibrational and rotational structure and continuum (p)

.

68
N0

2 + hv

3. The number of upper electronic states is in question.

One mechanism is in (o3) . A recent theoretical treatment of the

potential energy diagram is in (q)

.

Discussions of the transitions in the absorption

spectrum of NO,, are in (r) and (s)

.

4. This detailed study using a tunable dye laser shows

a structure of lifetimes as a function of wavelength. The

conclusion is that the shorter life times (t = 40-60 |J.s)

reported in the literature are due to geometrical effects.

Earlier experiments are discussed in detail.

JL 2 b. Quenching of N0

2

"

( B

2

) fluorescence by various gases

NO • X = 436 nm (exciting wavelength)

2 E NO X_, = 470 nm (fluorescence wavelength)

2 F

M

N

2

°2

NO

NO,

CO,

H

2 0

3 -1

a ,(cm molecule ) M

3.4 x 10

3.7

6.2

7.7

8.1

21

-15

k ,(cm^molecule ''"s )

0.62 x 10

0.67

1.1

1.4

1.5

3.8

•10

69
N0

2 + hv

Notes

:

The quenching constant am is defined by the equation:

1. a, = ,, x T , for the mechanism:

M Q,M rad

NO " -> N0 o + hv k , = 1/t - 2 2 rad rad

NO." + M -» N0„ + M k^ „ 2 2 Q,M

2. a(N0„) from Table I of ref. (o3) . Other values of a,, based

2 M

on this value and ratios of a,, (X = 436 nm) in Table II of ref. t M E and arguments therein that a(M)/a(N0o

) is independent of X and X , Z F E

3. k^ ^ calc. from a,, with T = 5.5 x 10

5

s. (o3)

.

Q,M M rad

c. Fluorescence of N0^ in the atmosphere

Based on mechanism in note 1 of section b above, the fraction

of N0^ fluorescing in the presence of quenching gas, M, at concentration [M] is given by:

. = (1 + S a [M])"

1 fluorescing v M M

In one atmosphere of f ~ 1.2 x 10"^ for excitation at

436.0 nm and fluorescence at 470.0 nm.

Total fluorescence per unit volume in sunlight depends upon

incident light flux, absorption coefficient, and all of which

are functions of wavelengths. Data for the calculation not

available

.

70
N0

2

4- hv

d. Photochemistry of N0

2 in Air

To a good first approximation the following mechanism controls

the relative concentrations of NC» 2

, NO, 0, and 0

3 in a polluted

atmosphere (i)

-3 -1

NO + hv -* NO + 0 k = 8.0 x 10 s (u)

2 a

3A- 6 2 1 0 + 0 +M-»03 +M k

2 =5.6x 10" cm molecule s ( v)

0^ + NO -» N0

2 + 02 k

3 = 1.6 x 10 ^cm 3 molecule

1 (w)

The specific rate of photodissociation of N0

2 to give 0 atoms by

absorption of solar radiation is denoted by k^ after the notation in

ref. (i).

These reactions are controlling because they are much faster

than any other reactions and involving these species in the polluted

atmosphere. They establish the following stationary-state concentration or intermediates

[0]

gs = ka [N02 ]/k2 [02 ][M] = 1.1 x 10" 7 [N0

2

]

[0

3

] ss = yN02 ]/k

3 [N0]

= 5 x 10

11 x [N0

2 ]/[N0] molecule/cm3

These formulae may be used, as a first approximation, to

estimate [0] and [0^] at any instant for which measurements of [N0

2

]

and [NO] are available.

The lifetime of an oxygen atom in air at one atmosphere,

T(0) = l/k

2 [0

2 ][M], is 12 Msec. This mechanism conserves the sum

[N0

2

] + [NO]. It does not give the rate of input or of destruction

of nitrogen oxides in the atmosphere.

71
N0

2 + h V

References

D. D. Wagman et al, NBS Technical Note 270-3 (Jan. 1968).

C. E. Moore, NBS Circular 467, vol. 1 (1949).

G. Herzberg, "Molecular Spectra and Molecular Structure,"

vol. II. D. Van Nostrand Co. Inc. (1950).

T. C. Hall, Jr. and F. E. Blacet, J. Chem. Phys. 20_, 1745

(1952) .

J. K. Dixon, J. Chem. Phys. 8, 157 (1940).

T. Nakayama, M. Y. Kitamura, and K. Watanabe, J. Chem. Phys.

30, 1180 (1959) .

I. T. N. Jones and K. D. Bayes, private communication. Results

were also presented at the Tenth Informal Conference on Photochemistry, Stillwater, Oklahoma, May 1972.

J. N. Pitts, Jr., J. H . Sharp, and S. I. Chan, J. Chem. Phys.

40, 3655 (1964).

P. A. Leighton, "Photochemistry of Air Pollution," Academic

Press (1961)

.

G. Herzberg, "Molecular Spectra and Molecular Structure,"

vol. Ill D. Van Nostrand Co. Inc. (1967).

K. F. Preston and R. J. Cvetanovic, Can J. Chem. 44, 2445

(1966); J. Chem. Phys. 45_, 2888 (1966); Ber. der Bunsenges

ii fur physikalische Chemie 72., 177 (1968) .

H. Ford, Can. J. Chem. 3_8, 1780 (1960).

72
N0

2 + hv

A. E. Douglas and K. P. Huber, Can. J. Phys . 43_, 74 (1965).

1) S. E. Schwartz and H. S. Johnston, J. Chem. Phys. 51,

1286 (1969).

2) P. B. Sackett and J. T. Yardley, Chem. Phys. Lettr. 6_,

323 (1970).

1) D. Neuberger and A. B. F. Duncan, J. Chem. Phys. 22,

1693 (1954).

2) K. Sakurai and G. Capelle, J. Chem. Phys. 5_3, 3764 (1970).

3) L. F. Keyser, S. Z. Levine, and F. Kaufman, J. Chem.

Phys. 54, 355 (1971).

K. Sakurai and H. P. Broida, J. Chem. Phys. 50_, 2404 (1969).

R. A. Gangi and L. Burnelle, J. Chem. Phys. 55, 843 (1971).

R. A. Gangi and L. Burnelle, J. Chem. Phys. 55_, 853 (1971).

G. E. Busch and K. R. Wilson, J. Chem. Phys. 56, 3638 (1972).

G. H. Myers, D. M. Silver, and F. Kaufman, J. Chem. Phys.

44, 718 (1966).

Demerjian, K. L., Kerr, J. A., and Calvert, J. G., "The

Mechanism of Photochemical Smog Formation," To appear in

Adv. in Environmental Sci. and Technology, J. N. Pitts, Jr.,

and R. L. Metcalf editors, Wiley -Interscience (Vol. 4, 1974).

R. E. Huie, J. T. Herron, and D. D. Davis, J. Phys. Chem.

76, 2653 (1972).

R. F. Hampson, ed . NBS Report 10828 (April 1972).

R. D. Hudson, Rev. Geophys . Space Phys. 9_, 305 (1971).

73
N0

2 + hv

y) Wilkerson, T. D., Ercoli, B., and Tomkins, F. S. "Absorption

Spectra of Atmospheric Gases" University of Maryland and

Argonne National Laboratory Report to Stanford Research

Institute (January, 1973). Data available from T. D.

Wilkerson, Institute for Fluid Dynamics and Applied

Mathematics, University of Maryland, College Park, Maryland

20742.

z) I. T. N. Jones and K. D. Bayes, Chem. Phys . Lettrs 1J_,

163 (1971).

aa) A. M. Bass and A. H. Laufer, Physical Chemistry Division,

National Bureau of Standards (private communication).

bb) P. B. Sackett and J. T. Yard ley, J. Chem. Phys. 5_7, 152

(1972)

.

cc) H. Gaedtke, H. Hippler and J. Troe, Chem. Phys. Lettrs 16 ,

177 (1972).

dd) K. F. Preston and R. J. Cvetanovic, "Decomposition of

Inorganic Oxides and Sulfides", in "Comprehensive Chemical

Kinetics," ed . C. H. Bassford and C. F. H. Tipper, Elsevier

Publishing Co (1972) vol. 4 pages 47-141.

R. F. Hampson

D. Garvin

January, 1973

74
NO

2 + h V

Figure 1.

Absorption coefficients

k = (1/pX) log 10 (Io/I)

N0 o and No 0, at 25 C. where

p is the pressure m torr

at 25 C and ^ is the path

length in cm. HALL, BLACET, 1952 (d)

(reprinted with consent

of authors)

75
NO- + hv

IOOO

O

LUO

Lu

Ll_ LJo

o

lilt I

100

0_

£TOCO

CO 01

1083 ev

uoo

n

9 76 ev

I

J L J L WAVELENGTH (A)

Fig. 2a. Absorption coefficient (I) and ionization coefficient

(II) of N0

2 in the region 108-130 nm.

2

o

o

2 200

CL

sr. o

cr> ca<

nil 1 1.

