総説

時間分解フーリエ変換赤外分光法の開発と星間化学研究への応用

Development of Time-Resolved Fourier Transform Infrared Spectroscopy and Applications to Interstellar Chemistry

川口 建太郎
Kentarou KAWAGUCHI

高分解能フーリエ変換型分光器を用いて，時間分解分光装置を開発した．マイクロチップ・コンピューターSXまたはFPGAを利用して多重サンプリングを可能にし，一回の掃引で最大64個の時間データを取得できた．パルス放電，レーザーアブレーション生成物からの赤外発光の時間変化の測定に応用し，He₂では新しいRydberg状態を見出し，量子欠損理論により帰属を行った．H₃⁺ ν₂バンドの発光スペクトル線強度の減衰から，イオンと電子の再結合反応の速度定数を得た．

By using a high-resolution spectrometer, a time-resolved Fourier transform infrared spectroscopic method has been developed with the help of a microcontroller SX and/or FPGA, where a maximum of 64 time-resolved data are recorded with a preset time interval in a single scan of the interferometer. This method has been applied to observations of infrared emission spectra from pulsed discharge products such as CN, He₂, H₃+, HNC/HCN. He2 in Rydberg states with higher energy than the b³Π state was found to be produced efficiently in afterglow plasma, and the quantum defect theory was applied to identification of each line in electronic states originated from 5f and 6f orbitals. From the observed time-profiles of emission lines of the H₃+ ν₂ band, the rate constant for recombination reaction of H₃+ and electron has been estimated. The time-resolved system was also applied for emission lines from laser ablation products by using a high repetition rate Nd:YLF laser.

Keywords: Time-Resolved FT, Infrared Emission Spectra, CN Radical, He,₂, H₃+, laser ablation