The electronic spectra of thienolsqb;3,2,hyphen;brsqb;thiophene

摘要

The uv spectrum of thiophthene is investigated in the vapor and crystal phase. Two intense absorption systems in the region 36thinsp;000ndash;40thinsp;000 cmminus;1are assigned to two allowed electronic transitions toBuexcited states, while a very weak absorption observed in the crystal spectrum at 34thinsp;394 cmminus;1is assigned to a singlendash;triplet transition allowed by spinhyphen;orbit interactions.AbinitioCI computations of the energies of the excited states and relevant singletndash;triplet spinhyphen;orbit matrix elements provide support for the assignment. The vibrational analysis of the first intense absorption system suggests that the molecule has a distorted geometry in the first excited electronic state. An explanation is offered of the very different vibrational structure of the vapor and crystal spectra.