Callahan Michael P, Crews Bridgit, Abo-Riziq Ali, Grace Louis, de Vries Mattanjah S, Gengeliczki Zsolt, Holmes Tiffani M, Hill Glake A
Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106-9510, USA.
Phys Chem Chem Phys. 2007 Aug 28;9(32):4587-91. doi: 10.1039/b705042a. Epub 2007 Jul 17.
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.
我们展示了通过激光解吸在超声速射流中注入黄嘌呤的共振双光子电离（R2PI）、紫外-紫外和红外-紫外双共振光谱。我们表明，黄嘌呤只有一种互变异构体，其在36700至37700厘米⁻¹的波长范围内吸收。红外-紫外双共振光谱在3444、3485和3501厘米⁻¹处显示出三个强带，我们将所有这些都归为N-H伸缩振动。将红外-紫外双共振光谱与从密度泛函理论（DFT）和二阶Møller Plesset（MP2）计算获得的频率和强度进行比较表明，观察到的黄嘌呤是二酮N(7)H互变异构体。
