193 nm laser photofragmentation time-of-flight mass spectrometric study of CS/sub 2/ and CS/sub 2/ clusters

Journal Article · Mon Feb 01 04:00:00 EST 1988 · J. Chem. Phys.; (United States)

OSTI ID:5647204

Tzeng, W; Yin, H; Leung, W; Luo, J; Nourbakhsh, S; Flesch, G D; Ng, C Y

A crossed laser and molecular beam photofragmentation apparatus is described. The apparatus is equipped with a rotatable molecular beam source and a translationally movable ultrahigh vacuum mass spectrometer for time-of-flight (TOF) measurements. Using this apparatus we have measured the TOF spectra of S and CS resulting from the photofragmentation processes, CS/sub 2/+h..nu..(193 nm)..-->..CS(X,v)+S(/sup 1/D or /sup 3/P). The translational energy distributions of photofragments derived from the S and CS TOF spectra are in good agreement. This observation, together with the finding that the TOF spectra of S and CS are independent of laser power in the 25--150 mJ range, shows that the further absorption of a laser photon by CS to form C(/sup 3/P)+S(/sup 3/P) within the laser pulse is insignificant. The TOF spectra of S obtained at electron ionization energies of 20 and 50 eV are indiscernible, indicating that the contribution to the TOF spectrum of S from dissociative ionization of CS is negligible at electron impact energies less than or equal to50 eV. The thermochemical thresholds for the S(/sup 1/D) and S(/sup 3/P) channels are determined to be 18.7 and 45.0 +- 0.4 kcal/mol, respectively, consistent with literature values. Structures found in the translational energy distribution can be correlated with vibrational structures of CS(X,v = 0--5) associated with the S(/sup 1/D) channel. The translational energy distribution supports the previous observation that the vibrational state distribution of CS(X,v) is peaked at v = 3.

• Research Organization: Ames Laboratory, U. S. Department of Energy and Department of Chemistry, Iowa State University, Ames, Iowa 50011
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 5647204
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 88:3; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640301 -- Atomic
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640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
BEAMS
CARBON COMPOUNDS
CARBON SULFIDES
CHALCOGENIDES
CHEMICAL REACTIONS
DECOMPOSITION
DISSOCIATION
ELECTROMAGNETIC RADIATION
LASER RADIATION
MASS SPECTROSCOPY
MOLECULAR BEAMS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
RADIATIONS
SPECTROSCOPY
SULFIDES
SULFUR COMPOUNDS
TIME-OF-FLIGHT METHOD