title: Resonant and nonresonant multiphoton ionization processes in the mass spectrometry of explosives.
abstract: Multiphoton ionization processes were studied for three types of explosives using a line-tunable ultraviolet femtosecond laser. When peroxides such as triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) were ionized through a nonresonant two-photon process, a molecular ion was dominantly observed by reducing the excess energy remaining in the ion. However, an aromatic nitro compound such as 2,4,6-trinitrotoluene (TNT) produced large signals arising from molecular and fragment ions by resonant two-photon ionization. In addition, only fragment ions were produced from a nonaromatic nitro compound such as 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), even when a resonant two-photon ionization process was employed, suggesting that a further reduction in excess energy would be necessary if a molecular ion were to be observed.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Kyushu University , 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
authors.forename: Akifumi
authors.initials: A
authors.lastname: Hamachi
authors.forename: Tomoya
authors.initials: T
authors.lastname: Okuno
authors.forename: Tomoko
authors.initials: T
authors.lastname: Imasaka
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Kida
authors.forename: Totaro
authors.initials: T
authors.lastname: Imasaka