Photodissociation and photoionization of organosulfur radicals

Thesis/Dissertation · Fri May 27 00:00:00 EDT 1994

DOI:https://doi.org/10.2172/10190413· OSTI ID:10190413

Hsu, Chia-Wei ^[1]

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1. Iowa State Univ., Ames, IA (United States)

The dynamics of S(³P_2,1,0, ¹D₂) production from the 193 nm photodissociation of CH₃SCH₃, H₂S and CH₃SH have been studied using 2 + 1 resonance-enhanced multiphoton ionization (REMPI) techniques. The 193 nm photodissociation cross sections for the formation of S from CH₃S and HS initially prepared in the photodissociation of CH₃SCH₃ and H₂S are estimated to be 1 x 10^-18 and 1.1 x 10^-18 cm², respectively. The dominant product from CH₃S is S(¹D), while that from SH is S(³P). Possible potential energy surfaces involved in the 193 nm photodissociation of CH₃S($$\tilde{X}$$) and SH(X) have been also examined. Threshold photoelectron (PE) spectra for SH and CH₃S formed in the ultraviolet photodissociation of H₂S and CH₃SH, respectively, have been measured using the nonresonant two-photon pulsed field ionization (N2P-PFI) technique. The rotationally resolved N2P-PFI-PE spectrum obtained for SH indicates that photoionization dynamics favors the rotational angular momentum change ΔN < 0 with the ΔN value up to -3, an observation similar to that found in the PFI-PE spectra of OH (OD) and NO. The ionization energies for SH(X²Π_3,2) and CH₃S($$\tilde{X}$$²E_3/2) are determined to be 84,057.5 ± 3 cm^-1 and 74,726 ± 8 cm^-1 respectively. The spin-orbit splittings for SH(X²Π_{3/2, 1/2}) and CH₃S($$\tilde{X}$$²E_{3/2, 1/2}) are found to be 377 ± 2 and 257 ± 5 cm^-1, respectively, in agreement with previous measurements. The C-S stretching frequency for CH₃S⁺($$\tilde{X}$$³A₂) is 733 ± 5 cm^-1. This study illustrates that the PFI-PE detection method can be a sensitive probe for the nascent internal energy distribution of photoproducts.

• Research Organization: Ames Lab., Ames, IA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 10190413
• Report Number(s): IS-T-1709; ON: DE95001687; TRN: 94:021244
• Resource Relation: Other Information: TH: Thesis (Ph.D.); PBD: 27 May 1994
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
SULFUR COMPOUNDS
PHOTOIONIZATION
DISSOCIATION
ORGANIC COMPOUNDS
RADICALS
MULTI-PHOTON PROCESSES
664400
400201
EXPERIMENTALLY DERIVED INFORMATION ON ATOMIC AND MOLECULAR PROPERTIES
CHEMICAL AND PHYSICOCHEMICAL PROPERTIES