1

»' in'

BOO i400 1500 WAVELENGTH (A)

1600

Fig. 2b. Absorption coefficient of in the region 130-160 nm. NOTE : In Fig. 2a-d, the absorption coefficient, k, is defined as: k = (1/j?,) log

e

(I Q /l) where I, in cm., is the layer thickness of the

absorbing gas reduced to 273 K and 1 atm pressure.

76
NO. + h v 19

tOGO

«00 1900 WAVELENGTH (A)

Fig. 2c, Absorption coefficient of NC^ in the region 160-200 run,

100

2000 2200 2200 2400 2500 WAVELENGTH (A)

2600 2700

Fig. 2d. Absorption coefficient of NO^ in the region 200-270 nm. Dashed curves are suggested continua, and circles are some values

by Hall and Blacet.

NAKAYAMA, KITAMURA, WATANABE, 1959 (f)

NOTE : In Fig. 2a-d, the absorption coefficient, k, is defined as: k = (1/JL) log (I /I) where f, in cm., is the layer thickness

of the absorbing gas reduced to 273 K and 1 atm pressure.

(Figures 2a-d reprinted with permission of American Institute of Physics)

77
NO.., + h v

20

o

o

78
Chemical Kinetics Data Survey

The Bimolecular Reaction between N0 0 and 0( P)

1.

2.

o = -192 kj mol

-1

(-45.9 kcal mol ) 298

3 . Data

a. Prior to the review of Baulch, Drysdale, and Horne (b)

,

dated July, 1970, this reaction had been studied over the temperature

range 278-543 K in discharge flow systems, at 300 K in flash

photolysis-flow systems, and at 298 and 410 K in a static flash

photolysis system. Details are given in (b) . Baulch e_t . al . -11 3 recommended the expression = 1.7 x 10 exp (-300/T) cm molecule

over the temperature range 280-550 K.

b . Recent measurements :

3 -1 -1

k^(cm molecule s ) T (K) System

-12

4.4 x 10 300 Flash photolysis of NO (0.15 torr)

in presence of N0„ (1-6 mtorr) and

He (lOtorr) . 0 atom decay monitored

by chemi luminescent reaction

0 + NO -> N0o + hv .

STUHL, NIKI 1970 (c).

79
9.12 x 10" 12 230-339

N0

2 +0 2

- 12 6.1 x 10 298 Discharge flow system. 0 atoms

formed from N + NO reaction.

[N0

2

] = 0.1-1.3 mtorr. [0] followed

by resonance fluorescence . Total pressure =1.3 torr.

CLYNE, CRUSE 1972 (d)

.

Flash photolysis of 0^ (1 torr) in

presence of N0

2 (1-7 mtorr) and

5 torr diluent (N

2 ,Ar) . [0] followed

by resonance fluorescence.

DAVIS, HERRON, HUIE 1973 (e)

.

-12 9.3x 10 296 Flash photolysis of 0

2 (0.1 torr) in

-12

10. 5 x 10 240 presence of NO (0.1 torr), Ar (10 torr)

and N0

2 (0.2-2 mtorr). 0 atom decay

monitored by chemiluminescent reaction

0 + NO -> N0

2 + hv . Flow system.

SLANGER, WOOD, BLACK 1973 (f)

.

kj^/kg [M] = 5.5 Photolysis of N0

2

. [N0

2

] and

where k

2

: NO + 0 + M -» N0

2 + M ^ N2°5 ^ followed bY lon§ P ath I * R -

and [M] = 1 atm N , 297 K. absorption. Molecular modulation

spectrum of N0

2 measured.

HARKER, JOHNSTON, 1973 (g)

.

80
k

1 /k

3 [M] = 9.2 x 10

where k

3

: 0 + 0

2 + M -

0^ + M and [Ml = 1 atm air

298 K

N0

2 + 0

Photolysis of N0

2 (1-100 PPm) in

air studied using N0/0„

chemi luminescence detectors

STEDMAN, NIKI, 1972 (h)

.

Recommended rate:

-12 3 -1 -1

k = 9.1 x 10 cm molecule s

Temperature range 220-500 K

Estimated error limits: +207o

Remarks

The rate expression recommended by Baulch, et_ al_ (b) was based

on the data of Westenberg and de Haas (k), Klein and Herron (1), and

Smith (m) . In the flash photolysis experiments of Smith (m) , k^ and

k^ (0 + 1-butene -» products) were each measured relative to k,.

(0 + CS

2

-* CO + SO). The absolute value of k,. was also measured. The

value of k^ reported was equal to (k^/k,.) x k,. . Alternatively, one

can derive the value of (k^/k^) from the reported values of (k^/k<.)

and (k^/k,-) and then combine this ratio with the value of k^ in ref

-12 3 -1 -1

(n) to give the value of k^ to be 7.2 x 10 cm molecule s at

-12 3 -1 -1

298 K and 9.2 x 10 cm molecule s at 410 K. These values agree

with the present recommended rate within the stated experimental

uncertainty (±30%) in ref (m) . In the experiments of Klein and

Herron (1), performed using a discharge flow system coupled to a mass

spectrometer, a sudden decrease in the measured rate constant was

81
N0

2 + 0

4

observed at temperatures below 260 K, indicating that some phenomenon

was complicating the system. If this complication existed unrecognized at the high temperatures used in the kinetic analysis,

this could explain the reported lower values of the rate constant.

The data of Westenberg and de Haas scatter considerably, but

show little apparent temperature dependence. A simple average of

-12 3 -1 -1

the data gives = 8.1 x 10 cm molecule s , which is within

1570 of the recommended value.

Since the review by Baulch, ejt a_l (b) there have been several

investigations of reaction (1) . Stuhl and Niki (c) and Clyne and

Cruse (d) obtained values in reasonable agreement with the

recommended value of Baulch e_t a_l (b) . Davis, Herron, and Huie

(e), however, obtained a higher rate constant which also showed

no temperature dependence. Slanger, Wood, and Black (f) confirmed

this value using an experimental technique similar to that of

Stuhl and Niki (c) . The ratio k^/k

2 (m) in (g) when combined with

32 6 2 1 the value 9.5 x 10 cm molecule s recommended in this report

for k

2 (NO + 0 + N

2

-> N0

2

4- N

2

> (see separate data sheet on NO + 0 + M)

-12 3 -1 -1

gives a value of k^ = 12.8 x 10 cm molecule s . The ratio

k^/k^ [M] in (h) when combined with the values for k^ (0 + 0

2 + M

-12 3

-> O^ + M) in (i) and (j) gives a value of k^ = 13 . 1 x 10 cm

molecule s . These recent results from N0

2 photolytic systems

(g, h) confirm earlier results on similar systems (o, p)

.

82
N0

2 + 0

Since the measurements of Davis, et al_ form the most extensive data

set, and since these data seem to be supported by the most recent

work, we have chosen the rate constant reported in that work as the

recommended value.

A theoretical calculation using the bond energy-bond order (BEBO)

method has been made for reaction 1 (q) . An activation energy

of about 12.5 kj/mol is predicted - at variance with the zero temperature dependence preferred here.

References

(a) D. D. Wagman, et al, NBS Technical Note 270-3 (Jan. 1968).

(b) D. L. Baulch, D. D. Drysdale, and D. G. Home, "High Temperature Reaction Rate Data", Report No. 5 (1970), Dept. of

Physical Chemistry, The University, Leeds, England.

(c) F. Stuhl and H. Niki, Chem. Phys . Letters 7, 197 (1970).

(d) M. A. A. Clyne and H. W. Cruse, J. Chem. Soc. Faraday Trans.

II 68, 1281 (1972).

(e) D. D. Davis, J. T. Herron, and R. E. Huie, J. Chem. Phys.,

58, 530 (1973).

(f) T. G. Slanger, B. J. Wood, and G. Black, Typescript, Stanford

Research Institute (1973).

(g) A. Harker and H. S. Johnston, J. Phys. Chem. 77_, 1153 (1973).

83
N0

2 + 0

(h) D. H. Stedman and H. Niki, "Kinetics and Mechanism for the

Photolysis of N0

2 in Air", typescript (1972).

(i) R. E. Huie, J. T. Herron, and D. D. Davis, J. Phys. Chem.

76, 2653 (1972).

(j) F. Kaufman and J. R. Kelso, J. Chem. Phys. 46, 4541 (1967).

(k) A. A. Westenberg and N. de Haas, J. Chem. Phys. 50, 707

(1969)

.

(1) F. S. Klein and J. T. Herron, J. Chem. Phys. 41, 1285 (1964).

(m) I. W. M. Smith, Trans. Faraday Soc. 64, 378 (1968).

(n) R. E. Huie, J. T. Herron, and D. D. Davis, J. Phys. Chem. 76_,

3311 (1972)

.

(o) H. W. Ford and N. Endow, J. Chem. Phys. 27, 1156 (1957).

(p) E. A. Schuck, E. R. Stephens, and R. R. Schrock, J. Air

Poll. Cont. Assoc. 16_, 695 (1966).

(q) S. W. Mayer, J. Phys. Chem. 71, 4159 (1967).

