UV induced proton transfer in thioacetamide: first observation of thiol form of simple thioamideElectronic supplementary information (ESI): Tables S1 and S2 provide internal coordinates used in the normal mode analysis for the thione and thiol tautomers of thioacetamide. Atom numbering is given in Scheme S1. Infrared spectra of thioacetamide isolated in N2 and Ar matrices are compared in Figs. S1 and S2 with the spectra theoretically predicted at the DFT level. Table S3 provides the assignment of the bands observed in the IR spectra of thioacetamide (thione form) isolated in Ar and N2 matrices. The theoretically calculated spectra of four conformers of thioacetamide in the thiol tautomeric form are presented in Tables S4–S7. Optimised geome