bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermalization in Infrared Multiple Photon Induced Reactions. The PressureDependence of the Trans → Cis Isomerization of Crotonitrile
Authors: Guckert Joseph R. , Carr Robert W.
Published: September 2007

The infrared multiple photon trans → cis isomerization of crotonitrile was studied over the pressure
range 0.02 torr to 10 torr at fluences of approximately 4J/cm2 using collimated TEA CO2 laser radiation at
942 cm-1. Only minor quantifies of fragmentation products were found at these conditions. At pressures
of 0.1 torr or less, the trans form was completely converted to cis form by about 5000 laser pulses. On
increasing the pressure a collisional regime was entered in which photostationary states were reached with
fewer pulses and having smaller conversions than at low pressure. Both the number of pulses and the
conversion decreased monotonically with increasing pressure. The tactic of driving the reaction in the
exothermic direction gave evidence that the reaction does not occur solely by thermal isomedzation even
in the highly eollisional 10 torr experiments, but that it still has a nonthermal component due to laser
induced isomerization.
The Role of Molecular Complexes in a Hollow‐Cathode CW HeCd+ Laser
Authors: Telle H. H. , Morgan C. Grey , Acosta-Ortiz S. E. , Karyono
Published: September 2007

The importance of molecular complexes in gas discharge lasers has long been recognised, and indeed they
are the essence in excimer lasers. For other discharge lasers operating with gas mixtures, for example
metal vapour lasers, the role of molecular complexes in the laser discharge has hardly been addressed. In
this work the emission from a cw multi‐colour hollow‐cathode HeCd+ laser has been investigated
spectroscopically, and emphasis was placed on the detection of molecular bands. Specifically the presence
of in the laser discharge was confirmed which is thought to play a major role in the generation of
the green laser lines. Emission bands attributed to the metal dimer were identified; however, this
dimer does not seem to be of importance in the laser process. In addition to the and emission
strong molecular continuum bands, exhibiting gain, were observed which accompany all laser lines; these
can only be interpreted as originating from transitions in the ionic complex (HeCd+)*.
The Potential of Vacuum Ultraviolet Photoionization MassSpectrometry in Monitoring Photofragmentation of Organometallics
Authors: Georgiou S. , Mastoraki E. , Raptakis E. , Xenidi Z.
Published: September 2007

The paper examines the potential of vacuum ultraviolet (VUV) photoionization mass spectroscopy in
probing the fragmentation of organometallics in molecular‐beam studies and laser‐assisted deposition
processes. To this end, the ionic fragmentation pattern of few common organometallics, namely metallocenes
and carbonyls, is examined at selected VUV wavelengths, produced by microwave‐discharge
resonance atomic lamps. Discussion of the recorded spectra in terms of the electronic structure of the
compounds indicates lack of dynamical bias in the VUV photoionization/fragmentation of metal complexes.
Excitation with VUV light results in simpler ionic fragmentation patterns than what observed
with electron‐impact ionization, thereby enabling accurate monitoring of the excimer‐laser photodissociation
of organometallics. Finally, the intensity of the VUV ionic signal appears to be adequate
for molecular‐beam studies. An illustrative example is provided for the study of the 248nm‐induced
photodesorption of Mo(CO)6 from cryogenic films.
Characterization of New Excimer Pumped UV Laser Dyes 3.P‐Quinqui‐, Sexi‐, Octi‐ and Deciphenyls
Authors: Seliskar C. J. , Landis D. A. , Kauffman J. M. , Aziz M. A. , Steppel R. N. , Kelley C. J. , Qin Yuanxi , Ghiorghis A.
Published: September 2007

The spectroscopic and lasing characteristics of a series of 308 nm pumped p‐oligophenylenes with five or
more phenyl rings have been studied. Quantitative comparisons of the absorption spectra of these dyes
with numerous other dyes in this class of compounds can be made by defining a parameter, theta, as the
sum of the number of phenyl rings and the number of ring‐bridges. Statistically good linear regressions
result from the correlations of molar extinction with theta and from wavelength of absorbance with the
reciprocal of theta. We find that these correlations provide good predictive information in deciding which
dyes to attempt to synthesize for testing. The lasing characteristics of the dyes studied show that these
dyes are amongst the best dyes in this class of dyes. Some of these dyes have exceptionally long lifetimes
coupled with acceptable conversion efficiencies.
Laser Induced Fluorescence From CF2 Excited at 248 Nm
Authors: Wlnkelmann G. , Kuhls R. , Osmanow R. , Linke E.
Published: September 2007

KrF–laser‐induced fluorescence from CF2‐radicals was investigated during photolysis of CF2Cl2 and
CF2HCl by 193 nm laserlight. In contrast to other publications, which postulated single‐vibronic‐level fluorescence, the fluorescence is caused by excitation from four closely situated absorption bands. These fluorescence bands of four series, are assigned to Ã1B1
− 1A1
transitions with Δv1 = 0 and 0 ≤ ≤ 30. The Franck – Condon factors of the Ã1B1 (0, 6, 0) –1A1 (0, , 0) transitions,
the frequencies of the bending vibration (

=673± 2cm–1) and the anharmonicity constants
= –0.94 ± 0.08 cm-1 and
= –0.44 ± 0.10 cm–1 were more precisely determined. For the first
time higher anharmonicity constants are evaluated with + = –3.5 ± 1.0 cm–1 and
= –0.05 ± 0.02 cm–1.
Silicon Atoms as Intermediates in the Nonlinear Photochemistry ofSi(CH3)4–nCln(n = 0, 1, 2, 3, 4) Compounds
Authors: Mualem Orly , Gedanken Aharon
Published: September 2007