R. E. Huie. J. T. Herron

January, 1973

84
Chemical Kinetics Data Survey

3 The Termolecular Association of N0

2 and 0( P)

1. N0

2 + 0(

3 P) + M -» N0

3 + M (1)

2. ^298 = " 2 °5 ± 20 W mo1-1 ( ~49 *

5 kcal mol_1 ) ( a )

3 . Data

a. Measurements of the rate of Reaction (1) in competition

with the bimolecular reaction between NC^ and 0:

N0

2 + 0 -> NO 4- 02 k

2 in the steady u.v. photolysis of N0

2 at room temperature.

20 (k^k^ x 1CT

U

3 (cm /molecule) M System

7.7 N

2 Stirred-flow photolysis reactor.

[NO ] = 8-130 x 10

12 molecule/cm3

;

total pressure = 1 atm; X = 366 nm.

Value of k^/k

2 obtained from intercept

of plot of 1/$ (N0

2

) vs. [N0]/[N0

2

].

FOPxD, ENDOW 1957 (b)

1.12 N

2 Static photolysis system.

1.09 C0

2 Effect of total pressure (up to 1.5

atm) on $ (N0

2

) studied. [N0

2

] =

17 3 2 x 10 molecule/cm ; X = 366 nm.

85
NO + 0 + M 2

2

Values of k-^/k,^ are equal to slopes

of 1/? (N0

2

) vs. [M] plots although

not identified as such in paper.

FORD. JAFFE 1963 (c)

1.34 N

2 Effect of addition of 1 atm N2 on

5 (N0

2

) measured. Black light

fluorescent tube used; peak output at

14 3 350 nm. ^N0

2 = 4 x 10 molecule/cm .

SHUCK. STEPHENS , SCHROCK 1966 (d)

1.10 N

2 Effect of P(N2

) on I '(NO ) measured.

17 3 ^N0

2 = 2 x 10 molecule/cm ;

'. = 366 nm.

Pressure range: 0.3 to 200 atm. k^

found to be 3rd order up to 10 atm and

reached limiting 2nd order value at ~ 100 atm.

TROE. 1969 (e)

1.36 C0

2 Effect of total pressure up to 2.2 atm

16.6 C^2 C *2 ° n * ^2^ ^ rom photolysis of N0

2 at

313 nm measured. [N0

2

: = 2 x 10^

molecule/cm . Data for C^R^, C-jHg,

and i-C^H^Q as third bodies not quoted

here; values are suspect because of

reactivity with atomic oxygen.

BLACET. HALL., LEIGH TON 1962 (f)

86
N0

2 + 0 + M

1.18 AIR Photolysis of N0

2 in 1 atm. air wi th

black-light fluorescent lamps. f^Og]

13 3 ~ 3 x 10 molecule/cm . NO produced

monitored by its chemiluminescent reaction

with 0^ • Value of k^/k^ calculated

from expression: -d In [N0o ]/dt =21/ z. a

[ 1 + k^ [M]/k

2

] Absorbed light intensity,

I , determined separately from initial

rate of photolysis of N0^ in 0^

.

STEDMAN, NIKI 1972 (g)

15 3 0.89 N

2 Photolysis of N0

2 (10 molecules/cm )

in N

2 (1 atm) with black light in 67

liter quartz tube. [N0

2

] and [N

2 0 ]

measured by i.r. absorption. Value of

k^/k

2 derived from d[N02 ]/dt; values

agreeing within 10% derived separately

from d[N

2 05 ]/dt.

HARKER, JOHNSTON 1973 (h)

87
N0

2 + 0 + M

Flash photolysis studies of reaction (1):

(k

1 [M] + k

2 )/k

3 P(M)/torr System

1.8 100 0 atoms from flash photolysis of

4.2 700 N0

2 (X > 300 nm) . M = Ar. [N0

2

] ~ 10"*"^ - lO

1 ^ molecule/cm3

. Total

reaction of 0 atoms with N0

2 by

(T = 298 K) both channels ( (1) + (2) ) competes

with reaction with CS

2 (3). [CS]

(kg : 0 + CS

2

~* CS + SO) monitored by absorption at 257.6 nm.

Data also given for T = 410 K.

SMITH 1968 (i)

[M] + k

2 P(M)

3 -1-1

(cm molecule s ) £torr) 0 atoms from flash photolysis of 0

2

. -12

10.6 x 10 200 Resonance fluorescence used to monitor

11.7 x 10" 12 400 atom decay by overall reaction with N0

2 in both channels ( (1) + (2) ).

k

2 = 9.1 x 10

12

M = Ar. [NO.] ~ 10

14 molecule/cm

3

(T = 298 K) Data also given for T = 263 K and

230 K.

FUIE 1972 (j)

88
N0

2 + 0 + M 5

4. Preferred Value

-20 3 k

x (M = N

2

) = 1.1 ± 0.4 x 10 cm /molecule at 298 K

~2

k^ = 1.0 ± 0.5 x 10 cm^ molecule ^s

-12 3 -1-1

based on = 9.1 x 10 cm molecule s (value recommended

in separate data sheet on 0 + N0

2

~* NO + 0

2

) .

5 . Remarks

In the experiments involving the ultraviolet photolysis of

nitrogen dioxide, the relative rate constant for reaction (1) was

derived from the experimental quantum yields using the mechanism for

the photolysis of N0

2

:

N0

2 + hv -» NO + 0 ( 3 P)

0 + N0

2 * NO + 0

2

0 + N0

2 + M -» N03 + M

0 + NO + M -> N0

2 + M

N0

3

+ NO -* 2N0

2

O + 0

2 +M-*O3 +M

0

3 + NO -» N0

2 + 02

N0

3 + N0

2

-> N

2 0

5

and assuming steady state values for 0, N0

3

, and 0

3

. Depending on

the species being monitored and on the experimental conditions, various

expressions leading to the ratio k^/k

2 may be derived.

«Q
N0

2 + 0 + M

The recommended value for k-^/k^ is the simple average of the

values (for M = ^) from references c, d, e, g, and h. These values

all lie within about 207o (one standard deviation) of the average

value. The only value which deviates significantly is from reference

(b) . The data from which this value was obtained, however, show

considerable scatter, and the derived value of the ratio is quite

sensitive to small changes in the intercept of the plot, so that this

value is rejected.

Comments on measurements

Ref (i)

.

In this work, consistent results were unobtainable without

the addition of NO, presumably to remove NO^ . The derived value of

k^/k

2 at 298 K given there is a factor of eight higher than that

recommended here. It is possible to derive the relationship:

-19 3 k

l

//k3 = 1,2 X 10 cm /molecule from the data at M = 100 and 700

torr. With the absolute value of k^ measured in the same study

-12 3 -1 -1

(k^ = 4.0 x 10 cm molecule s ), one can derive a value of

316 2

— 1 k^ = 5 x 10 cm molecule s , almost a factor of five higher

than the value of k^ recommended here. In view of the complications

in this system, these results are rejected.

90
N0

2 + 0 + M 7

Re f ( j )

.

The only direct measurement of k^ reported is from

reference (j). Although there were no apparent complications in the

system, the procedure involved measuring a small (20-307o) change,

due to the contribution of reaction (1) in a large second order rate

constant. At room temperature, the reported value of was about

a factor of two higher than that recommended here. The temperature

dependence of the reaction derived from these data is about T , -3/2 v which is far steeper than would be expected (~ T ) based on RRKM

calculations on other atom-molecule addition reactions (k) . These

calculations also indicate that the observed pressure effect reported

in (j) at 230 K is too sharp.

References

(a) D. D. Wagman, W. H. Evans, V. B. Parker, I. Halow, S. M.

Bailey, and R. H. Schumn, N. B. S. Tech. Note 270-3. Data on

N0^ from JANAF Thermochemical Tables (1965).

(b) H. W. Ford and N. Endow, J. Chem. Phys . 27_, 1156 (1957).

(c) H. W. Ford and S . Jaffe, J. Chem. Phys. 38, 2935 (1963).

(d) E. A. Schuck, E. R. Stephens, and R. R. Schrock, J. Air

Pollution Control Assoc. 1_6,695 (1966).

(e) J. Troe, Ber. Bun. Phys. Chem. 73, 906 (1969).

(f) F. E. Blacet, T. C. Hall, and P. A. Leighton, J. Amer. Chem.

Soc. 84, 4011 (1962).

91
N0

2 + 0 + M

(g) D. H. Stedman and H. Niki, "Kinetics and Mechanism for the

Photolysis of N0

2 in Air", typescript (1972).

(h) A. Harker and H. S. Johnston, J. Phys. Chem. 77, 1153 (1973).

(i) I. W. M. Smith, Trans. Faraday Soc. 64, 378 (1968).

(j) R. E. Huie, Ph.D. Thesis, University of Maryland (1972).

(k) W. Tsang, Private Communication (1973).

