title: Excited-state ions in femtosecond time-resolved mass spectrometry: an investigation of highly excited chloroamines.
abstract: We have investigated the processes induced by femtosecond laser pulses in chloroamines, with a focus on the generation and observation of a highly reactive radical and on the involvement and general importance of excited-state ions in time-resolved mass spectrometry investigations of gaseous molecules. We have found that 280 nm femtosecond pulses lead to an ultrafast breakage of the N-Cl bond on the repulsive S1 surface, and that resulting radical is long-lived. When exposing the molecule to 420 nm photons a multiphoton ionization takes place to generate ions; these ions can then be excited with a 280 nm photon. The evidence is unambiguous since we observe a distinct temporal evolution of the ion current with no photoelectrons to match. We suggest that the involvement of excited-state ions is a general phenomenon in time-resolved photoionization studies.
authors.affiliation: University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen.
authors.forename: Nerijus
authors.initials: N
authors.lastname: Rusteika
authors.forename: Rasmus Y
authors.initials: RY
authors.lastname: Brogaard
authors.forename: Theis I
authors.initials: TI
authors.lastname: Sølling
authors.forename: Fedor M
authors.initials: FM
authors.lastname: Rudakov
authors.forename: Peter M
authors.initials: PM
authors.lastname: Weber