The resonance enhanced multiphoton ionization (REMPI) of Si (CH3)4–nCln compounds (with n = 0, 1, 2, 3, 4) was measured in the 400–360 nm range. The resonances observed were attributed to a
silicon atom formed in the 1D2 excited state. This indicates that the first step in the photochemical process
is the dissociation of the molecule which is followed by the ionization of the silicon atom.
IR Laser Chemistry of Dimethylnitramine and Diethylnitramine
Authors: Lazarou Yannis G. , Papagiannakopoulos Panos
Published: September 2007

The infrared multiphoton decomposition of dimethylnitramine and diethylnitramine in the gas phase
under almost collisionless conditions has been studied with a tunable CO2 laser. The steady state rate
coefficient for their unimolecular decomposition were found to be kDENA(st) = 105.5 ± 0.1(I/MW cm–2) s–1,
and kDENA(st) = 105.2 ± 0.1(I/MW cm–2) s–1, for laser intensities in the range 3–15 MW cm –2. The dependence
of rate constants and product yields on laser fluence have indicated that the unimolecular dissociation
of both nitramines occurs via scission of the N‐NO2 bond, and the main secondary reaction leading to
the final photolysis products (nitrosamine and nitroxide) is the oxidation reaction of nascent dialkylamino
radical with parent nitramine or NO2 product.
Excimer Laser Used as a Materials Characterization Tool: SulphideInclusion Printing in Steel
Authors: Mcintosh J. , Zervaki A. , Papadimitriou K. , Haidemenopoulos G. N. , Manousaki A. , Zergioti G. , Hontzopoulos E.
Published: September 2007

An application of the excimer laser in the area of material characterization making use of its ablative
ability to perform surface sulphur printing is presented. It is shown that the differential ablative and
surface melting capability of the excimer laser is useful in microetching sulphide inclusions in flat
polished steel samples and rough fracture surfaces.
An optimum laser fluence is found to be that which melts the sulphide particles without significant
melting of the steel matrix or causing overlap of the characteristic halo formed by the out‐flowing liquid
from the sulphides.
The geometric similarity of the sulphide inclusions is maintained and its spatial extent is amplified
about 10 times. This brings sub‐micron sulphide particles into optical resolution range.
The liquid wetting behavior of the sulphide liquid is variable with Mn/Fe ratio and determines the
extent of the halo formation.
Zero‐ and Nonzero‐Nuclear‐Spin Isotope Response in ResonantlyEnhanced Multiphoton Ionization of Kr nd Xe With Broad BandLasers
Authors: Charalambidis D. , Shao Y. L. , Moustaizis S. D. , Fotakis C.
Published: September 2007

The abundance of the 83Kr isotope, determined by ion mass analysis following three photon resonant
four photon ionization via the 5s’ [1/2]1 state with a broadband laser is found to differ from the expected
natural value. This effect is discussed in terms of a change of the ionization response due to the decay
of coherence in the intermediate state to its hyperfine structure coupling. The nonzero nuclear spin
isotopes of Xe have not shown any effect of this type in three different ionization schemes under the
present experimental conditions.
IR‐Laser Induced Branch Chain Reaction of Hypofluorites WithHydrogen
Authors: Aslanidi E. B. , Zainulin R. I. , Kalandadze N. K. , Turischev J. S.
Published: September 2007

The parameters of chain explosion occurrence in the mixture of CF3OF or CF2(OF)2 with hydrogen
induced by a pulsed CO2‐laser were studied experimentally. The ranges of inflammation for the both cases
were obtained. IR‐fluorescence spectra associated with the chain explosion were studied. The chemical
reactions describing the observed process qualitatively are given assuming the chain energy branching.
Channels of Product Formation and Excited Molecules Relaxation atMultiphoton Dissociation of Chlorodifluoromethane
Authors: Dimand V. A. , Maltzev K. K. , Nadeikin A. A. , Nikitin A. I. , Velichko A. M. , Vnukov A. V.
Published: September 2007

C2F4, molecules have been for the first time directly proved to be generated in the reaction of
vibrationally‐excited molecules CF2HCl. The contribution of this reaction to CF2HCl multiphoton
dissociation (MPD) products formation was shown to become predominant at the initial CF2HCl pressures
about ten Torr. Also fast relaxation of the highly excited molecules CF2HCl on the product molecules
C2F4 was discovered.
Evolution of the Spectroscopic Properties of Hg and Hg2 Interacting with Molecular Clusters
Authors: Dedonder-Lardeux C. , Martrenchard-Barra S. , Jouvet C. , Solgadi D. , Amar F.
Published: September 2007

The spectroscopic properties of mercury and mercury dimer clustered with water, ammonia and 1–1
dimethylether have been studied through mass selected resonance enhanced multiphoton ionization
spectroscopy. The ground state structure of these clusters have been calculated. Comparison between
calculations and experimental results show that the spectrum is not governed by the structural properties
of the clusters.
Stimulated‐Emission‐Pumping Laser‐Induced‐Fluorescence Spectroscopy of Phenol and Anisole
Authors: Takayanagi Masao , Hanazaki Ichiro
Published: September 2007