R. E. Huie

J. T. Herron

March, 1973

92
tt 2 0

5 + hv

No 0 c PHOTOCHEMISTRY

Reaction kJ /mo

1

(Kcal/mol) \ threshold (nm)

3

N2°5 "* N2°4 + 0 ( P) 242 57.8 495

^2 5 2 4 \ u )

L+ ~) £. J. UJ • Z_ 1 U

N2°5 N2°3 + °2 u u IS Q 1lOUU ftftft

N2°5 * N°3 + N°2 90 21.4 1300

AHq calculated using £H° values in ref [a] (except for AH° (N0

3

) which is from

JANAF tables but consistent with ref [a]) and excitation energy of 0(

1D) from ref

2. Data : 2a. Absorption Spectrum

Wavelength Range Observation

ultraviolet continuous absorption beginning

at about 305 nm extending into

the Schumann region

UREY, DAWSEY, RICE, 1929 [c]

450-250 continuous absorption 450-320nm

transparent 320-280 nm. continuous absorption A<280 nm. NOTE : N0

2 always present

DUTTA, SEN GUPTA, 1933 [d]

93
N

2 0

5 + hv

2b . Absorption Coefficient

Wavelength Range Data

9 ft K /< ^ ft T>m A (nm) k

(selected Hg lines) 265 2.1

280 0.96

302,313,334 ZERO

366,405,436 ZERO

Unit

-1

1 cm (atm at 273 K)

base 10

285-380 nm.

HOLMES, DANIELS, 1934 [e]

Value of k rises

steadily from

k=0.002 at 380 nm to k=0.52 at

285 nm. See FIG. 1 JONES, WTJLF, 193" [f]

1 cm~

1 (atm at 273 K)

base 10

Fig. 1. Absorption coefficient of N„0 , -1 -1 285-380 nm in units of cm (atm at 273 K)

base 10 (From E. J. Jones and 0. R. Wulf,

J. Chem. Phys. 5_, 873 (1937), reprinted with

consent of authors)
N

2 0

5 + hv 3

2c . Quantum yields

$ j["^O^) = net quantum yield for disappearance of N

2 0

5

X (nm) 1' (-N„0 v C ) 2 5'

p

N2°5

280 0.6 51 torr, 0°C

280 0.6 eq . v.p. 10°r

265 0.6 51 torr, 0°C

HOLMES , DANIELS, 1934 [e ]

280 0.62

MURPHY, 1969 [g]

14-51 torr, 0.2 °C

Effect of added inert gas on value of $(-N2 0

5

)

M PM

(torr) * (-N

2 05

) PN 0 (t0rr)

2°5

SF

6

110-620 0.50-0.32 25-30

110-600 0.59-0.36 35-40 X=280nm

N

2

100-600 0.62-0.55 18-25 t=0.2°C

°2 100-600 0.53-0.29 a 30

MURPHY, 1969 [g ]

Because ^(-N^O,.) < 1 and decreases with increasing pressure of inert gas

the photoabaorption act is believed to form an excited molecular state

that can either dissociate or be quenched upon collision. The initial

photodissociation products are unknown. The relationship between the

overall ^ and the effective *jJ for photodissociation depends upon the

extent of reaction of products of photolysis with N^Oj. . See section 4

for one mechanism.

95
N

2 0

5 + hv 4

3 . Recommended values.

3a . Absorption coefficients.

380-285 rim. Values shown in Fig. 1 (from [f] )

280 and 265 nm. Values in section 2b (derived from [e] ) 2 To convert values given in 2b into cross sections in cm molecule

-20

(base e) multiply by 8.57 x 10

3b . Quantum yields

According to mechanism of ^O,. photolysis given in section 4, the

ry quantum yield for proc

From the data of ref. [g

primary quantum yield for production of 0 atoms, fy^ = 0.5 x $ (-^0^.)

Q

= (3.12 + 0.00084 PN + 0.0058 P

Q

) ~ l

where Pjt and P are expressed in torr.

2 U

2

4 . Remarks

The mechanism proposed for the photochemistry of pure is:

N2°5 (S o

) + hv ~* N2°5* (S 1

)

N2°5* (S 1

5 "* N2°5* (T

1

}

N

2

0

5* (T

x

) * 1^0 + 0

No 0_* (T ,) + M -> N 0 + M

2 5 1 2 5

0 + N

2 0

5

-» N

2 0

4 + 0

2 (or 2N0

2 + 0

2

) .

By this mechanism, the limiting low pressure primary quantum yield

for the production of 0 atoms is one-half the value of $ (-N^O,-) obtained

in the absence of inert gas, i.e. 0.5 x 0.62 = 0.31.

96
N

2 0

5 + hv

References

[a] D. D. Wagman et al, NBS Technical Note 270-3 (Jan. 1968).

[b] C. E. Moore, NBS Circular 467, vol. 1 (1949).

[c] H. C. Urey, L. H. Dawsey, and F. 0. Rice J. Am. Chem. Soc. 51,

3190 (1929).

[d] A. K. Dutta and P. K. Sen Gupta Proc. Roy. Soc. (London) A139 ,

397 (1933).

[e] H. Holmes and F. Daniels J. Am. Chem. Soc. 56, 630 (1934).

[f] E. J. Jones and 0. R. Wulf J. Chem. Phys . 5, 873 (193 7).

[g] R. F. Murphy, "The Ultraviolet Photolysis of the Nitrogen Oxides,

Dissertation, U. C. L. A. (1969).

R. Hampson

Nov. 1972

97
Chemical Kinetics Data Survey

Photolysis of 0,2

1 . Primary Photochemical Transitions

Reaction kj/mol (kcal/mol) X threshold (nm)

2 CL -> 0(

3 P) + 0(3 P) 493.57 (117.97) 242.4

-» 0(

3 P) + 0(V> 683.39 (163.33) 175.0

-» 0(

3 P) + 0(1 S) 897.81 (214.58) 133.2

(AHq values calculated from AH^ (0) in (a) and energies of excitation

of 0(

1D) and 0(

1 S) in (b)).

2 . Absorption Coefficient Data

Wavelength range Sys tern

< 300 nm Critical review of u.v. absorption

cross section data.

HUDSON, 1971 (c)

175-205 nm Computed absorption cross section

at high resolution of the SchumannRunge bands from (0,0) band at

205 nm to dissociation limit at

175 nm.

i ACKERMAN, BIAUME, KOCKARTS, 1970 (d)

98
0

2 + hV

178-205 nm High-resolution study of

structure of Schumann-Runge

bands from (0,0) to (13,0) band,

t ACKERMAN, BIAUME, 1970 (e)

116-244 nm Table of adopted values of

absorption cross section averaged

over 500 cm ^ intervals

.

ACKERMAN, 1971 (f)

181-235 nm Absorption cross section of the

0^ continuum and its pressure

dependence measured.

OGAWA, 1971 (g)

243-264 nm Absorption measured for eight

bands of the Herzberg I

(A

3£+

- X

3£") system, u g

HASSON, NICHOLLS, 1971 (hi)

192-243 nm Absorption cross section of weak

photodissociation continuum

adjoining the Herzberg I system

measured over 109 ft. path length,

HASSON, NICHOLLS 1971 (h2)

.

99
0

2 + h v

175-203 nm Band oscillator strengths and

predissociation line widths of

Schumann -Rung e band system

derived. Continuum cross section

calculated from 176-210 nm for

T = 150, 200, 250, and 300 K.

HUDSON, MAHLE 1972 (i)

3 . Photochemical Data

A recent review and compilation of spectroscopic data (including

the u.v. spectrum) of 0^ is given in ref (j).

a) X > 175 nm

al. Spectroscopy (c,k,^,m)

X range

185-260 nm

175-200 nm

Transition

3 + 3 - AT -» XT" u g

3 - 3 . B E -» XT,

u

Name

Herzberg

Continuum

S chumann-Runge

Band System

.3„- The B S predissociates by crossing at about the v

1 = 2 level to

3 the IT state,

u

100
0

2 + h v 4

a2 . Photochemistry

At X = 184.9 nm 0(0) = 2 based on $(0

3

) = 2.0 for ?(0^> 100 torr

(ref n) ($(0^) measured relative to $(N

2

) from ^0 which was taken

to be 1.44). At P(02) < 100 torr $(0^) decreases presumably due to

0 atom wall losses. Such a decrease is apparently an experimental

artifact and not indicative of primary photochemical processes. The

same study at 193.1 nm reports ^(0^) = 0.3 independent of P(02) from

300 to 1300 torr. The explanation requires direct excitation and

subsequent quenching of a rotational line of the S-R continuum. This

is contrary to spectroscopic evidence (c) which indicates that all

of the rotational lines near 193 nm are strongly predissociated.

b) 175 > X > 133.2 nm

bl. Spectroscopy (c)

Absorption consists of the Schumann-Runge (B ~* X) dissociation

3 1 continuum (0( P) + 0( D)) with two superimposed continua bands centered

at 135.2 and 133.2 nm. The former has been suggested to correspond

to the spin-forbidden dissociation of 0^ into two 0(^D) atoms. The

low wavelength boundary of this region corresponds to the thermochemical

3 1 onset for the dissociation into 0( P) + 0( S)

.
0

2 + hv

b2. Photochemistry

Emission from 0(

1D) at 630 nm (0(13

D) -> 0( P)) has been

observed by Noxon (o) in the 147 nm photolysis of 0^. Emission

]_+ i + 3 _ from 0 (b T ) at 760 nm (bT -> X £ ) was also observed. The

^ g g g

1 +

0

2 (b~E

g

) is presumed to be produced in the reaction:

O^D) + 0 (xV) "» 0(

3 P) + 0

9 (bV")

^ g ^ g on the basis of the intensity of the 760 nm emission and assuming

that O^b'tg) is produced in the above reaction with 1007o efficiency,

1 3 an "order of magnitude" calculation indicated that 0( D) and 0( P)

are formed in equal amounts in the primary photolysis of 0^ at 147 nm.

