jRatfonal Bureau of Standard

NBS T"l

LaVmimical note

474

Critically Evaluated Transition

Probabilities for Ba I and n

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NBS TECHNICAL NOTE 474

ISSUED JANUARY 1969

Critically Evaluated Transition Probabilities

for Ba I and II

B. M. Miles and W. L. Wiese

Atomic Physics Division

Institute for Basic Standards

National Bureau of Standards

Washington, D.C. 20234

NBS Technical Notes are designed to supplement the Bureau's regular publications program. They provide a means for making available scientific data that are of transient or limited interest. Technical Notes may be

listed or referred to in the open literature.

For sale by the Superintendent of Documents, Government Printing Office

Washington, D.C, 20402 - Price 30 cents

Critically Evaluated Transition Probabilities

for Ba I and II

B. M. Miles and W. L. Wiese

Critically evaluated transition probabilities, in order of increasing quantum

numbers } are compiled for Ba I and II from

available literature sources.

Key words: Ba I, Ba II, line strengths,

oscillator strengths, transition probabilities

This special compilation of critically evaluated transition probabilities of Ba I and II has been carried out in response to much recent

interest in the barium spectrum. We have for the arrangement of these

tables adopted the same format as used in our general compilations of

atomic transition probabilities for the first! an(j second ten elements.

Thus we follow in our coding exactly the notation used in the other com- pilations. For convenience, we have collected below the special notation

used in the evaluation of these two spectra.

Special Notation used in the Tables :

1. Multiplet column:

Numbers in parenthesis are the multiplet numbers of

Ref. 3 and 4.

2. Wavelength column:

Wavelengths in brackets are calculated wavelengths

rather than observed ones.

k

Research supported by the Advanced Research Projects Agency of the

Department of Defense under the Strategic Technology Office.
3. Accuracy column:

B - for uncertainties within 10%

C - for uncertainties within 25%

D - for uncertainties wtihin 50%

E - for uncertainties larger than 50%.

4. Literature column:

n - indicates the values have been normalized to a basis

which is different from the one chosen by the author,

is - relative values obtained from LS-coupling tables.

REFERENCES

[1] Wiese, W.L., Smith, M.W. , and Glennon, B.M. , "Atomic Transition

Probabilities-Hydrogen through Neon", NSRDS-NBS 4 Vol. 1 (1966)

(U.S. Government Printing Office, Washington, D.C.).

[2] Wiese, W.L., Smith, M.W. , and Miles, B.M. , "Atomic Transition

Probabilities-Sodium through Calcium", NSRDS-NBS 22 Vol. 2 to be

published (U.S. Government Printing Office, Washington, D.C.).

[3] Moore, C.E., "A Multiplet Table of Astrophysica 1 Interest Revised

Edition," National Bureau of Standards Tech. Note 36 (1959) (U.S.

Government Printing Office, Washington, D.C.).

[4] Moore, C.E., "An Ultraviolet Multiplet Table," National Bureau of

Standards Circular 488, Sec. 3 (1962) (U.S. Government Printing

Office Washington D.C.).
Ground State

Ionization Potential

BARIUM I

Ba I

. 2. 6. ,10_ 2 C 6, 2 1 4s 4p 4d 5s 5p 6s S

5.210 eV = 42032.4 cm"

Allowed Transitions

List of tabulated lines

Wavelength [K] No. Wavelength [A] No. Wavelength [A] No.

2409.98 36 4323.00 44 5971.70 6

2414.83 35 4325.15 40 5997.09 6

2420.85 34 4332.91 44 6019.47 6

2428.17 33 4350.33 38 6063.12 6

2433.28 25 4402.54 41 6110.78 6

2439.55 32 4406.85 40 6341.68 5 2445.38 24 4431.89 38 6450.85 5 2453.12 31 4467.09 39 6482.91 9

2473.20 30 4488.98 44 6498.76 5 2500.2 29 4493.64 44 6527.31 5

2543.2 28 4505.92 38 6595.33 5 2596.64 22 4523.17 38 6675.27 5 2646.50 27 4573.85 38 6693.84 5

2702.63 21 4579.64 41 6865.69 8

2739.24 20 4591.82 13 7059.94 3

2785.28 26 4599.75 37 7120.33 4

3071.58 23 4604.98 13 7195.24 43

3501.11 17 4619.92 45 7280.30 3

3889.33 16 4628.33 13 7392.41 43

3909.91 1 4673.62 13 7417.53 4

3935.72 1 4691.62 38 7488.08 3

3937.87 1 4700.43 45 7672.09 3

3993.40 1 4726.44 14 7780.48 3

3995.66 1 5535.48 19 7905.75 43

4132.43 15 5777.62 42 7911.38 18

4239.56 46 5800.23 42 15000 11

4242.61 40 5805.69 7 27751 12

4264.42 44 5826.30 10 29224 12

4283.10 2 5907.64 6
Aside from the principal resonance line and several other lines of

the resonance series, the oscillator strength situation for Ba I is

quite poor and needs drastic improvement.