The SEP–LIF (stimulated emission pumping‐laser induced fluorescence) technique was applied to the
investigation of dynamical behavior of vibrationally excited phenol and anisole produced in the supersonic
expansion. In the SEP–LIF scheme, a molecule excited to a specific vibrational state by SEP is detected
by measuring the LIF excitation spectrum with an appropriate delay to probe the vibrational relaxation.
Four vibrational states, 6a1, 16a2, 121 and 11, of phenol, and six vibrational states, 18b1, 18b2, 6a1, 121,
16a2 and 11, of anisole were investigated. For both of phenol and anisole, it is found that the relaxation
of the vibrational states below 1,000 cm-1 in the ground electronic state is so slow under the collisionless
condition that only the transitions from the vibrational states initially prepared by SEP are observed as
the SEP‐induced bands in the SEP–LIF spectra. The low frequency torsional motion of methyl group in
anisole does not accelerate IVR (intramolecular vibrational redistribution) much in this energy region.
Threshold Ionization Spectroscopy of the Low Frequency Vibrational Modes of Styrene and Trans‐Stilbene Cations
Authors: Smith Jonathan M. , Knee J. L.
Published: September 2007

High resolution photoelectron spectra are reported for styrene and stilbene with an emphasis on identifying
the low frequency modes which are important in the phenyl–vinyl torsional motion. In the styrene
cation three low frequency out‐of‐plane vibrations are measured, ν42, ν41 and ν40 as well as a number
of higher frequency in plane modes. Generally the low frequency modes do not appear with significant
intensity but by pumping the appropriate modes in the S1 intermediate state the intensity for these modes
in the threshold ionization spectrum is quite good. In the stilbene cation the analogous phenyl–vinyl
torsion, ν37, is also measured as well as the related mode ν36. The ethylene torsional mode in stilbene
is not observed. In both molecules the observed frequencies are used to relate the electronic structure
of the cation to the S1 and S0 states of the molecule.
Matrix Isolation Study of the 193 nm Excimer Laser Photochemistry of Hexafluorobenzene
Authors: Laboy Jorge L. , Ault Bruce S.
Published: September 2007

193 nm excimer laser irradiation of Ar/C6F6 samples during deposition onto a cryogenic surface has led to the formation and isolation of a range of products, the dominant being hexafluoro‐Dewar benzene. Additional absorptions likely due to the previously unreported hexafluorobenzvalene were observed, along with extensive fragmentation and additional minor products. When either Cl2 or CCl4 was doped into the Ar/C6F6 sample as an electron trap, a number of additional product bands were noted. A few of these were destroyed by subsequent Hg arc irradiation, and at least one is tentatively assigned to the C6F6+ cation. A comparison to previous studies of the photochemistry of C6F6 is made.
The Vibrational‐Translational Relaxation of CF2HCl in Argon
Authors: Tosa V. , Bruzzese R. , de Lisio C. , Tescione D.
Published: September 2007

We report in this paper results concerning the vibrational‐translational (VT) rates of CF2HCl diluted in Ar as a neutral buffer. The dependence on the buffer concentration and on the initial vibrational energy distribution are obtained by using the 9R(48) and the 9R(34) CO2 laser lines for the excitation process. The differences observed between the results corresponding to the two lines bear valuable information about the dependence of the VT relaxation process on the specific initial conditions of vibrational excitation.
A Bottleneck Effect in Perfluoropropene
Authors: Torresano J. A. , Santos M. , González-Díaz P. F.
Published: September 2007

By investigating the infrared dissociation yield of perfluoropropene under a convenient range of experimental
conditions on pressure, laser fluence and number of irradiation shots, we have seen that i)
besides the already known final products, C2F4 and C2F6, the dissociation of this molecule also produces
polytetrafluoroethylene, and ii) contrary to what one should expect from its rather large molecular size,
perfluoropropene opposes a strong bottleneck effect against absorption of resonant infrared radiation, at
least for irradiation fluences smaller than ≈ 1.8 Jcm-2
Vibrational Relaxation of the 2v5 Overtone of CDCl3 Highly Excited by a Tea CO2 Laser
Authors: Vazquez M. A. , AzcáRate M. L. , Quel E. J. , Doyennette L. , Rinaldi C. , Ferrero J. C. , (Citefa-Conicet) Ceilap
Published: September 2007

A homemade TEA CO2 laser tuned to the 1OP(48) line, 10.91 μm, was used to excite the v4
mode of CDCl3 (914 cm-1). The IR fluorescence signal from the CDCl32v5
overtone band (1492 cm-1) was isolated by means of a gaseous filter. The temporal variation of this fluorescence emission was studied as a function of the laser fluence. Under high excitation conditions, non‐linear effects become obvious, and measured rate constants greater than predicted from linear kinetic rate equations have been found.
The Spectroscopy and Photophysics of π Hydrogen‐BondedComplexes: Benzene–CHCl3
Authors: Gotch Albert J. , Pribble R. Nathan , Ensminger Frederick A. , Zwier Timothy S.
Published: September 2007

A vibronic level study of the spectroscopy and photophysics of the C6H6–CHCl3 complex has been
carried out using a combination of laser‐induced fluorescence and resonant two‐photon ionization (R2PI).
In C6H6‐CHCl3, the S1–S0 origin remains forbidden while the 1610 transition is weakly induced. Neither
610 nor 1610 are split by the presence of the CHCl3 molecule. On this basis, a C3vstructure is deduced
for the complex, placing CHCl3 on the six‐fold axis of benzene. The large blue‐shift of the complex’s
absorption relative to benzene (+178 cm–1) and the efficient fragmentation of the complex following
one‐color R2PI reflect a hydrogen‐bonded orientation for CHCl3 relative to benzene’ π
cloud. Dispersed
fluorescence scans place a firm upper bound on the ground state binding energy of the complex of
2,024 cm–1. Both the 61and 61 11 levels do not dissociate on the time‐scale of the S1 fluorescence and
show evidence of extensive state mixing with van der Waals’ levels primarily built on the 00 level of
benzene. The C6H6–(CHCl3)2 cluster shows extensive intermolecular structure beginning at +84 cm–1, a
strong origin transition, and splitting of 61. A structure which places both CHCl3 molecules on the same
side of the benzene ring is suggested on this basis. The vibronic level scheme used to deduce the structure
of C6H6–CHCl3 is tested against previous data on other C6H6–X complexes. The scheme is found to be
capable, in favorable cases, of deducing the structures of C6H6–X complexes based purely on vibronic
level data. Finally, the results on C6H6–CHCl3 are compared with those on C6H6–HCl and C6H6‐H2O to evaluate the characteristics of the n hydrogen bond.
The Origin of SO2 Afterglows as Revealed by Magnetic Field Effects
Authors: Abe Haruo
Published: September 2007

