This is work done with the Ultrafast Laser Spectroscopy group at Wake Forest University: Eben Thoma, Hank Yochum and Pincipal Investogator Richard Williams.
Abstract
On the time scale of a few hundred femtoseconds to a few picoseconds after electron-hole pair creation in alkali halides, observations have revealed aspects of the growth and evolution of some familiar defect and self-trapped exciton absorption bands, as well as some more recently reported absorption features appearing at the earliest end of this time range and suggested by some workers to be transitions of 1-center self-trapped holes (N band), and of vibrationally hot and relaxing 2-center self-trapped holes (B band). We discuss recent observations relating to N-band spectra, present the first observation of a B band in CsBr, and present observations of Type II STE, Type III STE, and F center absorption formed in NaCl after electron-hole pair generation.