# THE ELECTRONIC SPECTRA OF THE HCCS AND DCCS FREE RADICALS

Please use this identifier to cite or link to this item: http://hdl.handle.net/1811/11521

Files Size Format View
1981-FC-08.jpg 86.87Kb JPEG image

 Title: THE ELECTRONIC SPECTRA OF THE HCCS AND DCCS FREE RADICALS Creators: Krishnamachari, S. L. N. G.; Ramsay, D. A. Issue Date: 1981 Abstract: High resolution and deuterium substitution studies are carried out on the transient absorption spectrum observed in the region 3770-4170 {\AA} in the flash-photolysis of $thiophene^{1}$. Flash photolysis experiments with partially and fully deuterated thiophenes show that the carrier of the spectrum contains only one hydrogen atom. The isotope shifts further show that the main progression-forming frequency of $740 cm^{-1}$ undergoes only a small reduction on deuteration ($15 cm^{-1}$), thereby indicating that it is essentially a non-hydrogenic vibration. Most of the strong bands obtained with $C_{4}H_{4}S$ and $C_{4}D_{4}S$ are photographed under high resolution in the 14th and 15th orders of a 7.3 m Ebert spectrograph and their structures show doublet P and R branches. The bands could be assigned to a $^{2}\Pi - {}^{2}\Pi$ electronic transition of a linear molecule with the possibility of its being slightly non-linear in one of the states. Consideration of the method of production, the magnitude of the rotational constants and the vibrational structure enables the assignment of the carrier to the HCCS free radical. URI: http://hdl.handle.net/1811/11521 Other Identifiers: 1981-FC-8