The chemiluminescence intensity in the low pressure diffusion flame of the CS2 + O/N2 system was
found to be considerably affected by external magnetic fields. The emitter in the flame was identified
as the main emitter in the SO2 afterglow. The measurements of the field strength dependence, collisional
effect, and spectral distribution of the magnetic field effect revealed the major emitter as the SO2 in the
state. External magnetic fields were also found to quench fluorescence remarkably emitted from the
vibronic levels just below the predissociation threshold in the
state. From the observed vibrational‐level,
field‐strength, and pressure dependences of the magnetic quenching, it became evident that the major
emitter of chemiluminescence in the flame could be assigned to the SO2 molecule in the vibronic levels
located at about 800 cm–1 below the predissociation threshold in the
state
Stimulated Raman–UV Optical Double Resonance Spectroscopy of Van Der Waals Complexes of Benzene
Authors: Ebata Takayuki , Ishikawa Seiichi , Ito Mitsuo , Hyodo Shi-Aki
Published: September 2007

Spectroscopic and dynamical studies of the van der Waals complexes of benzene–Ar, benzene–N2 and benzene dimer in the electronically ground state (S0) have been performed by the use of stimulated Raman–UV optical double resonance spectroscopy. The vibrational frequency of mode 1 of the complexes and the decay rate constants of the 11 levels (∼993 cm-1) have been measured. The vibrational frequency
shifts of mode 1 in S0 upon complex formation were less than 1 cm-1for all the complexes. On the
other hand, the decay rate constant due to intramolecular vibrational redistribution and/or vibrational
predissociation showed a drastic change. The decay rate constant of the 11 level of the benzene dimer
was 2.4 × 107 s-1, while those of the benzene–Ar and benzene–N2 complexes were much smaller than 1 × 106 s-1. It was also found that the decay rate constant in S0 is much smaller than that in S1. For the
benzene dimer, the depolarization ratio of Raman band of mode 1 was recalculated by taking into account
of the anisotropy of the polarizability of benzene molecule. The comparison between the observed and
calculated polarization ratio shows that the benzene dimer has the “T‐shaped” structure which was
proposed by the group of Felker.
Optical–Optical Double Resonance Spectroscopy of NO2 in the 590.1 nm Region
Authors: Shibuya Kazuhiko , Kusumoto Tadasi , Nagai Hidekazu
Published: September 2007

Optical–optical double resonance (OODR) spectroscopy has been applied to the rotational and vibronic
analysis of the thirty nine eigenstates of NO2 existing in the energy region of 16,980–17,124 cm-1 above the ground state. These excited states are concluded to be the mixed states of NO2 generated by spin‐orbit
and/or orbital‐rotation interaction between the B2 and A1 vibronic levels. The mixing mechanism of the
excited states is discussed in terms of available information on the visible excited states of NO2.
Singlet And Triplet n,π∗ Transitions of Jet‐Cooled p‐Benzoquinone
Authors: Suzuka Isamu , Sanekata Masaomi , Ito Mitsuo , Ohta Nobuhiro
Published: September 2007

The fluorescence/phosphorescence excitation spectra, the dispersed fluorescence/phosphorescence spectra
and the sensitized phosphorescence excitation spectrum have been measured for jet‐cooled p‐benzoquinone.
The assignments of vibronic bands in the 1B1g(n-,π∗) ← 1Ag and 1Au(n+,π∗) ← 1Ag transitions
have been definitely established. The phosphorescence spectra from vibronic levels of 3Au exhibit a
feature of single vibronic level emission. The 3Au ← 1Ag transition was also vibrationally analyzed.
Radiative Lifetimes and Collision Processes in Sodium‐Rare Gas and Sodium‐Hydrogen Systems
Authors: Vassie L. H. , Telle H. H.
Published: September 2007

Investigations of the collisional interactions between sodium atoms in the 32P states and helium and hydrogen gases are described. Studies of collision‐induced mixing and quenching interactions have been carried out under conditions where chemical reaction to produce sodium hydride is possible. Thus the sodium number derivatives are sufficient for radiation trapping to occur. This is in contrast to virtually all previous investigations in which conditions were such that this effect need not be considered. The intensity and temporal behaviour of laser induced fluorescence (LIF) resulting from the photoexcitation of the sodium 32P states is monitored as a function of foreign gas pressure. Whilst many of the features observed are to be expected, results show how radiation trapping strongly influences cross‐section determination. The need for a more rigorous treatment of collision cross‐sections under these conditions, which are often more realistic than the ‘ideal’ trapping free situations, is demonstrated.
IR‐UV Double Resonance Spectrum of Acetylene Below and Above the Predissociation Threshold
Authors: Fujii Masaaki , Tanabe Shigeki , Okuzawa Yasuo , Ito Mitsuo
Published: September 2007

