title: Effect of laser pulse width on ionization efficiency in supersonic beam-multiphoton ionization-mass spectrometry.
abstract: The efficiency in multiphoton ionization is calculated for various molecules with different lifetimes, based on a kinetic model using rate equations. The results are strongly dependent on the types of resonance ionization, i.e., ionization through congested intermediate levels or ionization through a discrete intermediate level. In the former case, a laser pulse shorter than the lifetime is always preferred for efficient ionization. In the latter case, a 10-ps laser pulse provides the maximum ionization efficiency for a molecule with a lifetime in excess of 10 ps. For a molecule having a lifetime shorter than 10 ps, the use of a laser whose pulse width is adjusted to the same value as the lifetime is suggested. The results obtained by a computer simulation are in reasonably good agreement with the experimental data obtained for monohalogenated benzenes.
authors.affiliation: Department of Chemical Systems and Engineering, Graduate School of Engineering, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Matsumoto
authors.forename: T
authors.initials: T
authors.lastname: Imasaka