The adopted value for the principal resonance line is based on the

lifetime measurements of the 6s6p -"-Pi state by Swagel and Lurio [1] with

the Hanle-effect method (t = 8.37 nsec) and by Hulpke, Paul and Paul [2]

with the phase-shift technique (t = 8.36 nsec). For converting this

number to a transition probability, the small contribution of the

6s5d I-D2 - 6s6p Ip-i transition has to be considered, for which only a rough estimate is available from a Stark effect measurement by Paul (see

Ref. [2]). The "hook measurements" of Prokof'ev [3] as well as Ostrovskii

and Penkin [4] and the semi-empirical calculations by Vainshtein and

Poluektov [5] have been employed for obtaining a relative f -value for the

intercombination line 6s^ 'Sq - 6s6p 3p^. This number should also be

fairly accurate since the three determinations agree within 16 percent.

We have furthermore deduced the f -values for the infrared 6s5d Di o - 6s6p 3p^ transitions from the lifetime measurement of Bucka and Na^el [6]

for the 6s6p 3p^ state by applying the above determined value for the

intercombination line and by using the LS-coupling ratios.

The transitions of the resonance series 6s^ *-S - 6snp -"-P have been

studied by Penkin and Shabanova [7] for the levels n=6 up to n=18 by

employing the "hook" method. The authors find a highly irregular series

behavior which is graphically presented in Figure 1. Most likely, perturbations of the upper states by other neighboring lp states are responsible for this. The accuracy of their results, which are normalized for

the principal resonance line against the above mentioned lifetime, is

estimated to be within 50 percent.

Various other transitions have been studied by Ostrovskii and

Penkin [4] with the "hook" method, and by Eicke [8] with a vortexstabilized arc. Also, Warner [9] has calculated the f-values of a few

ns-mp transitions with the scaled Thomas-Fermi method, accounting for

configuration mixing effects.

Ostrovskii and Penkin's numbers are relative f-values, which we have

normalized against the resonance line using the earlier discussed accurate

lifetime results. Eicke obtains absolute f-values, but they cannot be

directly linked to the resonance line which he has not measured.

The results of the three authors differ greatly, often by factors

of two and much more. We have therefore performed some extensive analyses

to search for causes of the discrepancies. For example, we have plotted

the ratios of Eicke 's f-values against Ostrovskii and Penkin's f-values

as a function of upper and lower energy levels as well as wavelengths.

None of these have revealed any clear systematic trends, however, we noticed that there may be some indication of a systmatic dependence in

Eicke' s values. Namely, his f-values become drastically smaller relative

to the "hook" results for some of the lines involving very high upper

energy levels. In the Ostrovskii and Penkin experiment, on the other

hand, only the populations of the lower energy levels come into play and
100

i i i r i i r

Ba I

c.2 l c n l o 6s S -6snp P, series

10

t

n*

3

f

o.i J I I I I I I I L 7 9

n*—

5

13
for these no apparent trend could be noticed. Furthermore, the greatest

uncertainties in Eicke's method lie in finding the absolute scale while

his relative values should be much more accurate. We find indeed that

a shift of his absolute scale by enlarging all his values by about a factor of two would bring at least half of his f -values into a 50 percent

agreement with Ostrovskii and Penkin's normalized values. We have finally

adopted Ostrovskii and Penkin's data because of the following main reasons:

a) These data may be directly linked up with the precise lifetime results for the resonance line.

b) The "hook" method is a time proven method, which has in

many other instances given reliable results, while the

method used by Eicke has been only applied in two other

experiments,, (However, it must be stated that in at

least one of the other two experiments, which we have

analyzed in detail, Eicke's method gives reliable results.)

c) Uncertainties in the temperature measurement should be some- what less critical for Ostrovskii and Penkin's experiment

than for Eicke's experiment.

d) The few calculated data do not appear to be too trustworthy,

either, since they do not even agree well with experiment on

a relative scale, for which the measurements should be fairly

accurate

.

