Shuji Asaka

Time-gated photon counting method for two-photon spectroscopy using synchrotron radiation and laser

A new measurement system has been developed for two-photon spectroscopy in solids with a combination of synchrotron radiation and laser. This system is based on a time-gated photon counting technique to observe luminescence signals induced by two-photon excitation. It is demonstrated that this technique enables us to achieve a high sensitivity and a good signal-to-noise ratio because it is a kind of zero method.

Amplification of impurity-associated Auger-free luminescence in mixed rubidium–caesium chloride crystals under core-level excitation with undulator radiation

Abstract The paper presents the results of experimental studies aimed at testing the amplification of impurity-associated Auger-free luminescence (275 nm band) in mixed rubidium–caesium chloride crystals under core-level excitation with undulator radiation. The emission features observed under the best collimation of the optical cavity, namely the enhancement of the peak intensity, the sharpening of the emission spectrum and the shortening of the luminescence decay, suggest a possibility of the light amplification due to inverted population between the valence and 5pCs-impurity core states. A further lasing performance with regard to possibilities for development of this technique is also briefly discussed.

Combined system of synchrotron radiation and laser for solid-state research.

Two combined systems of synchrotron radiation and laser have been constructed for solid-state research. One is a laser-induced fluorescence system to observe synchrotron radiation-induced desorption of alkali atoms from ionic crystals, which consists of a laser diode with a high repetition rate and synchrotron radiation under a single-bunch operation. The other is a system of two-photon spectroscopy, which is based on the combination of synchrotron radiation pulses with a low intensity and high repetition rate and Nd:YAG laser pulses with a high intensity and low repetition rate. The experimental systems and the preliminary results are presented in this report.