Resonant enhancement effect on two-photon absorption due to excitons in alkaline-earth fluorides excited with synchrotron radiation and laser light

Abstract

Exciton states in wide-gap materials CaF 2 and BaF 2 have been studied with the technique of two-photon spectroscopy using synchrotron radiation and laser. The two-photon excitation spectrum of CaF 2 , and that of BaF 2 as well, exhibited a clear peak on the high-energy side of the 1S exciton energy. The peaks are attributed to the 2 P 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 CaF 2 and BaF 2 , 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. ͓S0163-1829͑99͒52836-1͔ RAPID COMMUNICATIONS

Two-photon absorption spectroscopy of As2S3 glass

“…26 This approximate coincidence implies that the two-photon absorption process in As 2 S 3 is governed by the states which give rise to the absorption tail. The process is probably resonantly enhanced by the states, 23 for which theoretical calculations including transition probabilities remain.…”

“…The residual absorption, mentioned above, may enhance probabilities of two-step absorption 22 and/or resonant two-photon absorption. 23 The second is to examine the role of these nonlinear absorption processes in such phenomena as photoinduced changes by low energy photons. 24,25 Photoinduced changes induced by near-infrared light cannot straightforwardly be ascribed to two-photon absorption, because onephoton absorption occurs in the weak-absorption tail.…”

Photostimulated detection of radiation defects produced by VUV light in BaF2

“…Recently we have constructed a combined system of synchrotron radiation (SR) and laser for research of solid-state physics and have applied it to two-photon spectroscopy of alkaline earth fluorides (Arimoto et al, 1998;Asaka et al, 1998;Azuma et al, 2001;Tsujibayashi et al, 1999Tsujibayashi et al, , 2005. In the present work, we have applied the system to the study of radiation damage in BaF 2 under irradiation by vacuum ultraviolet (VUV) light.…”

Time‐resolved study of Auger‐free luminescence in two‐photon excited BaF 2 with use of synchrotron radiation and laser

“…Excitation of core electrons by TPA has not been performed because there were no appropriate light sources. Recently, we have developed a measuring system of TPA where luminescence from the sample is detected and synchrotron radiation (SR) and laser are used as excitation light sources [2][3][4]. Spectral profiles of TPA by core electrons may reflect fruitful information especially on unoccupied electronic states.…”