Since we expect that temperature errors will be quite sensitive

even in the adopted Ostrovskii and Penkin experiment, we estimate the

overall uncertainties not to be much below 50 percent, but even this

figure cannot be considered as too well established because of the

presently existing discrepancies.

References

[1] Swagel, M.W. and Lurio, A ., Phys . Rev. Vo9_, 114-119 (1968).

[2] Hulpke, E., Paul, E. and Paul, W. , Z. Phys ik 177, 257-268 (1964).

[3] Prokof'ev, V.K., Zhur. Eksptl. i. Teoret. Fiz. I, 111-122 (1931).

[4] Ostrovskii, Yu. I. and Penkin, N.P., Optics and Spectroscopy (U.S.S.R.)

9, 371-373 (1960).

[5] Vainshtein, L.A. and Poluektov, I. A., Optics and Spectroscopy

(U.S.S.R.) 12, 254-257 (1962).

[6] Bucka, H. and Nagel, H.H. , Ann. Physik 8, 329-332 (1961).

[7] Penkin, N.P. and Shabanova , L.N. , Optics and Spectroscopy (U.S.S.R.)

L2, 1-5 (1962).

[8] Eicke, H.F., Z. Physik 168, 227-238 (1962).

[9] Warner, B. , Monthly Notices Roy Astron. Soc. 140, 55-59 (1968).
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11
Ground State

Ionization Potential

BARIUM II

Ba II

. 2. 6. ,10,. 2 C 6, 2 n 4s 4p 4d 5s 5p 6s S

10.001 eV = 80686.87 cm

1/2

1

Allowed Transitions

List of tabulated lines:

Wavelength [A] No. Wavelength [A] No. Wavelength [A] No.

1413.3 13 2200.9 25 4934.09 17

1417.2 12 2232.8 24 4997.81 41

1444.7 11 2235.4 24 5185.1 35

1461.3 11 2286.0 25 5361.35 31

1486.6 10 2528.40 22 5391.60 31

1503.9 10 2634.78 22 5413.6 2 1554.3 8 2641.37 22 5421.05 31

1572.7 8 2647.26 23 5428.79 2 1573.9 8 2771.35 23 5480.30 2 1630.4 19 3816.7 33 5784.18 38

1674.4 7 3842.8 33 5853.68 6

1694.3 7 3891.78 20 5981.25 38

169 7.2 7 4024.1 4 5999.85 38

1761.7 9 4057.5 4 6135.83 39

1771.1 9 4130.65 20 6141.72 6

1787.0 9 4166.00 20 6363.2 16

1892.5 28 4287.80 43 6373.2 32

1904.16 5 4325.73 42 6378.91 39

1906.8 29 4329.62 42 6457.7 32

1924.77 5 4405.23 43 6496.90 6

1954.3 28 4470.7 3 7556.8 15

1955.1 28 4509.6 3 7678.3 15

1970.3 29 4524.93 21 8496.8 47

1985.7 26 4554.03 17 8591.4 1 1999.54 18 4616.04 42 8661.9 1

2009.3 27 4708.94 40 8703.7 47

2052.8 26 4843.46 40 8710.82 30

2054.1 26 4847.14 41 8719.1 47

2080.0 27 4850.84 40 8737.74 30

2153.9 24 4899.93 21 8760.6 1

12
Wavelength [A] No. Wavelength [A] No. Wavelength [A] No.

8793.2 48 10768 45 11932 46

8897.5 30 10770 14 12475 37

9031.5 48 10994 14 13058 34

9603.3 36 11089 45 14211 34

10115 36 11127 45 18729 44

10213 36 11519 46 19643 44

10710 14 11577 37 19845 44

The most accurate f -values in this spectrum belong to the lines

having the 6p ^P levels as their upper states. Precise lifetime measurements of these states using the Hanle effect technique have been performed by Bucka et al. [1] and Gallagher [2] } and are in close agreement.