The Ã1Au ←
electronic transition of the vibrationally excited acetylene molecule was studied by
IR–UV double resonance spectroscopy in gas and in a supersonic jet. The C–H antisymmetric stretching
vibration νCHant in the Ã state was clearly observed when the molecule was excited to the νCHsym + νCHant
combination vibration in the state by the IR laser. When the νCHant fundamental vibration was excited,
the C–H in‐plane cis‐bending vibration νcis(in) in the Ã state was observed strongly, while νCHant almost
disappeared. The difference was interpreted in terms of Fermi resonance of the νCHant fundamental vibration
in . The predissociation threshold was newly determined to be 46,439˼46,673 cm-1 (133.11 ± 0.33 kcal/mol). In the region above the predissociation threshold, strong vibrational mixing was found. The
higher members of the progression of the trans‐bending vibration starting from νCHant were assigned. It
was suggested that the nonradiative relaxation accelerated in the region above 51,744 cm-1.
Pulsed‐Laser Induced Chain Addition Reaction of Butanal to Diethyl Maleate
Authors: Stringat R. , Fabre G. , Alessandri M. , Fellous R.
Published: September 2007

By irradiation of a 5/1 mixture of butanal and diethyl maleate with a pulsed Nd‐YAG laser (10 Hz, 13 ns), frequency tripled (λ = 355 nm), diethyl butanoyl succinate is formed by addition. The quantum yield is greater than 1 which means that a chain mechanism occurs which was not the case in previous studies with a mercury lamp. The quantum yield is a function of light intensity and can reach 280 in the range explored (I = 3020 to I = 0.303 KW.cm-2). The excited aldehyde produces the two radicals nPr‐ĊHOH and nPr—ĊO. The nucleophilic acyl radical reacts on the diethyl maleate to form an intermediary radical which givs the adduct and a new acyl radical in the presence of an aldehyde molecule. The second radical nPr—ĊHOH captures a hydrogen from the aldehyde producing another acyl radical and butanol.
Molecular Dynamics in Solution Probed by the Transient GratingMethod With a Nanosecond Pulsed Laser
Authors: Terazima Masahide , Okamoto Koichi , Hirota Noboru
Published: September 2007

Molecular dynamics in organic solution is investigated by the transient grating method with a nanosecond
pulsed laser and a fast detection system. First, the dynamics of methyl red (MR) is studied for the probe
of the translational diffusion process of solution. The origin of the TG signal which represents the mass
diffusion is attributed to the phase grating created by the different refractive indices of the cis and trans
forms. The cis form of MR, which has a slightly smaller molecular volume than the trans form is found
to diffuse more slowly in alcoholic and aldehyde solutions. The measured diffusion coefficients (D) are
compared with theoretically calculated values. Second, the TG method is applied to elucidate the
dynamics of transient radicals created by photochemical reactions. The determined D of the radicals are
about 3∼4 times smaller than those of the parent non‐radical molecules even though the molecular
volumes are similar to each other. The advantages as well as the disadvantages of the TG method for
elucidating the solvent dynamics are discussed.
Dynamics of the Reaction S(1D) + HD, H2, and D2: Isotopic Branching Ratios and Translational Energy Release
Authors: Inagaki Yousuke , Shamsuddin Sayed Mohammed , Matsumi Yutaka , Kawasaki Masahiro
Published: September 2007

Doppler profiles of H and D atoms from the reaction S(1D) with HD and a 1:1 mixture of H2 and D2
have been measured by a laser‐induced fluorescence technique with a vacuum ultraviolet laser. An
isotopic channel branching ratio of φ (SD + H)/φ (SH + D) is measured to be 0.9 ± 0.1 in the reaction
of S(1D) + HD at average collision energy Ecoll = 1.2 kcal/mol. In S(1D) + HD, D2, and H2, the translational
energies released are almost the same, 4.6 ± 0.5 kcal/mol for H and D production channels. The measured
branching ratio and translational energy release suggest that the reaction proceeds via a long‐lived complex
formed by insertion.
Fluorescence Property and its Magnetic Field Dependence Across thePhotodissociation Threshold of CH3CHO and CD3CDO in a SupersonicJet
Authors: Ohta Nobuhiro
Published: September 2007

Fluorescence characteristics of jet‐cooled acetaldehyde at zero field is confirmed to change from the
small molecule behavior to the statistical limit behavior in CH3CHO and to the intermediate case in
CD3CDO, as the excitation energy increases across the dissociation threshold located below 320 nm. The
excitation energy dependence both of the intensity and of the lifetime of the slow fluorescence shows
that the dissociation rate becomes faster abruptly with increasing excess energy above the threshold, and
the excess energy dependence above the threshold seems to be more drastic in CH3CHO than in CD3CDO.
External magnetic field as well as the dissociation in the triplet state plays a role to increase the level
density of the triplet state coupled to S1. On excitation below the dissociation threshold, the magnetic
quenching of fluorescence becomes more efficient with increasing excess energy and the efficiency of
the quenching is larger in CD3CDO than that in CH3CHO by a factor of about 2. On excitation above
the threshold, however, the efficiency becomes lower with increasing excitation energy. Thus, the magnetic
field effects on fluorescence also change drastically across the dissociation threshold.
Comment: “Dynamics of the B and a  3Π(1u) States of Chlorine by Laser Induced Fluorescence”
Authors: Billy N. , Gouédard G. , Girard B. , Vigué J.
Published: September 2007

The paper by Martinez et al.1 describes their study of the decay of the Cl2 B state by radiative and
predissociation processes. The results of this work and the conclusions of their analysis are in strong
disagreement with our results.2,3 We want to clarify these uncertainties in the present comment.
Photoionization of Excimers Produced in Naphthalene Clusters
Authors: Saigusa Hiroyuki
Published: September 2007

