Temperature dependence of excitonic energy in isolated Se chains formed in channels of AlPO4-5 crystals

Abstract

Optical absorption spectra of Se chains formed in channels of AlPO4-5 (AFI) crystals are measured in the temperature range from 80 to 298 K. The excitonic energy of the isolated Se chains is observed to shift to lower energy linearly with increasing temperatures, in sharp contrast to the positive temperature coefficient in trigonal-Se crystal. The marked change in the temperature behavior of the excitonic energy is attributed to the greatly diminished interchain interaction in Se-AFI as well as the weakening of the electron-optical-phonon coupling in a low-dimensional system. © 1997 American Institute of Physics.