Vibrational State-Selective Resonant Two-Photon Photoelectron Spectroscopy of AuS(-) via a Spin-Forbidden Excited State.
Vibrational state-selective resonant two-photon photoelectron spectra have been obtained via a triplet intermediate state ((3)Σ(-)) of AuS(-) near its detachment threshold using high-resolution photoelectron imaging of cryogenically cooled AuS(-) anions. Four vibrational levels of the (3)Σ(-) excited state are observed to be below the detachment threshold. Resonant two-photon absorptions through these levels yield vibrational state-selective photoelectron spectra to the (2)Σ final state of neutral AuS with broad and drastically different Franck-Condon distributions, reflecting the symmetries of the vibrational wave functions of the (3)Σ(-) intermediate state. The (3)Σ(-) excited state is spin-forbidden from the (1)Σ(+) ground state of AuS(-) and is accessed due to strong relativistic effects. The nature of the (3)Σ(-) excited state is confirmed by angular distributions of the photoelectron images and quantum calculations.
†Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States.|‡Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
Hong-Tao
HT
Liu
†Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States.
Dao-Ling
DL
Huang
§Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China.
Yuan
Y
Liu
§Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China.
Ling-Fung
LF
Cheung
†Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States.
Phuong Diem
PD
Dau
§Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China.
Chuan-Gang
CG
Ning
†Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States.
Lai-Sheng
LS
Wang
cold anions; electrospray ionization; gold sulfide; photoelectron spectroscopy; velocity-map imaging; vibrational state selection