The excited‐state dynamics of small naphthalene clusters that occur upon selective excitation into S1
vibronic levels have been investigated by mass‐selective pump‐probe photoionization spectroscopy. The
results provide direct evidence for structural isomerization of the initially excited van der Waals cluster
into an excimer geometry, consistent with the fluorescence results. The excimer has been identified as
a cluster having a strongly bound dimer core surrounded by ground‐state molecules, thus ruling out the
possibility of excimer formation via monomer evaporation. We have also found that ionization is enhanced
when the initially excited cluster undergoes excimer formation, which provides a new ionization
mechanism for aromatic clusters. The ionization enhancement is explained by the Franck–Condon factors
associated with the ionizing transition from the excimer state.
Photodissociation Dynamics of Cluster Ions
Authors: Nagata Takashi
Published: September 2007

The time‐of‐flight (TOF) spectra of Ar+ and Ar fragments produced in the photodissociation of (3 ≦ n ≧ 24) were measured at wavelength around 540 nm. The kinetic‐energy and angular distributions
of the neutral photofragments were obtained for n = 3, 9 and 24 by a simulation analysis of the measured
TOF spectral profiles. The overall aspect of the photodissociation process of is deduced from these
distributions within the context of trimer ion core model; a linear core is solvated by neutral Ar
atoms. For with 4 ≦ n ≲ 14, direct dissociation of the chromophoric core gives rise to Ar+
and/or Ar fragments with a high kinetic energy release. For the larger (n ≳ 14), the production of
high‐kinetic‐energy fragments is suppressed; “evaporation” of the solvent Ar atoms is instead the
dominant channel of photofragmentation.
Sub‐Doppler High‐Resolution Spectroscopy of 15V Band of CS2 and the Zeeman Effect
Authors: Doi Atsushi , Ohtsuka Masaya , Nishizawa Kiyoshi , Baba Masaaki , Katô Hajime
Published: September 2007

Excitation spectra and the Zeeman spectra of CS2 in the region of 31320‐31445 cm-1were measured with sub‐Doppler resolution. Observed rotational lines were classified to 14 series of lines (vibronic bands) and were named by the wavenumbers of their band origins. The 31344.9 band is the strongest one and is assigned as the main band of the V1B20v20(K = 0) – X1
0000 transition. Most of the extra bands may be allowed by the vibronic interaction between the V1B20v20(K = 0) level and singlet levels, which are mostly high vibrational levels of the 1A1(X1) state. The Zeeman splittings are observed for several lines in almost all bands. These may be originating from the spin‐orbit interaction between the rotational levels, which have accidentally nearly the same energy, of the 1A1(X1) state and the 3A2
(3Δu
) or/and 3B2
(3Δu) state.
Intermolecular Vibrations of the Complex of NO in the nsσ Rydberg States and Ar
Authors: Tsuji Kazuhide , Shibuya Kazuhiko , Obi Kinichi
Published: September 2007

The resonance enhanced multiphoton ionization method has been applied to the study of NO‐Ar van der Waals complex in the nsσ (n = 3,4) Rydberg states. We have assigned the intermolecular vibrations appearing in the Ã— excitation spectrum of the complex. The bending structure appeared only with the excitation of the stretching mode in the Ã state, which was interpreted by intermolecular forces. The ‐Ã excitation spectra were independent of the initial intermolecular level in the Ã state and the dissociation threshold to NO(E2∑+
) + Ar was determined to be 60950 cm-1. The s–d mixing in the 4sσ orbital would make the intermolecular vibrational structure in the —Ãspectra complex.
Collision Energy Dependence of the Overall Rate Constant for the Reaction NH(a1Δ) + HN3
Authors: Watanabe Akihiro , Yamasaki Katsuyoshi , Tokue Ikuo
Published: September 2007

The overall rate constant for the reaction NH(a1Δ
) + HN3 has been determined by the laser photolysis of hydrogen azide (HN3) at 266 nm and 193nm. The visible emission from vibronically excited NH2(2A1) was dispersed and its time‐dependent profiles were measured at several wavelengths. The rate constants are dependent not only on the photolysis wavelengths but also on the vibrational levels of the NH2(2A1) produced in the reaction. The intermolecular potential between NH(a1Δ)
and HN3 was determined to be the form V(R) = –C/Rs (2 < s < 4, C: constant) from the analysis with a long‐range potential approximation. The interaction between NH(a1Δ
) and HN3 is mainly governed by the dipoledipole interaction in the initial stage of the reaction.
The Importance of Electron Transfer Mechanism in Reactions of Neutral Transition Metal Atoms
Authors: Honma Kenji , Clemmer David E.
Published: September 2007

Reaction kinetics of ground, Ti(a3F) and V(a4F), and excited, Ti(a5F) and V(a6D), states atoms with some simple molecules have been studied by a discharge‐flow tube technique. Laser‐induced fluorescence (LIF) was used to determine the concentration of the metal atoms as a function of the flow rate of the reactant molecule to obtain effective bimolecular rate constants. The rate constants of reactions with OX (X = O, N, N2) and H2S show strong inverse correlation with effective ionization potentials (I.P.‐Eel, where I.P. and Eel are ionization potential and electronic energy of metal atom) of the metal atoms. This result suggests that the electron transfer mechanism plays an important role in these reactions. The large rate constants for electronic excited states can be explained by the crossing between ionic and flat neutral potential energy surfaces. The inefficient reaction rates measured for ground states can be explained by the repulsive nature of 4s2 configuration which can result in a potential barrier.
Proton Tunneling In 5‐Chlorotropolone‐M1 (M = Kr, Xe, CH4) Van Der Waals Complexes
Authors: Sekiya Hiroshi , Nakajima Taiji , Hamabe Hidenori , Mori Akira , Takeshita Hitoshi , Nishimura Yukio
Published: September 2007

