Summary Sharp fluorescence spectra of the phenyldimethylsilyl radical have been observed for the first time by the photolyses of phenyldimethylsilane, phenyltrimethylsilane, and phenylpentamethyldisilane at 77 K. The excitation spectrum observed for the sharp emission shows spectral characteristics similar to those of benzyl radicals and is well interpreted by the results of CNDO/S-CI calculations on the phenyldimethylsilyl radical. Fluorescence ...