Forbes, R;
Boguslavskiy, AE;
Wilkinson, I;
Underwood, JG;
Stolow, A;
(2017)
Excited state wavepacket dynamics in NO 2 probed by strong-field ionization.
The Journal of Chemical Physics
, 147
(5)
, Article 054305. 10.1063/1.4996461.
Preview |
Text
Forbes_JCP_NO2_2017.pdf - Published Version Download (11MB) | Preview |
Abstract
We present an experimental femtosecond time-resolved study of the 399 nm excited state dynamics of nitrogen dioxide using channel-resolved above threshold ionization (CRATI) as the probe process. This method relies on photoelectron-photoion coincidence and covariance to correlate the strongfield photoelectron spectrum with ionic fragments, which label the channel. In all ionization channels observed, we report apparent oscillations in the ion and photoelectron yields as a function of pumpprobe delay. Further, we observe the presence of a persistent, time-invariant above threshold ionization comb in the photoelectron spectra associated with most ionization channels at long time delays. These observations are interpreted in terms of single-pump-photon excitation to the first excited electronic X˜ 2A1 state and multi-pump-photon excitations to higher-lying states. The short time delay (<100 fs) dynamics in the fragment channels show multi-photon pump signatures of higherlying neutral state dynamics, in data sets recorded with higher pump intensities. As expected for pumping NO2 at 399 nm, non-adiabatic coupling was seen to rapidly re-populate the ground state following excitation to the first excited electronic state, within 200 fs. Subsequent intramolecular vibrational energy redistribution results in the spreading of the ground state vibrational wavepacket into the asymmetric stretch coordinate, allowing the wavepacket to explore nuclear geometries in the asymptotic region of the ground state potential energy surface. Signatures of the vibrationally “hot” ground state wavepacket were observed in the CRATI spectra at longer time delays. This study highlights the complex and sometimes competing phenomena that can arise in strong-field ionization probing of excited state molecular dynamics.
| Type: | Article |
|---|---|
| Title: | Excited state wavepacket dynamics in NO 2 probed by strong-field ionization |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1063/1.4996461 |
| Publisher version: | http://doi.org/10.1063/1.4996461 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10064646 |
Archive Staff Only
 |
View Item |