The 147 nm photolysis of 0

2

{ u the presence of K

2 and NO was studied

1 by Young (p). Assuming that 0( D) reacts with but is not quenched

3 3 *

to 0( P) by H2? and that 0( P) reacts with NO to form N0

2 which

1 3

fluoresces, he found that the 0( D) and 0( P) productions are equal.

Other investigators (q, r) have monitored 0^ formation to deduce

thereby total 0 atom quantum yields of 2 but were unable to distinguish

3 1 between 0( P) and 0( D) . The fall-off in $(0^) at low pressure was

also observed in these systems and has been inadequately explained on

the basis of 0(^D) reactions.

102
6

c ) 133.2 > \ > 100 nm

cl. Spectroscopy (c)

A continuum in the Schumann-Runge system centered at 133.2 nm

3 is presumedly due to the onset of the dissociation of 0^ into 0( P)

and 0(^S). The region between 102.7 nm, corresponding to the

ionization potential of 0^, and 130 nm consists of a large number

of strong absorption bands. A narrow window at Lyman-a, 121.56 nm

has been observed repeatedly.

observed in the flash photolysis of O2 between 134 and 105 nm (s).

This emission is enhanced in the presence of Ar, Kr, or Xe. The

quantum yield for production of 0(^S) has not been determined.

c2. Photochemistry

Emission from 0( S) at 557.7 nm (0( S) "+ 0( D)) has been

4. Preferred values

a. Absorption Coefficients

243-195 nm Use data of HASSON and NICHOLLS (h2)

.

210-176 nm a) Continuum cross sections: use

data Table 4 of HUDSON & MAHLE (i).

b) Schumann-Runge bands: use data

in ACKERMAN, BIAUME, AND KOCKARTS (d)

.

103
0

2 + hv

175-135 nm See Figures 13, 14, and 15 of

HUDSON (c)

.

244-116 nm The most conveniently tabulated

data is that given by ACKERMAN i

Table 1 of ref (f) . These are

average adopted values not

significantly different from

values recommended above. They

are given here in Table 1.

b . Quantum yields

bl. 0

2 + hv -> 0(

3 P) + 0(3 P)

200 > \ > 175 nm 0=1

b2. 0

2 + hv -> 0(

3 P) + 0(XD)

175 > \ > 133 nm 0=1

b3 . 0- + hv -» 0 + 0

200 > X > 106 nm 0=1

5. Remarks

No photolytic system studied to date has used wavelengths

corresponding to thresholds indicated in Section 1. Quantum

yields for production of oxygen atoms in specific electronic states

are needed.

104
TABLE 1. Averaged absorption cross section

values (from Ackerman, reference f)

Av (cm ) o(0

2 )(cm )

Lyc* 1.215,67

1.170-1.163

1.176-1.170

1.183-1.176

1.190-1.103

1.198-1.190

1 .205-1.198

1 .212-1.205

1.220-1.212

1.227-1.220

1.235-1.227

1.242-1.235

1 .250-1 .242

1 .258-1 .250

1 .266-1 .258

1.274-1.266

1.282-1.274

1.290-1.282

1.299-1.290

1.307-1.299

I .316-1 . 307

1.324-1.316

1 .333-1.324

1.342-1.333

1.351-1.342

1 .360-1.351

1 .370-1.360

1.379-1.370

1.389-1.379

1 .408-1.389

1.428-1.408

1.449-1.428

82.259

85.500-86.000

85.000-85.500

84.500-85.000

84.000-84.500

83.500-84 .000

03.OOO-83.5OO

82 .500-83.000

82 .000-82.500

81 .500-82 ,000

81 .000-81 .500

80.500-81 .000

0O.OOO-8O.5OO

79 .500-80.000

79 .000-79. 500

78.500-79.000

78.000-78.500

77.500-78.000

77 .000-77 .50D

76.500-77.000

76.000-76.500

75 .500-76.000

75.000-75.500

74.500-75.000

74.000-74.500

73.500-74.000

73.000-73.500

72.500-73.000

72.000-72.500

71.000-72.000

70.000-71.000

69.000-70.000

1 .00 X 10

-?.o

2 .00 X 10'-20

1.25 X 10

-18

2.55 X 10

A J

3.00 10

-20

3.75 IS 10

-19

'» .45 X 10

-18

8.35

6 ,00 X 10

-19

I .30

A r.A

«» . Jl)

j . A D 1.75 X

10"-17

X

1 n" 10

-19

l l n

7 OS

4 it J

5 .55

4 .20

6 .85

1 AS X i n"18

2.30

4.55

7.23

9.50

1.23 si 10" 17

1.32

1.36

1.40

1.48

105
0 + hv

2

TABLE 1 (Continued)

-I 2 A A (A) Av (cm ) o(0

2 )(cm )

,-17

.-18

1 .A 70 - L .449 60 .000-69 .000 1 .41 X

i .492 -1 .A70 67 .000-60 .000 1 .29

-1 .A92 66 .000-67 .000 1 .15

-

1

y) _J t\>\ > \ J >U * K > \ J\J 9 .91 3C

1 .562 -1 .5 30 64.000-65 .000 0.24

1 .507 -1 .562 63.000-64 .000 6.50

1 .613 -1 .507 62 .000-63.000 A. 97

1 .639 -1 .613 6*1 .000-62 .000 3. A 5

1 .667 -1 .639 60.000-61 .000 2. .00

J .60 3 -1 .667 59.000-60.000 1.23

J, -7 2 A -1 .695 ri0 .000-59 .00(1 1 .22 X

J .7 3^ -] .724 57 .500-58.000 A. 50

1 . 7 54 -1 . 7 3') ' ? .noo-r>7 '-o^ 2. 7 A

2 -020 .7 54 49.500-57 ,.noo •ft

2.041 -2 .020 49 .000-49 .500 1.14 X 2.062 -2 .041 48.500-49 .000 1.05

2.003'-2.062 40.000-40.500 1 .00

2.105 -2.O03 47 .500-40.000 9 .55 X

2.120--2 .105 47 .000-47 .500 0.93

2.150 -2 .128 46 .500-47 .000 8.20

2.174 -2 .150 46 .000-46 .500 7.60

2.198--2 .174 45.500-46.000 6.9?

2 .222--2 .190 45.000-45.500 6.20

2 .247--2 .222 44.500-45.000 5.65

2.273 -2.247 44 .000-44 .500 5.03

2 .299--2 .273 43 .500-44 000 4.40

2.326-2 .299 43.000-43.500 3.76

2.353-•2 ,326 42 .500-43 .000 3 .09

2.301-2 , ,353 42.000-A2.500 2.44

2.410-•2 . 301 41 .500-42 .000 1.75

2.439- 2 , 410 41.000-41.500 6.74 X

.-19

.-23

•24

-2 5 
0

2 + h v 10

References

a. D. D. Wagman et al, NBS Technical Note 270-3 (Jan. 1968).

b. C. E. Moore, NBS Circular 467, vol. 1 (1949).

c. R. D. Hudson, Rev. Geophys . Space Phys . 9_, 305 (1971).

i d. M. Ackerman, F. Biaume, and G. Kockarts, Planet. Space Sci.

18, 1639 (1970).

e. M. Ackerman and F. Biaume, J. Mol. Spectrosc. 35_, 73 (1970).

I f. M. Ackerman, "Ultraviolet Solar Radiation Related to Mesospheric

Processes," Aeronomica Acta No. 77 (1970). Available through

National Technical Information Service, N71-13825. Also published

in "Mesospheric Models and Related Experiments," G. Fiocco, ed.,

D. Reidel Publ. Co. (1971).

g. M. Ogawa, J. Chem. Phys. 54, 2550 (1971).

h. V. Hasson and R. W. Nicholls, J. Phys. B: Atom. Molec. Phys.

4, 1778 (1971); ibid. 4, 1789 (1971).

i. R. D. Hudson and S. H. Mahle, J. Geophys. Res. 77j 2902 (1972).

j. P. Krupenie, J. Phys. Chem. Ref. Data I, 423 (1972).

k. P. K. Carroll, Astrophys. J. 129, 794 (1959).

