ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Thioacetaldehyde was prepared by the vacuum flash pyrolysis of 1, 3, 5-trimethyl-s-trithiane and was observed spectroscopically in a rapidly flowing system. The 614 nm absorption system of CH3CHS/CH3CDS/CD3CHS/CD3CDS was recorded photographically at path lengths of 72 m. Phosophorescence excitation and emission spectra of CH3CHS were observed with a cw dye laser. The assignment of the first absorption system was made to the spin forbidden transition a˜ 3A‘←X˜ 1A'. The bands observed in the region of the origin proved to have a very complex structure, and were assigned to torsional transitions. The observation of several hot band progressions which could be fitted to levels derived from microwave data gave the parameters V‘3 =534.3 cm−1, F‘=6.9950 cm−1, and ν0=16 293.8 cm−1 for CH3CHS. The fit to the excited state torsional levels was less satisfactory and gave V3 =94.18 cm−1, F'=5.3608 cm−1. An analysis of the data for the other isotopic species showed that the torsional motion in the upper state was coupled to a large amplitude wagging of the aldehydic hydrogen. The observed phase shift in the torsional angle on electronic excitation was attributed to the effects of hyperconjugation between the methyl hydrogens and the π (CS) orbitals.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.453554
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