Excited state dynamics in SO2. I. Bound state relaxation studied by time-resolved photoelectron-photoion coincidence spectroscopy

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DOIResolve DOI: http://doi.org/10.1063/1.4875035
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TypeArticle
Journal titleJournal of Chemical Physics
ISSN0021-9606
Volume140
Issue20
Article number204301
Pages15; # of pages: 5
SubjectDynamics; Excited states; Photoelectron spectroscopy; Photoelectrons; Probes; Sulfur dioxide; Ultrashort pulses; Wave packets; Excited-state dynamics; Inter-system crossings; Multiphoton ionisation; Photoelectron signals; Photoelectron-photoion coincidence; Time domain description; Time-resolved photoelectron spectroscopy; Ultrafast relaxation; Photons
AbstractThe excited state dynamics of isolated sulfur dioxide molecules have been investigated using the time-resolved photoelectron spectroscopy and time-resolved photoelectron-photoion coincidence techniques. Excited state wavepackets were prepared in the spectroscopically complex, electronically mixed (B̃)1B1/(Ã)1A2, Clements manifold following broadband excitation at a range of photon energies between 4.03 eV and 4.28 eV (308 nm and 290 nm, respectively). The resulting wavepacket dynamics were monitored using a multiphoton ionisation probe. The extensive literature associated with the Clements bands has been summarised and a detailed time domain description of the ultrafast relaxation pathways occurring from the optically bright (B̃)1B1 diabatic state is presented. Signatures of the oscillatory motion on the (B̃) 1B1/(Ã)1A2 lower adiabatic surface responsible for the Clements band structure were observed. The recorded spectra also indicate that a component of the excited state wavepacket undergoes intersystem crossing from the Clements manifold to the underlying triplet states on a sub-picosecond time scale. Photoelectron signal growth time constants have been predominantly associated with intersystem crossing to the (c̃)3B2 state and were measured to vary between 750 and 150 fs over the implemented pump photon energy range. Additionally, pump beam intensity studies were performed. These experiments highlighted parallel relaxation processes that occurred at the one- and two-pump-photon levels of excitation on similar time scales, obscuring the Clements band dynamics when high pump beam intensities were implemented. Hence, the Clements band dynamics may be difficult to disentangle from higher order processes when ultrashort laser pulses and less-differential probe techniques are implemented.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada; Security and Disruptive Technologies; NRC Steacie Institute for Molecular Sciences
Peer reviewedYes
NPARC number21272840
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Record identifier8e6b7e80-b29c-4847-9ef2-4f5df936e3df
Record created2014-12-03
Record modified2016-05-09
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