1. D. H. Volman, Advances in Photochemistry I, 43 (1963).

m. J. G. Calvert and J. N. Pitts, Photochemistry , p. 205

(John Wiley & Sons Inc. 1966).

n. N. Washida, Y. Mori, and I. Tanaka J. Chem. Phys. 54, 1119 (1971).

o. J. F. Noxon, J. Chem. Phys. 52, 1852 (1970); ibid 57, 1033 (1972).

107
0

2 + hv

p. R. A. Young, G. Black, and T. G. Slanger, J. Chem. Phys

.

49, 4758 (1968).

q. J. 0. Sullivan and P. Warneck, J. Chem. Phys. 46, 953 (1967)

r. M. Clerc, A. Relffsteck, and B. Lesigne, J. Chem. Phys. 50,

3721 (1969).

s. S. V. Filseth and K. H. Welge, J. Chem. Phys. 5_1, 839 (1969)

A. H. Laufer

May 1973

108
Appendix A

Reactions of Potential Interest for the Chemistry

of the Stratosphere

(Revised May 1973)

This list of reactions is based on several sources. It includes

those used in models by P. J. Crutzen, J. Geophys . Res. 76., 7311 (1971),

Univ. of Stockholm Meteorology Report AP-6 (1971); by H. S. Johnston,

Science 173, 517 (1971), UCRL Report 20568 (1971), MS. "Formation and

Stability of Nitric Oxide in the Stratosphere" (July 1971) , and mentioned

in discussions; those considered important by J. London and H. U. Dutsch,

letter from J. L. to D. G., Oct. 19, 1971; and other reactions considered

in studies at NBS.

The reactions are arranged in alphabetical order by first reactant.

Notes on entries in the Table:

1. Importance in Stratosphere . An asterisk in this column indicates

that a student of the atmospheric modelling problems considers this reaction

to be important. Absence of a mark does not imply the opposite.

2. Status of Data . An asterisk in this column indicates that an

evaluator or modeller considers that better measurements are needed. Other

remarks indicate the reliability of the data as assessed by an evaluator.

Absence of a mark or comment has no significance.

3. Evaluation . References to recent evaluations are given here.

The listing may not be complete. The notations are identified below.

a. R. F. Hampson et al, "Survey of Photochemical and Rate Data

for Twenty-Eight Reactions of Interest in Atmospheric Chemistry", to appear

in J. Phys. Chem. Ref. Data _2, No. 2 (Summer 1973). (Updated versions of

evaluations in NBS Reports 10692 and 10828)

.

109
b. R. F. Hampson et al, NBSIR 73-207, May 1973, (this report)

c. D. Garvin, editor, NBSIR 73-203 (May 1973).

d. D. Garvin, editor, NBSIR 73-206 (May 1973).

e. D.L. Baulch, D. D. Drysdale, D. G. Home, A. C. Lloyd,

"Evaluated Kinetic Data for High Temperature Reactions, Volume 1,

Homogeneous gas phase reactions of the H^-O^ system", Butterworth

and Co. , London (1972)

.

f. H. S. Johnston, Nat. Stand. Ref. Data Ser. - NBS _2_0 (1968)

g. A. C. Lloyd, NBS Report 10 447 (July 1971).

h. K. Schofield, J. Phys. Chem. Ref. Data 2, 25 (1973).

i. W. E. Wilson, Jr., J. Phys. Chem. Ref. Data 1, 535 (1972).

110
Reaction

Import

,

in

Strat.

Status of Data

A log k

Evaluation

CH

4 + 0( D) * CH3 + HO ±0.1

CO + HO ^ C0

2 + H ±0.1

H + HNO + H

2 + NO upper limit only a, d

H + HN0

2 + Products no data

H + HN0

3

-> Products upper limit only

H + H

2 02

-> H

2 + H02

H + N0

2

-* HO + NO

±0.3

±0.1

e , d

a, d

H + 0

2 + M -*> H02 + M ±0.07

H + 0

3

-* HO + 0

2

+ 0.1

HNO + HO -> H

2 0 + NO ±0.7(T>1600K) a, d

HN0

2 + HO + H

2 0 + N02

HN0

2 + 0 -> HO + N0

2

no data

no data

HN0

2 + hv ** Products

HN0

3 + HO -» H

2 0 + N03

no data

±0.5

HN0

3 + 0 + HO + N03 upper limit only

HN0

3 + hv -> HO + N0

2 a data only

HO + HO -> H

2 0 + O ±0.2

HO + H0

2

-> H

2 0 + 0

2

HO + H

202

-> H

2 0 + H0

2

±1

±0.1

g,e,c

b , e

111
Reaction

Import,

in

Strat.

Status of Data

A log k

Evaluation

HO + NO + M -> HN0

2 + M

HO + N0

2 + M -* HN0

3 + M

HO + 0 -> H + 0„

±0.5

±0.3

±0.3

b

b

e,i

HO + 0

3 ^ H0

2 + 02 H0

2 + H02 + H2 0

2 + 02

±0.3

±0.3 a,e

H0

2 + NO -* HO + N0

2 ±0.5

H0

2 + NO + M -> HN03 + M

H0

2 + O -> HO + 0

2 ±1.

H0

2 +

°3 H° + 2 °2 ±0.3

H0

2 + hv -> HO + O a ± 30%

some (J> data

H

2 0 + NO + N02 * 2HN02 upper limit only

H

20 + N

2 0

5

-> 2HN0

3 upper limit only

H

2 0 + 0( D) -> 2H0 ±0.1 d,a

H

2 0 + hv * HO + 0

H

2 0

2 + NO + HO + HN0

2

H 0

2 + hv > 2H0

NO + NO + 0

2

-> 2N0

2

upper limit only

a, ij)

±0.2

NO + N0

2 N2 0

3

NO + N0

3

-> 2N0

2 ±0.7

112
Reaction

Import,

in

Strat.

Status of Data

A log k

Evaluation

NO + 0 + M + N0

2 + M

NO + 0

3 + N0

2 + 0

2

NO + hv -* N + 0

±0.2

±0.11

fragmentary data

b,d

a ,d

b

NO + M^N + O + M questionable data

N0o + NO„ + M * No 0. + M :0.2

N0

2 + N0

3 + NO + N02 + 02 0.4

N0

2 + N0

3 + N

2 05

N0

2 + 0 > NO + 02

N0

2 + 0 + M * N0

3 + M

N0

2 + 0

3 > N03 + 0

2

N0

2 + hv -> NO + 0

N0

3 + N0

3

-> 2N0

2 + 02

N0

3 + hv * N0

2 + 0

±0.1

±0.3

±0.2(1=298 K)

±0.5

±1

b

b,d

a,d

b

d

N0

3

-> N0

2 + 0

N

2 0 + 0( D) * N

2 + 02 0.1 d,a

NO + NO

N

2 0 + hv hc N

2 + O( D)

N

2°5 + °

"** 2N0

2 + ° upper limit only

N

2 0

5 + M N02 + N0

3 + M ± 0.3 d, c

113
Reaction

Import

.

in

Strat.

Status of Data

A log k

Evaluation

No 0 c + hv -> ? 2 5 * fragmentary data b

* NO -> NO + NO

2 5 2 3 NOVi + M ^ N 0 +M 2 ^ ^

' * 2 5 *

0 + 0 + M-»-0„+M * ±0.3 f

0 + 0_ + M 0 o + M

2 3 * ±0.07 c

0 + 0 o

-> 20„ ±0.1 a , c

o^d) + o

2 > o + o2

C

1 V

±0.1 d

u(, u; + ^ + u

2

i

1 ±0.3 d

0( D) + 0„ -> 20„

OC^D) + M -> 0 + M * ±0.1 (except M=0 ) d

0 o + hv -> 0 + 0

2 * o , <f> b

0

2 + M->0 + 0 + M ±0.3 f

0

2

( 1 A) + 0

3

-y 0 + 20

2 ±0.05

0

2

(

1 A) + M -> 0

2 + M ±0.1 (M = 02

) a upper limit only (M=N

2

)

r\ / 1 v"^"\ -L r\ _jw r\ _i_ on u 0

( l ; + o -> u + 20

2 g 3 2

1 TUT

O^ 1 !"1") + M -> 0„+ M

2 g 2 ±0.1 a

0

3 + hv -> 0 + 02 * a, (j) a

114
Appendix Conversion Tables

Equivalent Second Order Rate Constants

Equivalent Third Order Rate Constants

Conversion Factors for Units of Molecular Energy

Units of Optical Absorption Coefficients (Discussion)

Conversion Factors for Units of Optical Absorption Coefficients

115
rH rH ,—1 1 | rH I 1 £H Eh 1 H

CO

H cr. CO

rH 1 1 rH 1 co O co O CO <r o O o> o in o r-I O <r r-i O vO rH

CM CM o CMm 00 rH

C\J

xX CM

X

X VO

g r—t r-| rH i

0*1 1 c in

•H i£> CO U"> CM i CO a 1 1 H 1 o

co o CO o CO

O QOO o rH OV

O

m rH

m tH in rH l~~ rH vO rH

«a- in

X rH o x X X x

p, CM CM rH VO vO

r—|

rH

r-I

H

i—t 1 | Eh CM H H rH

m

w •a- CM vT CM

rH OA o o\ o\ o o r»

