Ultrafast dissociation of ammonia: Auger Doppler effect and redistribution of the internal energy - Sorbonne Université Access content directly
Journal Articles Physical Chemistry Chemical Physics Year : 2022

Ultrafast dissociation of ammonia: Auger Doppler effect and redistribution of the internal energy

Edwin Kukk
  • Function : Author
Eero Itälä
  • Function : Author
John Bozek
Ralph Püttner

Abstract

We study vibrationally-resolved resonant Auger (RAS) spectra of ammonia recorded in coincidence with the NH2+ fragment, which is produced in the course of dissociation either in the core-excited 1s−14a11 intermediate state or the first spectator 3a−24a11 final state. Correlation of the NH2+ ion flight times with electron kinetic energies allows directly observing the Auger-Doppler dispersion for each vibrational state of the fragment. The median distribution of the kinetic energy release EKER, derived from the coincidence data, shows three distinct branches as a function of Auger electron kinetic energy Ee: Ee + 1.75EKER = const for the molecular band; EKER = const for the fragment band; and Ee + EKER = const for the region preceding the fragment band. The deviation of the molecular band dispersion from Ee + EKER = const is attributed to the redistribution of the available energy to the dissociation energy and excitation of the internal degrees of freedom in the molecular fragment. We found that for each vibrational line the dispersive behavior of EKERvs. Ee is very sensitive to the instrumental uncertainty in the determination of EKER causing the competition between the Raman (EKER + Ee = const) and Auger (Ee = const) dispersions: increase in the broadening of the finite kinetic energy release resolution leads to a change of the dispersion from the Raman to the Auger one.
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Dates and versions

hal-03598117 , version 1 (04-10-2022)

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Oksana Travnikova, Edwin Kukk, Farzad Hosseini, Sari Granroth, Eero Itälä, et al.. Ultrafast dissociation of ammonia: Auger Doppler effect and redistribution of the internal energy. Physical Chemistry Chemical Physics, 2022, Ivan Powis: Advances in Molecular Photoelectron Spectroscopy: Fundamentals & Application, 24 (10), pp.5842-5854. ⟨10.1039/D1CP05499F⟩. ⟨hal-03598117⟩
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