Exciton states in wide-gap materials CaF₂ and BaF₂ have been studied with the technique of two-photon spectroscopy using synchrotron radiation and laser. The two-photon excitation spectrum of CaF₂, and that of BaF₂ as well, exhibited a clear peak on the high-energy side of the $1S$ exciton energy. The peaks are attributed to the $2P$ states of the valence excitons. According to this assignment, the binding energies of the excitons have been determined to be 0.8 and 0.9 eV for CaF₂ and BaF₂, respectively. The signal intensities were larger than that in the case of one-beam excitation by a factor of about 500, which is attributed to a resonant effect on two-photon absorption.
No takes yet. Share an insight, caveat, or question.
Tsujibayashi et al. (1999) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context:
More from Physical review. B, Condensed matter