Bucka et al. obtain for the 6p 2p , level a lifetime of 7.0 ± 0.6 nsec,

while Gallagher's result is 6.27 ± 0.25 nsec. We have utilized Gallagher's

data exclusively, since he has also reduced the lifetime data to transition probabilities by measuring the relative strengths of all lines

originating from the 6p 2 P upper levels, i.e., the branching ratios. For

a number of vacuum uv lines and some visible transitions, von Specht [3]

has determined moderately precise f-values - he estimates uncertainties

of 35% - from emission measurements with a wall-stabilized arc operating

in a barium-argon atmosphere. There is unfortunately no direct link

between the data of von Specht and the presumably more accurate lifetime

results of Gallagher. A somewhat indirect comparison via a few low current arc measurements by Kolesnikov and Slepchenko [4] gives the indication that von Specht 's data may be somewhat high. However, Kolesnikov

and Slepchenko's data cannot be considered very reliable since their f-values

disagree quite badly with other results, even on a relative scale.

For many other lines of at least moderate strength we use the recent

calculations by Warner [5], Warner uses essentially the Coulomb approximation by Bates and Damgaard [6] with a modified potential and makes some allowance for configuration mixing and perturbation effects. Since Ba II

is basically a one-electron spectrum this should be a reasonable approach

if the jumping electron has a little interaction with the core. This is

indeed indicated by the few available comparisons with the above mentioned

experiments by Gallagher and von Specht, some of which are presented in

Table I. It is seen that very pronounced differences exist for the 5d-6p

transitions, which is clearly non-Coulombic . The agreement becomes then

increasingly better as the jumping electron gets further away from the

core, and is already quite acceptable for the 6s-6p transition. Some

isolated cancellation seems to be apparent as indicated for example by

the rather small theoretical gf-value for the 6s-8p transition. We have

therefore limited our tabulation of Warner's f-values to those transitions

which are either in the visible or near infrared (\ smaller than 20,000 A)

and which have gf -values larger than 10"^.

13
Table I. Comparison of some Ba II f-values calculated by Warner on the

basis of the Coulomb-approximation with experimental results

by Gallagher (Hanle-ef f ect) and von Specht (stabilized arc).

Transition \ Warner [5] Gallagher [2] v. Specht [3]

5d

2 D

5/2

- 6p F3/2

6141.72 0.12 0.14 - 2^D

3/2

- V\3/2 5853.68 0.017 0.025 -

2^

D

3/2

" *l/2

6496.90 0.087 0.105 -

5d

2 D

3/2

- 8p F

3/2

1761.7 1.12xl0"

4

- 1.8xl0"

4

2^

D

3/2

" r l/2

1771.1 0.93xl0"4

- 7.9xl0"

4

2^

D

5/2

- F3/2

1787.0 0.035xl0" 3

- 1.4xl0" 3

5d

2 D

3/2

- 6f

2 F

o5/2

1674.4 0.38xl0" 6

- 1.4xl0"

2

2 °5/2

" F

7/2

1694.3 0.096xl0"

2

- 1.2xl0"

2

2 D

5/2

" F

5/2

1697.2 0.26xl0'

4

- 7.3xl0"

4

5d

2 D

3/2

- 7f F

5/2

1554.3 0.45xl0"

2

- 1.4xl0"

2

2^

°5/2

" F

7/2

1572.7 0.22xl0'

2

- 1.2xl0"

2

2^

D

5/2

" F

5/2

1573.9 2.95xl0"4

- 5.8xl0" 4

6s

2

S 1/2

- 6p ^3/2 4554.03 0.78 0.74

2 sh

l/2 *l/2

4934.09 0.37 0.35 -

6s

2 S 1/2

- 8p r l/2

1630.4 0.018xl0"4

- 6.6xl0'4

6P

2 P

3/2

- 6d 2^

D

5/2

4130.65 0.898 - 1.2

V - *3/2

2^

D

3/2

4166.00 0.103 - 0.095

6 P

2 P°

/2

- 7s

2 Sb l/2

4524.93 0.145 - 0.22

iU
References

[1] Bucka, H., Eichler, J. and Oppen, G., Z. Naturforsch. 21a , 654-656

(1966).

[2] Gallagher, A., Phys . Rev. 157. 24-30 (1967).

[3] von Specht, J. } Max-Planck-Institut . fur Physik und Astrophysik,

MPI-PAE 4/68 (1968).

[4] Kolesnikov, N.S. and Slepchenko, N.S., Fiz. Probl. Spektroskopii,

Akad, Nauk. S.S.S.R., Materialy 13-Go (Trinadtsatogo) Soveshch.,

Leningrad 41-43 (1962).

[5] Warner, B. , Monthly Notices Roy. Astron. Soc . L39, 115-128 (1968).

[6] Bates, D.R. and Damgaard, A., Phil. Trans. Roy. Soc. London, Ser.

A 242, 101-122 (1949).

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22
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