ナノ秒レーザーハイパーレイリー散乱法による光励起状態の超分子分極率評価

Abstract

A novel measurement system of hyperpolarizability beta at the excited state of molecules in solutions directly was constructed, which includes nanosecond Hyper-Rayleigh Scattering (HRS) method with Continuous Wave (CW) argon (Ar) laser excitation. The increase of HRS intensity for p-nitroaniline (pNA) was observed in methanol solutions upon excitation with Ar laser at 457.9 nm. The ratio of HRS intensities with and without excitation I(sub ex)/I(sub 0) depended on the concentration and the excitation power. Other possibilities for the observed increase such as Raman scattering, fluorescence, and the two photon process were excluded after detailed studies. It was concluded that the hyperpolarizability of pNA at the excited state is much higher than that at the ground state.

溶液中で分子の励起状態における超分子分極率βを直接に測定する新しいシステムを作り上げた。この測定にはCW(連続波)アルゴン(Ar)レーザ励起によるナノ秒ハイパーレイリー散乱(HRS)法を用いた。457.9nmでのArレーザ励起によりメタノール溶液内のp-ニトロアニリン(pNA)のHRS強度の増加が観測された。HRS強度比は励起I(sub ex)/I(sub 0)の有無に関係なく濃度と励起パワーに依存した。Raman散乱、蛍光、2光子過程のようなHRS強度の増加に対して他に考えられるものは、詳細に調べてから削除した。励起状態のpNAの超分子分極率は基底状態の場合よりはるかに高いと結論した。