The S1‐S0 fluorescence excitation spectra of 5‐chlorotropolone‐M1 (M = Kr, Xe, CH4) van der Waals (vdW) complexes in the region near the electronic origin have been measured in a supersonic free jet to investigate the effect of the vdW interactions on proton tunneling. Tunneling splittings have been observed in the vdW vibrations as well as in the
transitions of the Kr and Xe complexes. The tunneling splitting of the 5‐chlorotropolone‐(CH4)1 complex is significantly smaller than those of the Kr and Xe complexes. It has been suggested that the vdW vibrations couple with intramolecular motions, leading to a higher potential energy barrier to tunneling in the CH4 complex. The results of the 5‐ chlorotropolone complexes have been compared to those of the tropolone complexes.
Optoacoustic Detection of Microparticles in Liquids at LaserFluences Below the Optical Breakdown Threshold
Authors: Alimpiev S. S. , Simanovskii Ya. O. , Egerev S. V. , Pashin A. E.
Published: September 2007

An optoacoustic device consisting of a XeCl excimer laser and a measurement cell with an attached
piezotransducer was used for detecting microparticles suspended in liquid probes. The potential of optoacoustic
diagnostics of microinhomogeneous liquids was enhanced by applying informative parameters
of optoacoustic response. Probes of distilled water and Dow Chemical latex suspension were used in
experiments. It was shown that cavitation mechanism of optoacoustic conversion taking place at laser
fluences below the optical breakdown threshold was well‐suited for individual microparticle detection.
The approach proposed is different from the well‐known breakdown counting optoacoustic technique.
Molecular Weight Distribution Generated on Initiation of Free RadicalPolymerization by Sequence of Laser Pulses
Authors: Evseev A. V. , Nikitin A. N.
Published: September 2007

An investigation of molecular weight distributions (MWDs) resulting from initiation of free radical
polymerization by an arbitrary sequence of short laser pulses has been undertaken. The analytical
expressions have been derived to calculate MWDs for a polymerization scheme that contains reactions of
chain initiation, propagation and termination by recombination or disproportionation. The MWDs
produced by pulse‐periodic irradiation have been calculated for a wide range of initiating pulses repetition
rates (f = 0.05–100 Hz). The MWD dynamics in the act of polymerization and the influence of the
duration of polymerization pseudostationary regime establishment upon the MWD have also been
studied. The suitability of the derived expressions for describing the MWD generated by CW radiation
before and after the establishment of polymerization quasi‐stationary regime has been considered.
Photodissociation Mechanisms of Benzene Cluster Ions on the Excitation With hv = 0.5‐3.0 eV
Authors: Ohashi Kazuhiko , Nakai Yasuhiro , Nishi Nobuyuki
Published: September 2007

The photodissociation of mass‐selected benzene cluster ions, (n = 2 − 8), is studied to elucidate the dynamics of dissociation and the mechanism of fragmentation. For , the average translational energy and the angular distributions of the photofragments are measured as a function of photon energy (hv). The photoexcitation to an upper bound state with hv = 2.81 eV results in statistical energy disposal. Regardless of the excitation to a dissociative state with hv = 1.17‐1.62 eV, only a small fraction (at most 10%) of the available energy is partitioned into the translation. For with n = 5‐8, the average number of neutral molecules ejected following photoexcitation increases linearly with increasing hv until is reached as the product. The result suggests that the photofragmentation proceeds via the sequential evaporation of neutral monomers rather than the direct ejection of a neutral cluster.
Photophysical Properties and Energy Transfer Dye Laser Characteristicsof 7‐Diethylamino‐3‐Heteroaryl Coumarin in Solution
Authors: Raju B. Bangar , Varadarajan T. S.
Published: September 2007

Photophysical properties and Energy transfer Dye Laser (ETDL) characteristics of a new dye:
7‐DiethylAmino Coumarin with a Heteroaryl substitution in the 3‐position (DACH), are presented.
The suitability of DACH as a laser dye has been verified on the basis of the absorption and
fluorescence characteristics in aprotic solvents. The dye laser characteristics of the dye pumped by
the available nitrogen laser have been successfully investigated in dimethylsulfoxide by energy transfer
dye laser mechanism, using coumarin 1 as a donor dye. DACH has been found to lase in the
blue‐green region of the visible spectrum. The experimental and theoretical values of energy transfer
rate constant (kET) and the critical transfer distance (R0) have been calculated in two different solvents
to determine the nature of energy transfer. The results indicate the dominance of resonance transfer
in this ETDL.
Competition Between Intramolecular Vibrational Energy Re‐Distribution and Unimolecular Dissociation: A Scattering Theoretical Point of View
Authors: Someda Kiyohiko , Nakamura Hiroki , Mies Frederick H.
Published: September 2007

Systematic behavior of decay rates of resonances above dissociation threshold is investigated by using the theory of resonance scattering. The condition for the Rice‐Ramsperger‐Kassel‐Marcus (RRKM) rate formula to be valid is clarified by analyzing the random model of unimolecular dissociation. The decay rate averaged over many resonances agrees with the RRKM rate when the mean spacing and the mean width of the resonance states coincide with each other. On the other hand, auto‐ and mutual‐correlation functions of the non‐stationary wave functions indicate a rather paradoxical and intriguing phenomenon: In the RRKM regime, insufficient time is left for intramolecular vibrational energy redistribution (IVR) before dissociation.
Spectroscopic Study of Hydrogen Bonded7‐Azaindole Clusters
Authors: Nakajima A. , Ono F. , Kihara Y. , Ogawa A. , Matsubara K. , Ishikawa K. , Baba M. , kaya k.
Published: September 2007

