Mode-Specific Autodetachment Dynamics of an Excited Non-valence Quadrupole-Bound State

Do Hyung Kang; Jinwoo Kim; Min Cheng; Sang Kyu Kim

doi:10.1021/acs.jpclett.1c00169

Mode-Specific Autodetachment Dynamics of an Excited Non-valence Quadrupole-Bound State

J Phys Chem Lett. 2021 Feb 25;12(7):1947-1954. doi: 10.1021/acs.jpclett.1c00169. Epub 2021 Feb 16.

Authors

Do Hyung Kang¹, Jinwoo Kim¹, Min Cheng^{1

2

3}, Sang Kyu Kim¹

Affiliations

¹ Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea.
² Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
³ University of Chinese Academy of Sciences, Beijing 100049, China.

PMID: 33591762
DOI: 10.1021/acs.jpclett.1c00169

Abstract

The autodetachment dynamics of vibrational Feshbach resonances of the quadrupole-bound state (QBS) for the first time has been investigated in real time for the first excited state of the 4-cyanophenoxide (4-CP) anion. Individual vibrational resonances of the cryogenically cooled 4-CP QBS have been unambiguously identified, and their autodetachment rates state-specifically measured using the picosecond time-resolved pump-probe technique employing the photoelectron velocity-map imaging method. The autodetachment lifetime (τ) is found to be strongly dependent on mode, giving τ values of ∼56, ∼27, and ≤2.8 ps for the 12'¹ (E_vib = 406 cm^-1), 12'² (E_vib = 806 cm^-1), and 21'¹ (E_vib = 220 cm^-1) modes, respectively. The striking mode-specific behavior of the QBS lifetime has been invoked by the physical model in which the loosely bound electron falls off by the dynamic wobbling of the three-dimensional quadrupole moment ellipsoid associated with the corresponding vibrational motion in the autodetachment process.