Dissociative double photoionization of benzene molecules in the 26–33 eV energy range

Abstract

A time-of-flight mass spectrometer with a position sensitive ion detector was used to study the dissociative double ionization of benzene by UV synchrotron radiation. The threshold energy for the main dissociative processes, leading to CH(3)(+) + C(5)H(3)(+), C(2)H(3)(+) + C(4)H(3)(+) and C(2)H(2)(+) + C(4)H(4)(+) ion pairs were characterized by exploiting a photoelectron-photoion-photoion-coincidence technique, giving 27.8 ± 0.1, 29.5 ± 0.1, and 30.2 ± 0.1 eV, respectively. The first reaction also proceeds via the formation of a metastable C(6)H(6)(2+) dication. The translational kinetic energy of the ionic products was evaluated by measuring the position of ions arriving to the detector. Theoretical calculations of the energy and structure of dissociation product ions were performed to provide further information on the dynamics of the charge separation reactions following the photoionization event.

Selectivity in fragmentation of N-methylacetamide after resonant K-shell excitation

“…9f exhibits faint tail structures originating at 52, 53-1 and extending towards smaller m on the y-axis and larger m on the x-axis. These tails are a sign of metastable doubly-charged ions which undergo a delayed fragmentation as they propagate through the TOF tube 46,49 . The properties of the instrument imply that the lifetime of these metastable states are longer than 50 ns 46,49 .…”

“…These tails are a sign of metastable doubly-charged ions which undergo a delayed fragmentation as they propagate through the TOF tube 46,49 . The properties of the instrument imply that the lifetime of these metastable states are longer than 50 ns 46,49 . The integrated tail intensities listed in Table 4 reveal a propensity for increased abundance at the O1s 532 eV resonance.…”

Molecular Fragmentation of Acetylene by VUV Double Photoionization

“…In the latter case the so called molecular dications are produced. Molecular dications can be formed by different techniques, as mass spectrometry [8], ion-molecule reactions [9], and double photoionization processes [10][11][12][13]. They are stable or metastable [8,14] molecular species, and in the latter case they could be used, in principle, as energy storage at a molecular level [8,9,15].…”

The Escape of O^+ and CO^+ Ions from Mars and Titan Atmospheres by Coulomb Explosion of CO22+ Molecular Dications

“…These ionic species can be formed by using different techniques, as mass spectrometry [14], ion-molecule reactions [15], and double photoionization processes [16][17][18][19]. Molecular dications can be formed in stable or metastable states [13,19,20] and may be used, in principle, as energy storage at a molecular level [14,15,21]. Such species, and more in general multiply charged ions, can be produced also by cosmic rays, which are meaningful since they are ubiquitous and carry a large energy content (up to 100 GeV).…”