In this work photodissociation studies of glyoxal-H2 (D2) molecules have been conducted in order to analyze the effect of the mass in the vibrational predissociation of van der Waals
complexes. The glyoxal-H2 (D2) molecules have been formed in a supersonic expansion and
photodissociated by means of a tunable dye laser. The final state of the glyoxal fragments
has been determined by the analysis of the fluorescence spectrum. A significant isotope effect
on the branching ratios for predissociation has been found. An interpretation in terms of a
distorted wave diabatic treatment is presented.

J. A. Beswick

N.  Halberstadt

C.  Jouvet

B.  Soep

Isotope Effect in the Vibrational Predissociation of van der Waals Molecules: Complexes of Glyoxal With H2 and D2

Experimental data for anthracene-argon van der Waals complexes are presented as a function
of bound argon atoms. The results are interpreted by a new theoretical model which is based
on the Hartree-Fock method and can explain molecular physical properties in the transition
region from isolated gaseous molecules to the condensed phase.

K.  Godzik

T. R. Hays

W. E. Henke

H. L. Selzle

E. W. Schlag

S. H. Lin

Effect of Formation of van der Waals Complexes on Molecular Physical Properties

Oxyhemoglobin photolysis has been investigated with picosecond laser techniques. Transient
light absorption changes observed within 500&#8211;600 nm reveal two processes following photodissociation:
electronic relaxation up to 400 ps after dissociation and a partial religation during 3 ns. The kinetics of oxygen geminate recombination at pH 7 and 22&#176;C has a monoexponential decay with a lifetime of 1.5 ns &#177; 0.1 ns.

P.  Valat

H.  Tourbez

B.  Alpert

Electronic Relaxation and Oxygen Recombination Processes in Photodissociated Oxyhemoglobin After Picosecond Flash Photolysis

This paper presents the results of observation of sputtering of neutral molecules and ions
from the crystal adenine surface induced by fourth-harmonic Nd:YAG laser radiation with a
pulse duration of 30 ps. The energy fluence of laser pulses was in the region (1&#8211;3) &#215; 10&#x2212;4
J/cm2. The kinetic energy distribution of the sputtered molecules spreads up to 0.7 eV. The
experiment shows that the threshold of adenine molecular ion sputtering is connected with
absorbed energy density in upper layers of the crystal surface but not by laser radiation
intensity.

V. S. Antonov

V. S. Letokhov

Yu. A. Matveyets

A. N. Shibanov

Sputtering of Neutral Molecules and Molecular Ions From the Adenine Crystal Surface Induced by the UV Picosecond Laser Pulse

We consider the influence of resonant laser excitation upon the dissociative reaction between
SF6 molecules and very low energy electrons. Experimentally, the use of valence electrons
of atoms in Rydberg states ensures a well-defined energy resolution of the scattering electrons
in the crossed beam apparatus. A spectroscopic model of the infrared absorption of CO2 laser
radiation by SF6 gives a fair determination of the energy levels and vibrational transitions
involved in the dissociative process. This reaction between highly excited atoms and a
molecule is interpreted as a three step process: attachment of a quasi-free electron, followed
by the interaction between the atomic ionic core and the negative molecular ion leading to
a partial stabilization and, finally, the competition between the dissociating and the autodetachment
channels.

R.  Barbe

J.-P.  Astruc

A.  Lagreze

J.-P.  Schermann

Spectral and Temperature Dependence of Laser Induced Dissociative Attachment in SF6

J. W. Perry

E. A. Ryabov

A. H. Zewail

Thermal Lensing Spectroscopy With Picosecond Pulse Trains and a
New Dual Beam Configuration

By using laser multiphoton ionization and a time-of-flight mass filter, we have detected
nascent UF5 from the 266 nm laser photodissociation of UF6, following a single laser firing.
The method can be used to monitor these species under conditions wherein isotopically selective excitation is responsible for the dissociation of UF6.

J. S. Chou

D.  Sumida

M.  Stuke

C.  Wittig

&#8220;Single Shot&#8221; Laser Multiphoton Ionization Detection of UF5 Following
the 266 <small.letters>nm</small.letters> Photodissociation of UF6

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Laser Chemistry