MATRIX ISOLATION STUDY OF THE REACSATION OF FATOMS WITH C2H2C_{2}H_{2}. VIBRATIONAL SPECTRUM OF THE 2-FLUOROVINYL FREE RADICAL

Author Institution:Upon condeposition at 14 K of an $Ar:C_{2}H_{2}$ sample with an $Ar:CF_{4}$ sample that had been passed through a low-power microwave discharge, several new absorption appeared which could be assigned to the 2-fluorovinyl free radical. Detailed isotopic substitution studies support this assignment. The results of a least-squares force constant fit to the isotopic data will be presented. The infrared spectroscopic identification of the products of the secondary photodecomposition of the 2-fluorovinyl free radical will also discussed

MATRIX ISOLATION VS. QUANTUM CHEMISTRY FOR PREDICTING VIBRATIONAL FUNDAMENTALS OF SMALL FREE RADICALS

$^{a}$E. F. C. Byrd, C. D. Sherrill, and M. Head-Gordon, J. Phys. Chem. A 105, 9736 (2001).Author Institution: Optical Technology Division, National Institute of Standards and TechnologyThe average deviations from the gas-phase band centers of vibrational fundamental frequencies of 33 small molecular free radicals, recently calculated by Byrd, Sherrill, and Head-$Gordon^{a}$ using several commonly employed computational levels and basis sets, will be compared with the corresponding values characteristic of measurements in argon and neon matrices. Strategies will be suggested for estimating values for the ground-state vibrational fundamentals of small free radicals when detailed gas-phase data are not available

THE EFFECT OF HYDROGEN BONDING ON THE VIBRATIONAL SPECTRUM OF t-HOCO TRAPPED IN SOLID Ar AND CO

$^{1}$ D. E. Milligan and M. E. Jacox, J. Chem, Phys, 54, 927 (1971).Author Institution: Molecular Spectroscopy Division, National Bureau of StandardsThe OH stretching, in-plane OH deformation, and torsional fundamentals of t-HOCO, previously reported1 in a study of the vacuum-ultraviolet photolysis of $H_{2}O$ in a CO matrix, experience large shifts upon removal of the hydrogen-bonding perturbation by isolation of t-HOCO in solid argon. Because of these large shifts, a Fermi resonance perturbation of the $C=O$ stretching fundamental is altered, resulting in a substantial matrix dependence for the isotopic shift in this fundamental of t-DOCO. t-HOCO affords an unusual opportunity to study the effect of hydrogen bonding at either end of the molecule. Infrared spectral data for $OC\ldots H-O-C=O$, isolated t-HOCO, and $H-O-C=O\ldots HF$ will be compared

MATRIX ISOLATION STUDY OF THE REACTION OF F ATOMS WITH OXYGEN

Author Institution:The reaction of F atoms produced in a microwave discharge with oxygen in large excess of argon carrier gas leads to the appearance of very prominent infrared absorptions of $FO_{2}$ and of $F_{2}O_{2}$ in the spectrum of the reaction products trapped at 14 K. The $1550-cm^{-1}$ oxygen absorption is also activated in the initial deposit but diminishes in intensity on exposure of the sample to the Nernst glower background radiation used for the infrared studies. Infrared spectral data for the vibrational fundamentals and for several overtones and combination bands of normal and partially and fully oxygen-18 substituted $F0_{2}$ and $F_{2}0_{2}$ will be presented, and the vibrational assignment of $F_{2}$0$_{2}$ will be discussed. A search for the electronic absorption spectrum of F0$_{2}$, which has been found in these studies to photodissociate upon exposure of the sample to radiation of wavelength shorter than approximately 490 nm, will also be discussed

COMPARISON OF THE ELECTRONIC ENERGY LEVELS OF DIATOMIC MOLECULES IN THE GAS PHASE AND IN INERT SOLID MATRICES

Address: Molecular Spectroscopy Division, National Bureau of Standards, Gai thersburg, MD 20899.Author Institution:Electronic band origins and vibrational band spacings in excited electronic states have been compared for the approximately 230 electronic transitions of diatomic molecules which have been observed both in the gas phase and in rare-gas or nitrogen matrices. With few exceptions, valence transitions and the associated vibrational band spacings are shifted by less than about 1\% in neon matrices. Somewhat larger shifts, often to longer wavelengths, result from isolation of the molecule in a heavier rare-gas or a nitrogen matrix. The perturbation of Rydberg transitions by the matrix and the effects of charge-transfer interaction with the matrix will be discussed

COMPARISON OF THE GROUND-STATE VIBRATIONAL FUNDAMENTALS OF DIATOMIC MOLECULES IN THE GAS PHASE AND IN INERT SOLID MATRICES

Author Institution: Molecular Spectroscopy Division, National Bureau of StandardsDespite the voluminous literature on the spectra of diatomic molecules, there are many gaps in our knowledge of their ground-state vibrational frequencies. For many important diatomic molecules, only values obtained in matrix isolation experiments are available. In order to assess the likely extent of deviation of the ground-state vibrational fundamentals of diatomic molecules observed in rare-gas and nitrogen matrices from the gas-phase values, a systematic comparison has been made between gas-phase and matrix frequencies. The dependence of matrix shifts on the matrix material, type of chemical bond, and position of the elements in the Periodic Table will be considered for the approximately 225 pairs of observations which have been reported

THE INFRARED SPECTRA OF SMALL MOLECULAR IONS TRAPPED IN SOLID NEON

Author Institution: Molecular Physics Division, National Institute of Standards and TechnologyRecent studies of the infrared spectra of small molecular ions produced on photoionization and/or Penning ionization of the parent molecule by discharge-excited neon and subsequently trapped in solid neon will be reviewed. Emphasis will be placed on the correspondence between neon-matrix and gas-phase frequencies and on the determination of the structures and chemical bonding properties of simple molecular ions and dimer ions