Photoionization mass spectrometry of CH[sub 2]S and HCS

Journal Article · Mon Feb 15 00:00:00 EST 1993 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.464139· OSTI ID:6769546

Ruscic, B; Berkowitz, J ^[1]

---

1. Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

The transient species CH[sub 2]S and HCS were studied by photoionization mass spectrometry. They were prepared [ital in] [ital situ] from CH[sub 3]SH by sequential hydrogen abstraction with fluorine atoms. CH[sub 2]S was also prepared by pyrolysis of CH[sub 3]SCl and CH[sub 3]SSCH[sub 3]. The photoion yield curve of CH[sub 2]S displays an abrupt threshold, and is similar in overall shape to that of the homologue CH[sub 2]O. The adiabatic ionization potential of CH[sub 2]S is found to be 9.376[plus minus]0.003 eV. Evidence has been found for [ital nd] and/or [ital ns] and [ital np] Rydberg states converging to the first excited state of CH[sub 2]S[sup +]. In addition, the HCS[sup +] fragment from CH[sub 2]S has been determined to appear at [le]11.533[plus minus]0.021 eV at 0 K. In contrast to CH[sub 2]S, the photoion yield curve of HCS[sup +] from HCS displays a very broad Franck--Condon envelope, consistent with a transition from bent HCS to linear HCS[sup +]. A Poisson fit to the experimental Franck--Condon factors indicates that the adiabatic ionization potential of HCS is [le]7.499[plus minus]0.005 eV, and perhaps as low as 7.412[plus minus]0.007 eV. The fragment curves at [ital m]/[ital e]=46, 47, 48, and 49 from CH[sub 3]SSCH[sub 3] have also been examined, and their relative shifts in energy determined. Together with measurements on CH[sub 2]S and HCS, and the previously reported [Delta][ital H][sup [circ]][sub [ital f]]0 (CH[sub 2]SH[sup +])=211.5[plus minus]2.0 kcal/mol ([le]213.1[plus minus]0.2 kcal/mol), this is sufficient to establish [Delta][ital H][sup [circ]][sub [ital f]]0 (CH[sub 2]S)=28.3[plus minus]2.0 kcal/mol ([le]29.9[plus minus]0.9 kcal/mol) and [Delta][ital H][sup [circ]][sub [ital f]]0 (HCS)=71.7[plus minus]2.0 kcal/mol ([le]73.3[plus minus]1.0 kcal/mol), ([ge]69.7[plus minus]2.0 kcal/mol). These values are in very good agreement with recent [ital ab] [ital initio] calculations.

• DOE Contract Number: W-31-109-ENG-38
• OSTI ID: 6769546
• Journal Information: Journal of Chemical Physics; (United States), Vol. 98:4; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
METHYL RADICALS
PHOTOIONIZATION
ORGANIC SULFUR COMPOUNDS
ADIABATIC PROCESSES
FRANCK-CONDON PRINCIPLE
IN-SITU PROCESSING
IONIZATION POTENTIAL
MASS SPECTROSCOPY
PHOTOEMISSION
POISSON EQUATION
PYROLYSIS
RADICALS
RYDBERG STATES
TEMPERATURE ZERO K
YIELDS
ALKYL RADICALS
CHEMICAL REACTIONS
DECOMPOSITION
DIFFERENTIAL EQUATIONS
EMISSION
ENERGY LEVELS
EQUATIONS
EXCITED STATES
IONIZATION
ORGANIC COMPOUNDS
PARTIAL DIFFERENTIAL EQUATIONS
PROCESSING
SECONDARY EMISSION
SPECTROSCOPY
THERMOCHEMICAL PROCESSES
400500* - Photochemistry