Development of Ultraviolet-Ultraviolet Hole-Burning Spectroscopy for Cold Gas-Phase Ions.
A new ultraviolet-ultraviolet hole-burning (UV-UV HB) spectroscopic scheme has been developed for cold gas-phase ions in a quadrupole ion trap (QIT) connected with a time-of-flight (TOF) mass spectrometer. In this method, a pump UV laser generates a population hole for the ions trapped in the cold QIT, and a second UV laser (probe) monitors the population hole for the ions extracted to the field-free region of the TOF mass spectrometer. Here, the neutral fragments generated by the UV dissociation of the ions with the second laser are detected. This UV-UV HB spectroscopy was applied to protonated dibenzylamine and to protonated uracil. Protonated uracil exhibits two strong electronic transitions; one has a band origin at 31760 cm(-1) and the other at 39000 cm(-1). From the UV-UV HB measurement and quantum chemical calculations, the lower-energy transition is assigned to the enol-keto tautomer and the higher-energy one to the enol-enol tautomer.
†Physique des Interactions Ioniques et Moleculaires (PIIM) UMR 7345, CNRS, Aix Marseille Université, 13397 Marseille Cedex, France.
Géraldine
G
Féraud
†Physique des Interactions Ioniques et Moleculaires (PIIM) UMR 7345, CNRS, Aix Marseille Université, 13397 Marseille Cedex, France.
Claude
C
Dedonder
†Physique des Interactions Ioniques et Moleculaires (PIIM) UMR 7345, CNRS, Aix Marseille Université, 13397 Marseille Cedex, France.
Christophe
C
Jouvet
‡Department of Chemistry, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
Yoshiya
Y
Inokuchi
‡Department of Chemistry, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
Takeharu
T
Haino
‡Department of Chemistry, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
Ryo
R
Sekiya
‡Department of Chemistry, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
Takayuki
T
Ebata
conformers; electronic spectroscopy; gas-phase cold ion; ion traps; uracil