O CO 1 rH r-I r-I rH iH ~T rH VO rH

CM CM CO o •H vO rH X CM X X vO • X O

CO (H i—l rH rH rH

r-II tfl rH rH

rH I rH | I H H 1 Eh m CM E-t oo CO

'to 1 1 rH CO

EC <r

O -T

O <T oo o vO o CO CO o r-I O rH O HO rH iH rH cr> CO

vo VO vD CO rH

Jj,

XX vO • X

X rH rH r-I rH u\ t iH CM o

r—|

rH| EH

H Eh <r rH CO cn CM VO o 1—I

CM CM rH iH CM rH I I I o o o o in o CM o o o

0) vO r-I rH VO rH CO rH VO rH rH CO 1—1

tH lO vO vD rH

O CO CO o X X X X X • X a iH r-I rH iH iH vO rH E

L»

r-I • 1 H H

H CO r

CM in CO

r-t i—1 1 1 1 co O VO O vD 'o -T o rH lO CO CM rH CO iH O •H H rH o 1 1 O CM CM CO 6 o o rH X X X O ro 1—1

1—1 vO co CO e

rH

CO Eh rH o Eh CM Eh 1 CM 1 m rH CO O id vO o o *j O CO CM rH CO o iH rH rH g 1 CO o CM CO PI o iH o CM X °. X B I—1

rH 10 vo 00 00

T3

i—( 1 CO CO E-t

H

1—ICM *cr 00 Eh 1 CO O vO O vo r-» o o *T O CO O CM O H a o O X X CM • X CO

CO rH r-I rH vO vO co 00 B

cj

II

—1

II 1 03 || pQ || rH # H 1 rH II E cj iH rH CJ I II / 1 rH rH GO II •H co 3

01 01 I 3 rH 1 01 rH

1-1 rH CO r_> I rH

C

H 0) I / 1 1 rH QJ •H CJ 01

r-I rH I rH 00 01 E " rl rH / O O H O EC H ih x a, 1 E E O E 1 1 00 co CO B CO E E o\ H 5 E E CO E 4J o- cm nj CN < u T3 E o co D. 4-1 s u o

r-I

H rH rH rH rH rH egu r-I 2a

-a

p;

<c

cu

4J *

jj o

L|_) o .

CP* ? 1 o Qg

j_) E c •H

•r-I

eoi W|

4J

H

QJ

u *^ c Q

r-I z o5 CO o CO jj

JJ

g CO (h ^ t a) w jj

cO

•r-| Cd o o

14-1 •H o JJ

4J

4J CO

Ml cjO Si

CD aj OJ 3O

jj jj

a (0 Q rH n g

4J 3 H

R)

'co tU3 ;> 00 3 •H n rrj O B

0J 0

LJ a>

u

«0 MH M jj •o

CO 0J rH U U a a

*H (S

<U jj •o

r> rH <0 CO E 0) u rH

T3 •a o C H CO

116
117
4 3U

CDo>Vt3o

no

O ° o y, 00o

CMi S «

CO

03P 3 CMoo

05 I

CM

0}to

CO

COo

c-C0

O0

CM

CM

COI 3 x

ino o

co

r-oo

CM

OO—< 31—1 "5 X

CO

CD

CM

inca

Oio£ oo

CO

CM

co£

CD

CO: )

oo

CNJ

O CO

O uo

CM trj uO CO

If} CM

oo CM o

COCO

COo

CO

CO

If} c

CO

CM

O

oo

Q}

oo

COo

CMoo

Ifi CO

CM

CM

COCO > 33

CMCO

'J* o

CO

COo

COo

co

CO>

01

02uo-*-» oc

0) H og

CO

o>

Bu

4?

cu 3 o 2 3

CM

u

OT

a

oo 01

r-l 2 • Pi oe X r-l C c O w >

ii e

?> Ui cu

CD T3C CO 1 q o

TD .-1

0)M ><: 3

to

01 o

00 r-. as .—i

i—i > oo

r—1

II II c

.—!

COc O cu e r-l

undar 3o

cu

*-) t-4 <— o

CD J=

•*-» tn • D. CM

rM e

j= •i—i X oo C c

oo

CO o o E

CD o O LiQ, ^ +1 CN D

Ih

CJ

m o

II <r cu

0] o

x;

.-i CN

S-, •1—1 m o

0) sf !z c toc

oo

O

II II t« >1 O

ned:

"a. a,

•r 1 c

derli •uc

rj

0) H

CO c

01 4-1 C co pq

CJ 'rt on X2 o s 0

Gas

(Fro

118
5

UNITS OF OPTICAL ABSORPTION COEFFICIENTS

The molar (linear) absorption coefficient e is defined by the

Lambert-Beer equation: g = (1/ic) log^ C^ 0 ^t) where I and 1^ are

incident and transmitted intensity, I is the path length, and c is

the concentration . The units for g are (concentration ^ length ^)

.

A variety of equivalent forms of this equation have been used to

define reported values of g. Both logarithmic bases e and 10 have been

used. Length has invariably been expressed in cm. Concentration has

usually been expressed in (mol/liter) . Often a pressure unit has

been used instead of a concentration unit, in which case the temperature

to which the value of the pressure is referred must be specified. When

pressure units are used the absorption coefficient is usually denoted by

-1 -1

k (or a) with units of [(pressure (T)) (length) ]. When the pressure

unit used is (1 atmosphere at 273 K), the value of k is expressed in

-1 -1 -1

any of the numerically equivalent forms: [atm at 273 K cm ]; [ (NTP)

cm ]; or cm \ This last form is equivalent to converting the measured

value of I at T and P to its corresponding value £

q at the reference

state T = 273 K and P = 1 atm (JL = I x (P/P ) x T /T) ) and using

o o

v o

v o o

b

the eqn: k = (III ) log (I /T >. o o t

Alternatively the molecular concentration, n, expressed in (molecules/

3 cm ) may be used. Then the molecular "cross-section", a, is defined as

a = (lAa) log

e

(I 0

/I

t ).

119
6

Because of the diversity of units, when using reported values in

numerical calculations one must always determine what defining equation

was used. When reporting absorption coefficients it is recommended that

the units be given explicitly and that the defining equation appear in

table and figure captions.

A table of conversion factors is attached.

Commission on Symbols, Terminology, and Units, I.U.P.A.C., M. L.

McGlashan chairman, Pure and Applied Chemistry, 21 , 1 (1970).

120
01co

co X

CU

CO

CO XE

T3

CO

CD X o

co

0) CN ON

cuO 4J CO

CO CO i—l X E

CO o

CNIOo

(X) CM

co cuCO 6 co

4-1 XI

CO o

CM

LT5 CN

CO

00

II CN O

CO CUCO E co U XI

CO oo

CO

COoo

i—I

ooON

CN

4-1 CObO cu PC co

CO EE

COo

CN

co£ U

cu

4-1 CO 01CO B co

4-J XI

CO

CN o o

i-i 1—1

V*

X

<r CO CN cu CN o vX 3 • 1—1 —I • r-l CN CN CO>

cu X 4-1 4J c

cu >> •r-l X CJ •H

O 4-1 CN 1—1 m 1 O a. cu • i—( •r-l o CO

J-l CJ o X r-l 1—1 3 3 • CN E o o

CO >X •r-l • r-l 1 4J ;o

CN o CN ml a,

X

CN 1-1 >-i j-i o

CU CO 1—1 CO X a.

CO •H

4J

cu i—l

a x: 3

CTi 4-1 E 1 1

i-l CO o O Ct-4 •\ 1—1 r-l o

4J o CU

X

X cu cu CO CO <l 3 co o o CO a\ i-l CO CO 1-1 O ^X CO CO X • • • • 4-1 7> CN o i—l CN -H r-l 3 0) 1 3 x: E

4J

a

4-1 —I o 4-1 i u ^—N

4J CU CO

01 r>

CO 3 CN O

OJ o 4J

O r-1

<Ta CO CN1 CN CN o o 1 1 4J E O O O E 4-1 i-l i-4 r-l o • CO u N—/ X X X i—l cw • 0) o

CN CN 4-1 4-1 00 oo 3 • • • cu Ml o

oo CO CO , 1 cj 3

•r-l E (U

>4-l 3 QQ

4-1 r-l CO

01

O

X o CJ

If

II , liCJ

J-I

i-HI 3 cu E o eu o *3 CJ

i-H •H 3 r-l cu 4-1 3 1 i—i CU

II

II CO a.

