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 NCSA²Π_i. A value of ΔH_f(SCN)= 3.19 eV (76.4 kcal mol^–1) has been calculated.