The 5 μs-resolved CO emission spectra with spectral resolution of 0.25 cm−1 acquired in the range of 1900–2200 cm−1 after photolysis in the presence of Ar at 3000 mTorr.
Boltzmann plot of ln[N v, J /(2J + 1)] versus E v, J for CO in the v = 1, 2, and 3 levels at zero delay time in the presence of Ar, yielding the corresponding rotational temperature of 1429 ± 42, 1290 ± 53, and 1126 ± 71 K, respectively. N v, J is the relative population of CO in the (v, J) level and E v, J is the corresponding rotational energy.
Time evolution of CO vibrational population in the v = 1, 2, and 3 level. The population in each level reaches the maximum at 0 μs delay after signal correction with a scaling factor.
Population decay of OCS(v3) and CH2CO(v2) in the 1950–2080 and 2100–2200 cm−1 region, respectively, after 10 μs delay. OCS starts from v = 6 at 1957 cm−1, relaxes toward low v, and finally vanishes after 280 μs delay. CH2CO(v2) at 2150 cm−1 having partial overlap with OCS seems to decay downward.
Identification of CH3SH, CH4, and H2S in the 2400–3300 cm−1 region. The spectral region contains three profiles at about 2590, 2920, and 3000 cm−1. CH3SH(v3) and H2S(v1,v3) contribute to the first region, CH3SH(v2) dominates the second one, while CH4(v3) dominates the third one.
Time-resolved CO2 spectra within the 2300–2400 cm−1 region with a 12 cm−1 resolution resulting from the reaction of CH2 with O2 at 3000 mTorr.
(a) Area integrated over a low-resolution spectral band of CO2 as a function of delay time with respect to the laser pulse. (b) A plot of ℓn ([CO2]max–[CO2]) versus delay time, yielding a production rate constant of CO2. [CO2]max denotes the maximum concentration in (a).
Comparison of CO spectra produced between Ar and O2 addition at the same 3000 mTorr. The O2 addition leads to a slight enhancement of CO especially in the 1800–2050 cm−1 region.
Comparison of the spectra in the 2500-3300 cm−1 region following photolysis of CH3C(O)SH at 248 nm in the presence of Ar or O2 at the same pressure of 2800 mTorr. H2CO (v1) appears in the 2600–2900 cm−1 region after 5 μs and remains at 10 μs delay caused by the reaction of CH2 with O2.
Vibrational population of CO product obtained by (a) experimental observation, (b) prior distribution of CH2 + H2S + CO, and (c) prior distribution of CH3SH + CO. Population of CO(v = 1) is normalized for comparison.
The Ar pressure dependence of the CO area intensity over the low resolution spectra obtained at 0 μs delay. According to Eq. (9) in the text, the experimental data are fitted to yield the optimized rate constants in units of cm3 molecule−1 s−1 for the collision-induced internal conversion.
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