<ai

r-4 i CO o CO u O E CO 1-1 X o E o X CO

i—i CU 1—1

X o CO i i-l CO 1 CO E s—\ 1 CO cu T3 00 n E X 1-1 3 U

r~» » o 3 CO o 3

CN

O i-i i—l

u 4-1 •r4 i-l i 1 cu 4-1 4-1 i-H i—l 1-1 u TD "3

CO CUO o o CU 01 cu ao fiu p> •U CO E co 3 CO CO

4-1

X co CN CN o i-l cu CO B B B u 3 u

-a CJ CJ

X a. o CO X

i—l i-i i—l I-l

H 4J CU

121,
coo

CNI m

CP3 CN

cu 1 o

XI

U

4-1 CU c >>

T3 CO 4J X, C •H o 3 co rH t>0 M-t cu •r-( O

ai 4J Xi i—l

CU o CO C CO •H •H <—1

r-l co CU c ai

CU o

4-1 •H

cu 4J i—< H

a- -a ci— "O Q CO o tM1 co o

CU CO 4-1 co C

co

Q CO i-l (j >H 4J l 4-J cn CO C .-1

Cu o 1 co M CJ a;

cuU i—i Q CJ 3 c 4-J O

i—i

CU

CO p2

r- o C E

CO

O

•H en o 4-1 E

•H c u CJ [ ) n CO H •H cu TD 4-) OS T3 u

co CO

cuM - o

"O

w c • OJ CO co 60 O

CN CO 1 rt « CO g cx cu E 00

oi 00 c cu c H

oo

M •H CU CO bO o co >, r—]

Q_

i—i

t—l 3 o o

i-j 4-1 t4-(

n

r^. oo OJ T3

CM o CU

CNJ 4J °H

TJ I OSOJ ai

0) CUH CJ 3

4J

H ] i c i—i

CO CO co ai co T> pq CU u > T"lw cu

CO s—\•rl

4-1 cu t-l cu CU

CO 00 u-» CO erf S-i u C 1 •H I-l u CO 00 c CU

Cu X. o 4-1 o co c •H CU

OT CU CO 4-) J-l CU u 00 CJ FM

T3 CU CO CO

o; > CU Cu II to o o o ,£3 cu —1

CO ex 4J 3 u <u CO CO o 1-1 •H a, X>

CU CO cu "O < (j 4-1 a* x> c c c CO •H o M 4J t—l OS

cu00 o

CO is Cm o

+i3

cu •H>

CN CU O i-i CO+ rH

CN CT>

T3

i—I O cu CO -H

c*-t O

J3

na

O co + o

+i o

+1 +1

H

HH

OO oo o un m

CN ro i cn

i-i D- a, & i X X X o

cu cu QJ r-i

t-H CN i-H cn 1—1 1—1 00

X

i—1

i—l i—i 1-1 1—1 1—1

O 1 1 i 1 1 1 II

m

O

O o o o o <-t t-l 1—1 1—1 1—1 t—l CO CN X X X X X X tM II m V40 00 00 £>CN cn

CN T-i oooCNoo

OlOcn

CN o 3 3

CN cu o t-i +cu •H +

•H + > >

CU t-l o CU o CO CN i-l £3 S3 U 4J /">» CJ CN CU CN i

r^. t f

CT> •rl t—l c o 3 r-i o co -H CN ^—

g c + u CO C o >H o + CO o + M co

i—l CN e U i—i o •i-l B

cu o •H

w

Q s+ 3

CN 0)

O "H CN >

PC cu

<3- I <^>

r-i

O

CN CT> Pd i-i CJ w + T3 CN O O r-l PC _J

oo

CN o

PC+o

CN A

CN O o o o o

vO o o --1 i—i o o 1 i o o o 0O o o

on oo

00

PC

CJ

CNC

CO •H

•r-l u . CU a E

4J CU

CU

Q

oo

122
o

egi CO

0£ 03 M 05 CO W « o

-aC >.

to 4J •H

CO r-l 00

cu •H o

4-1 XI 1-4 o to •H

1-4cu o3

p. cu E 00

cu c H 2

cuoo o

to z

CM

CU u

COe

•H

4-1 COcu HQo H

4-1 in c i O

—V

co i-i ' O

H

4J 1 CO CO

X r-l

O

C r-4 cu 1 O O 1 vO

CJ CU CM P. i-l

1-1 1-1

X 1 CU 3 1 cu u a o P- 3 .2

1-1

m

00 i—i ai o 1-1 i c E 1 o m o CO o i—i

i-(

•i-t on 1—1 i w e co ><; o o o • II

i-4 co 

m

cu

X peJ CM

O

O

M CM r-4 CM

35CM O

co

33cjA

CM ooCO oo

co ooCO

CO

CTN

CO00 oo

coI oo

CM

X!

4J cu •H n

13 3

•u

,-1 co

CO 5-i u cu •H

•o £

Ra Te

t—i &

cu TD 0 C u cu TJ u

to

w

4-4 c o CO n 1-1 o cu •H >

4J o O

CO ECO

05 + cu CM u 33

14-4 O *— c

i-4 CO

X> cn 33 3 i-i O U

00 +

CM o CT> o CO

•H cn cj M -4 cn

•U 1 U-4 i—i CU i-l o E cn 0 Cn CO m

5-1 r-l cu

j-j

u o o <t

0) ml s i i-4 00 vOo Oj CO vt

03 a* + 3 3

Ma; X!

CM »nC»] CM cu 01 w ml

i-i •H •H CO CO 3 § CJ > > cu B co . CM o

re

0)

nc 33' CU 6

33 co

cu cu o co CM cu 0) x. CM o 3 a o o u "O CM c 1-1 + CO 33 CM CM cu •i-4 T3 cu co cu o + +

co

w «4-l ^5 13 • CU i-4 > S3 5-1 z 01 4-) o\ 4J cu •r-l C E

4-1 cu CM CM 1—1 o 1-4 CJ 5-i S3 CO cu CO 14-4 o o o o o \y 3 ^—

3 Cn T3 cu cu CO U co CM CO -a o o 00 T5 OJ 05 u s 8

33 s

1—1 o 1-4 o c c "O <

CO

u c CJ cou CO

u

Q •1-1 co >>

4J e cu o p- cx

x CO o M-4 •r-4 f

4J 4J s—y o cu

U •1-1 cu t 4-1 f f cu tcu CT» >, 1-4Q

U 4Ju o VO cu r-4 1-1 CU CJ CM o co o o-> > o CO 00 cu

co CO cu c c 1-4 5-1 M-4 5-1 00

CO cu II 53 I-l CO si* CO 33 3 Oi c

CU 05 CJ + •H CM 'ri CO CO cu 0 XI cq T3 cu ••—> CJ CJ cu X! CO fa

CU + 00 CM

u

u +J-4 CO 4-1 •H cu CO c o CU + cu •H 5-1 4-1

5-4 CM co CO E E 5-1 CO CU o Ch S3 cu CO cu CO cu -a cu a CJ Q o a o Q < i

cn cn om o CO

co

603<

123
ERRATA-NB SIR 73-206, second printing

page 13 Reaction Mechanism, 5th line: delete and NO ,,

page 17 Table III:

Heading for columns D, E, F, G, H and I should read:

Absolute rate constants, k/10

^

cm^ molecule '''s ^

page 38 Table I: 1) The values given for e (T ^ 300 K) for \ = 230,

240, 250, 260, and 270 nm are in units of

5 2

10 cm /mol

2) The value of e(T = 1100 K) at \ = 260 nm should be

5 2 1.9 x 10 cm /mol

July 24, 1973

124
FORM NBS-li4A 11-71) U.S. Of- PT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

I. PUBLICATION OR REPORT NO.

NBSIR 73-2 07

2. Gov't Accession No.

4. TIT LE AND SUBTITLE

Chemical Kinetics Data Survey

VI. Photochemical and Rate Data for Twelve Gas Phase

Reactions of Interest for Atmospheric Chemistry

3. Recipient'.- Accession No.

5. Publication Date August 1973

6. Performing Organization Code

7. AUTHOR(S) Robert F. Hampson

8. Performing Organization

. , NBSIR 73-207

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/ \>-ork Lr.it No. 3160409 3160520

11. Contract/Gr.'.nt No.

12. Sponsoring Organization Name and Address

Department of Transportation

Washington, D. C. 20590

National Bureau of Standards

Washington, D. C. 20234

Department of Navy

Naval Ordnance Systems Command

Washington, D. C. 20360

13. Type of Report & Period Covered

Interim

14. Sponsoring Agency Cods

15. SUPPLEMENTARY NOTES

16. ABSTRACT LA 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.) Photochemical and rate data have been evaluated for twelve gas phase

reactions of interest for the chemistry of the stratosphere. The results are presented in data sheets, one for each reaction. For each reaction the data are summarized. A preferred value is given for the rate constant or the. primary

quantum yield and photoabsorption cross section.

17. key words (Alphabetical order, separated by semicolons) Atmospheric chemistry; chemical kinetics;

data evaluation; gas phase reaction; optical absorption cross section; photochemistry;

quantum yield; rate constants.

18. AVAILABILITY STATEMENT

UNLIMITED.

CI FOR OFFICIAL DISTRIBUTION. DO NOT RELEASE

TO NTIS.

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF PAGES

124

22. Price

uscommoc 8C!.:-s-p.-!