title: Atomiclike ionization and fragmentation of a series of CH3-X (X: H, F, Cl, Br, I, and CN) by an intense femtosecond laser.
abstract: Methane derivatives of CH(3)-X (X: H, F, Cl, Br, I, and CN) were ionized and fragmented by an intense femtosecond laser with a 40 fs pulse at 0.8 microm in intensities of 10(13)-10(15) W cm(-2). The curves of the ionization yields of CH(3)-X versus laser intensities have been found to be fitted with an atomic ionization theory (the theory of Perelomov, Popov, and Terent'ev) that has been established to reproduce experimental results well for rare gas atoms. The saturation intensities have been reproduced within a factor of 1.6 of the calculated ones. For molecules with low ionization potentials such as amines, another atomic ionization theory (the theory of Ammosov, Delone, and Krainov) reproduced the saturation intensities. The atomiclike ionization behavior of molecules indicates that the fragmentation occurs after the ionization. The fragmentation mechanisms after the ionization of some molecular ions are discussed.
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi, Osaka 558-8585, Japan.
authors.forename: Michinori
authors.initials: M
authors.lastname: Tanaka
authors.forename: Masanao
authors.initials: M
authors.lastname: Murakami
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Yatsuhashi
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Nakashima