Excited Products in the Photodissociation of Methyl Thiocyanate and Isothiocyanate in the Vacuum Ultra-violet

Abstract

Photolysis of CH3NCS and CH3SCN in the vacuum u.-v. produces fluorescence attributed to SCN excited radicals. In the case of CH3SCN production of CNB2∑+ system is also found. The threshold wavelength of incident photons for SCN formation is 197 ± 1 nm for CH3SCN and 188 ± 1 nm for CH3NCS. These values give D(CH3—SCN)= 3.04 eV and D(CH3—NCS)= 3.37 eV for the production of NCSA2Πi. A value of ΔHf(SCN)= 3.19 eV (76.4 kcal mol–1) has been calculated.