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Coupled nuclear-electronic decay dynamics of O2 inner valence excited states revealed by attosecond XUV wave-mixing spectroscopy.pdf (887.83 kB)

Coupled Nuclear-Electronic Decay Dynamics of O2 Inner Valence Excited States Revealed by Attosecond XUV Wave-Mixing Spectroscopy

preprint
submitted on 12.10.2020 and posted on 13.10.2020 by Yen-Cheng Lin, Ashley Fidler, Arvinder Sandhu, Robert R. Lucchese, C. William McCurdy, Stephen Leone, Daniel Neumark
Multiple Rydberg series converging to the O2+ 𝑐 4Σ𝑢 state, accessed by 20-25 eV extreme ultraviolet (XUV) light, serve as important model systems for the competition between nuclear dissociation and electronic autoionization. The dynamics of the lowest member of these series, the 3sσg state around 21 eV, has been challenging to study owing to its ultra-short lifetime (< 10 fs). Here, we apply transient wave-mixing spectroscopy with an attosecond XUV pulse to investigate the decay dynamics of this electronic state. Lifetimes of 5.8±0.5 fs and 4.5±0.7 fs at 95% confidence intervals are obtained for v=0 and v=1 vibrational levels of the 3s Rydberg state, respectively. A theoretical treatment of predissociation and electronic autoionization finds that these lifetimes are dominated by electronic autoionization. The strong dependence of the electronic autoionization rate on the internuclear distance because of two ionic decay channels that cross the 3s Rydberg state results in the different lifetimes of the two vibrational levels. The calculated lifetimes are highly sensitive to the location of the 3s potential with respect to the decay channels; by slight adjustment of the location, values of 6.2 and 5.0 fs are obtained computationally for the v=0 and v=1 levels, respectively, in good agreement with experiment. Overall, an intriguing picture of the coupled nuclear-electronic dynamics is revealed by attosecond XUV wave-mixing spectroscopy, indicating that the decay dynamics are not a simple competition between isolated autoionization and predissociation processes.

Funding

DE-AC02-05CH11231

History

Email Address of Submitting Author

ycl@berkeley.edu

Institution

Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

Country

USA

ORCID For Submitting Author

0000-0002-0163-9776

Declaration of Conflict of Interest

No conflict of interest

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