Ultrafast dissociation of ammonia: Auger Doppler effect and redistribution of the internal energyShow others and affiliations
2022 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 24, no 10, p. 5842-5854Article in journal (Refereed) Published
Abstract [en]
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.
Place, publisher, year, edition, pages
Royal Society of Chemistry (RSC) , 2022. Vol. 24, no 10, p. 5842-5854
Keywords [en]
Ammonia, Degrees of freedom (mechanics), Dispersions, Dissociation, Excited states, Kinetic energy, Kinetics, Auger-Doppler, Electron kinetic energy, Intermediate state, Internal energies, Kinetic energy release, Molecular band, RAS spectrum, Resonant Auger, Ultrafast dissociation, Vibrationally resolved, Augers
National Category
Physical Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-321875DOI: 10.1039/d1cp05499fISI: 000759750400001PubMedID: 35195639Scopus ID: 2-s2.0-85126072496OAI: oai:DiVA.org:kth-321875DiVA, id: diva2:1713525
Note
QC 20221125
2022-11-252022-11-252022-11-25Bibliographically approved