The ejection of triatomic molecular hydrogen ions H 3 + produced by the interaction of benzene molecules with ultrafast laser pulses
Year: 2009
Authors: Kaziannis S., Liontos I., Karras G., Corsi C., Bellini M., Kosmidis C.
Autors Affiliation: Department of Physics, Atomic and Molecular Physics Laboratory, University of Ioannina, Ioannina GR-45110, Greece; Lens Institute, University of Florence, via Nello Carrara 1, Sesto Fiorentino 50019, Italy; Department of Physics, Strathclyde University, SUPA, 107 Rottenrow East, Glasgow G4 0NG, United Kingdom
Abstract: The ejection process of triatomic molecular hydrogen ions produced by the interaction of benzene with ultrafast laser pulses of moderate strong intensity (~ 10 14 W/ cm 2) is studied by means of TOF mass spectrometry. The H 3 + formation can only take place through the rupture of two C-H bonds and the migration of hydrogen atoms within the molecular structure. The H 3 + fragments are released with high kinetic energy (typically 2-8 eV) and at laser intensities 10 14 W/ cm 2, well above that required for the double ionization of benzene, suggesting that its formation is taking place within multiply charged parent ions. The relative ejection efficiency of H 3 + molecular hydrogen ions with respect to the atomic ones is found to be strongly decreasing as a function of the laser intensity and pulse duration (67-25 fs). It is concluded that the H 3 + formation is only feasible within parent molecular precursors of relatively low charged states and before significant elongation of their structure takes place, while the higher multiply charged molecular ions preferentially dissociate into H + ions. The ejection of H 2 + ions is also discussed in comparison to the production of H 3 +and H + ions. Finally, by recording the mass spectra of two deuterium label isotopes of benzene (1,2- C 6 H 4 D 2, 1,4- C 6 H 4 D 2) it is verified that the ejection efficiency of some molecular fragments, such as D 2 H +, DH +, is dependent on the specific position of hydrogen atoms in the molecular skeleton prior dissociation.
Journal/Review: JOURNAL OF CHEMICAL PHYSICS
Volume: 131 (14) Pages from: 144308-1 to: 144308-9
More Information: 212025. 228334. Seventh Framework Programme, FP7. – The research leading to the results of the present work has received funding from the EC Seventh Framework Programme (FP7/2007-2013) under Grant No. 228334, Contract No. 212025. S.K. would like to thank Dr. Stefano Santabarbara (Center of Fundamental Research in Photosynthesis) for fruitful discussions during the preparation of the manuscript.KeyWords: Benzene molecules; C-H bond; Charged state; Double ionization; Ejection efficiency; Ejection process; Hydrogen atoms; Laser intensities; Mass spectra; Molecular fragments; Molecular hydrogen; Molecular ions; Molecular precursor; Molecular skeleton; Parent ions; Pulse durations; ToF mass spectrometry; Triatomic molecular; Ultrafast laser pulse, Atoms; Benzene; Deuterium; Hydrogen; Hydrogen bonds; Laser pulses; Lasers; Mass spectrometers; Mass spectrometry; Pulsed laser applications; Ultrafast phenomena, IonsDOI: 10.1063/1.3246832Citations: 16data from “WEB OF SCIENCE” (of Thomson Reuters) are update at: 2024-11-17References taken from IsiWeb of Knowledge: (subscribers only)