Quantum Yields of H(2S) and CH3S(2E) from the Photolysis of Simple Organosulfur Compounds at 193, 222, and 248 nm

Abstract

The primary quantum yields for the formation of H(2S), @(H), and CH3S(2E), @(CH3S), in the photodissociation of methyl mercaptan, dimethyl sulfide (DMS), and dimethyl disulfide (DMDS) at the excimer laser wavelengths of 193, 222, and 248 nm were measured. @(H) were measured using resonance fluorescence detection of H atoms. The @(H) were 0.55 f 0.04 at 193 nm, 0.98 f 0.15 at 222 nm, and 1.09 f 0.25 at 248 nm for methyl mercaptan; (0.02 at 222 nm and <0.03 at 193 nm for DMS; and <0.06 at 222 nm and <0.08 at 193 nm for DMDS. No H atom production was observed in the 248 nm photolysis of DMS and DMDS. Using a selectively deuterated methyl mercaptan sample, CH3SD, it was shown that C-H bond scission is negligible in CH3SH photolysis at 193 and 248 nm. The @(CH3S), measured by CH3S detection via pulsed laserinduced fluorescence, were 0.93 f 0.21 at 248 nm and 0.78 f 0.10 at 193 nm for DMS; 1.65 f 0.38 at 248 nm and 1.20 f 0.14 at 193 nm for DMDS; and 0.48 f 0.10 at 193 nm for methyl mercaptan. The nature of the photodissociation processes in these sulfur compounds is discussed in light of the present measurements and the results of past studies.

Diminished cage effect in solid p-H2: Infrared absorption of CH3S observed from photolysis in situ of CH3SH, CH3SCH3, or CH3SSCH3 isolated in p-H2 matrices

“…52 As shown in Fig. The major channels for UV photolysis of CH 3 SSCH 3 , CH 3 SCH 3 , and CH 3 SH are CH 3 S+CH 3 S, CH 3 +CH 3 S, and CH 3 S+H, respectively.…”

“…52 At 193 nm, the C-S bond scission to produce CH 3 SS+ CH 3 becomes more important. 52 At 193 nm, the C-S bond scission to produce CH 3 SS+ CH 3 becomes more important.…”

State-to-state reaction dynamics of R+HCN (ν1νl22ν3)→RH+CN(v, J) with R=Cl, H

“…At 193 nm it equally competes with the SH cleavage. 17,18,19 The methanthiol in the present study was photolyzed at 266 nm generated from the fourth harmonic ͑15 mJ͒ of a Nd:YAG laser.…”

Reactions of O(3P) with Alkyl Iodides: Rate Coefficients and Reaction Products

“…The measured H atom signals were placed on an absolute basis by generating a known concentration of H atoms via the 248-nm photolysis of CH 3 SH (Φ ) 1 and σ ) 3.0 × 10 -19 cm 2 molecule -1 ). 32,33 From the measured detection sensitivity and the calculated [O] 0 , the branching ratio for H atom production was found to be 0.07 ( 0.02. To verify the determination of the CH 3 SH concentration, the rate coefficient for the H + CH 3 SH reaction was measured and found to be (2.1 ( 0.2) × 10 -12 cm 3 molecule -1 s -1 , in agreement with the value reported by Wine et al 32 The analysis of the H atom temporal profiles also yielded a rate coefficient of (7.9 ( 0.8) × 10 -12 cm 3 molecule -1 s -1 for the reaction of H atoms with CH 3 I, which was the primary loss process for H atoms in this system.…”