The geometric structures of 7‐azaindole (7‐AzI) and its dimer were investigated by laser‐induced fluorescence (LIF). The rotationally resolved LIF spectrum (resolution: ∼0.00003 cm-1 of 7‐AzI monomer shows that (i) rotational constants are A′′ 0.13082(5), B′′ = 0.05677(2), C′′ = 0.03970(1), A′ = 0.12468(5), B′ = 0.056752(2), and C′ = 0.03911(1), and (ii) the transition dipole moment direction is tilted at an angle of ± 21(5) degrees with respect to a axis. The LIF spectrum (resolution: ∼0.06 cm-1) of the nonreactive 7‐AzI dimer suggests there are three possibilities for the geometric structure, having “single bonded”, “T‐shaped”, and “non‐planar” structures.

The ionization energy of 7‐AzI was determined to be 8.1171(5) eV by using pulsed‐field ionization photoelectron spectroscopy (PFI‐PES). Several vibronic bands of 7‐AzI cation were observed and compared with those of neutral 7‐AzI in the S0 and S1 states. The electron binding energies of 7‐AzI cluster anions (2 ≤ n ≤ 5) were determined by photoelectron spectroscopy.
The C=O Stretching Frequency in the S1 (π* ‐ n) State of Acetaldehyde and its Deuterated Derivatives Determined With the Photofragment Excitation Spectroscopy
Authors: Kono Takumi , Takayanagi Masao , Hanazaki Ichiro
Published: September 2007

The vibrational structure was recorded for the S1 (π* ‐ n) state of acetaldehyde (CH3CHO) and its
deuterated derivatives (CH3CDO, CD3CHO and CD3CDO up to ∼3500 cm-1above the 0‐0 bands with
the LIF (laser induced fluorescence) and PHOFEX (photofragment excitation) techniques. In the
PHOFEX spectroscopy, the yield of the formyl radical, HCO() or DCO(), produced in the photodissociation
of acetaldehyde is measured against the excitation frequency. The yield was determined by
monitoring one of the rotational lines in the ←
transition of the formyl radical by the LIF technique. This is the first measurement of the vibronic structure of acetaldehydes in supersonic jets above the dissociation threshold where they are non‐fluorescent. The results have made it possible to locate v4 (the C=O stretching) and 2v4 bands unequivocally; the v4
fundamentals at 1217, 1189, 1210 and 1178 cm-1 above the 0‐0 band for CH3CHO, CH3CDO, CD3CHO and CD3CDO, respectively. The corresponding
overtone (2v4)
bands are observed, respectively, at 2414, 2350, 2399 and 2334cm-1. All the vibronic
bands newly observed in the PHOFEX spectra are found to be interpreted as the combinations of v4 and
2v4
with the modes appearing in the lower frequency (< 1200 cm-1) region, which consist of v10
(the
C—C—O in‐plane bending), v14 (the C=O out‐of‐plane wagging) and v15
(the methyl torsion).
A Time Resolved IR Laser Photolysis‐Laser Induced Fluorescence Study of theOH/Methanol Reaction
Authors: Riveros José M. , Barreta Luis Gilberto
Published: September 2007

The reaction of hydroxyl radicals (OH and OD) generated by infrared multiphoton dissociation of different
isotopomers of methanol were studied in the presence of variable amounts of Ar buffer gas. The
disappearance of the OH, or OD, radicals in the presence of the parent methanol was followed by laser
induced fluorescence at 310 nm. Comparison of the rate constants obtained from these experiments reveal
good agreement with observed isotope effects observed by other authors but suggest that the reactions
occurs at higher temperatures than the macroscopic bulk temperature of the sample.
Laser‐Induced Breakdown Spectroscopy of AL‐Samples: Application to ChemicalAnalysis of Metallic Elementsf
Authors: Bescós B. , Castaño J. , Ureña A. González
Published: September 2007

This paper reports on the simultaneous detection of Mg, Mn, Fe and Pb in Al samples using laser‐induced
breakdown spectroscopy and optical multichannel analysis of the photoablated microplasma. Using
calibrated samples, well characterized linear working curves were determined for these minor components
over the 0.01–1% concentration range. In addition optimum experimental conditions were found that
allow the analysis to be carded out in a fast and non‐invasive manner. The potential application of the
method to on‐line industrial analysis is also suggested.
Formation of Microparticles Initiated by Excimer Laser Photolysis of Mo(CO)6
Authors: Evseev A. V. , Kamayev S. V. , Sharipov R. H.
Published: September 2007

Formation of microparticles initiated by XeCl laser radiation photolysis of Mo(CO)6 mixed with buffer gas
was studied. It was shown that micron‐sized heavy objects (microparticles) of little mobility were formed
and scattered the beam of the He‐Ne probe laser. The microparticle mass and size were determined from
probe laser beam scattering. The average density of microparticle was estimated (ρ ≈ 0.1 g·cm-3).
Formation of the State‐Selected CH Radical Beam and its Application to The CH + NO Reaction
Authors: Takezaki M. , Ohoyama H. , Kasai T. , Kuwata K.
Published: September 2007

The CH(X2II) radical beam was produced via the decomposition of methanol by a dc‐discharge in a pulsed supersonic beam. The CH radical beam was rotationally state‐selected and separated from other discharge products by using an electrostatic hexapole field. The chemiluminescence from the reaction of CH in the |3/2, 3/2, 3/2> state with NO was measured under the crossed beam condition. The wavelength region of the present chemiluminescence confirms no NH(A3II) formation. The formation of HCN(X) and/or OH(X2II) is tentatively proposed.