[15a-A405-1~7] 22.1 Joint Session M "Phonon Engineering"

[15a-A405-5] Mode-selective IR-inactive phonon-mode excitation with mid-infrared free-electron laser

Rei Akasegawa¹, Kyohei Yoshida⁴, Heishun Zen², 〇Kan Hachiya¹, Takuya Goto³, Takashi Sagawa¹, Hideaki Ohgaki² (1.Kyoto Univ., 2.IAE, Kyoto Univ., 3.Doshisha Univ., 4.CBMN, Univ. Bordeaux)

Keywords:mode-selective phonon-mode excitation, mid-infrared free-electron laser

The selective two FEL-photon excitation of an IR-inactive phonon-mode in single-crystal diamond, <em style="font-size:16px">T_2g optical mode at 1,332 cm^–1, was successfully confirmed by anti-Stokes Raman scattering. In a previous study, we developed a mode-selective phonon excitation method using mid-infrared (MIR) free-electron-laser (FEL). Nevertheless, it is simply one-photon absorption and restricted within so-called IR-active-vibrational-mode excitation. In the present study, we have developed further a two-photon selective-phonon-mode-excitation method to excite an IR inactive mode. We have revised the experimental setup, and successfully bypassed surface damage induced by a probing laser.