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Updated: Jul 13, 2026

Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization
Published on: August 6, 2018
IR-UV double resonance spectroscopy of xanthine
Michael P Callahan1, Bridgit Crews, Ali Abo-Riziq
1Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106-9510, USA.
Abstract:
We present resonant two-photon ionization (R2PI), UV-UV, and IR-UV double resonance spectra of xanthine seeded in a supersonic jet by laser desorption. We show that there is only one tautomer of xanthine which absorbs in the wavelength range of 36 700 to 37 700 cm(-1). The IR-UV double resonance spectrum shows three strong bands at 3444, 3485, and 3501 cm(-1), all of which we assign as N-H stretching vibrations. Comparison of the IR-UV double resonance spectrum with frequencies and intensities obtained from density functional theory (DFT) and second order Møller Plesset (MP2) calculations suggests that the observed xanthine is the diketo N(7)H tautomer.
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