The infrahyphen;red spectrum of crystalline benzene has been studied at minus;12deg;C, minus;65deg;C and minus;170deg;C as well as the liquid at 28deg;C. The lines are extremely sharp, the mean line width for fundamentals being 7 cmminus;1in the crystal. In three cases, it is less than the spectral slit width. All outhyphen;ofhyphen;plane degenerate modes are split by about 10 cmminus;1. Selection rules are obeyed and agree with the reported xhyphen;ray structure. All ungerade fundamentals are observed directly, some for the first time. Fiftyhyphen;two combination bands are observed. The frequency assignments of Ingoldet al.are confirmed except for theB2uspecies. Evidence is cited for rehyphen;assigning ngr;14from 1648 cmminus;1to 1310 cmminus;1and ngr;15from 1110 cmminus;1to 1150 cmminus;1. Ingold's isotopic data does not conflict with this change. Combination frequencies involving torsional lattice modes are apparently observed at minus;170deg;C.
展开▼
