Vibrational state-selective autodetachment photoelectron spectroscopy from dipole-bound states of cold 2-hydroxyphenoxide: o-HO(C6H4)O-

摘要

We report a photodetachment and high-resolution photoelectron imaging study of cold 2-hydroxyphenoxide anion, o-HO(C6H4) O-, cooled in a cryogenic ion trap. Photodetachment spectroscopy revealed a dipole-bound state (DBS) of the anion, 25 +/- 5 cm(-1), below the detachment threshold of 18 784 +/- 5 cm(-1) (2.3289 +/- 0.0006 eV), i.e., the electron affinity of the 2-hydroxyphenoxy radical o-HO(C6H4)O-center dot. Twenty-two vibrational levels of the DBS are observed as resonances in the photodetachment spectrum. By tuning the detachment laser to these DBS vibrational levels, we obtain 22 high-resolution resonant photoelectron spectra, which are highly non-Franck-Condon due to mode-selective autodetachment and the Delta v = -1 propensity rule. Numerous Franck-Condon inactive vibrational modes are observed in the resonant photoelectron spectra, significantly expanding the vibrational information that is available in traditional high-resolution photoelectron spectroscopy. A total of 15 fundamental vibrational frequencies are obtained for the o-HO(C6H4)O-center dot radical from both the photodetachment spectrum and the resonant photoelectron spectra, including six symmetry-forbidden out-of-plane modes as a result of resonant enhancement. (c) 2015 AIP Publishing LLC.