フェムト秒レーザーのパルス幅変化による有機分子のイオン化および解離過程

摘要

フェムト秒レーザーで有機分子をイオン化させる方法がFLMS（Femtosecond Laser Mass Spectrometry）であるト3）．この方法を伺いて，ポリ塩素化合物，ニトロ化合物，多環芳香族化合物，メタルカルポニル，および生物分子への応用が研究されている4.5）．しかし，応用を本格的に展開するためにはレーザー強度，レーザーパルス巾乱　 励起波長など多くの実験パラメーターを詳細に調べ，効率的な親イオン生成のためのデータベースを確立する必要がある．The ionization and fragmentation of 2,3-dimethyl-l,3-butadiene of a femtosecond laser have been studied at various pulse durations, which were changed from 35 fs to 1 ps. A reflectron-type time of flight mass spectrometer (TOF-MS) was used for ion detection. Molecules were ionized under a strong laser field and formed parent ions. Some were fragmented, resulting in a drastic increase of ionic species. Fragmentation was dominant when a long duration pulse was used, probably because the parent and large fragmented ions were further decomposed into small fragmented ions. Such heavy fragmentation may cause an underestimation of I(sat).