Vacuum Ultraviolet Photofragmentation of Sarcosine: Photoionization Mass Spectrometric and Theoretical Insights

摘要

Vacuum ultraviolet (VUV) photon-induced ionization and fragmentation of N-methyl glycine (sarcosine) were investigated with infrared laser desorption/tunable synchrotron VUV photoionization mass spectrometry (IR LD/VUV PIMS) and theoretical calculations. Fragment-controllable mass spectra of sarcosine were measuredat various photon energies. By tuning the photon energy, the fragments at m/z 44, 45, 43, 42, 30, and 60 were gradually detected. The ionization energy of the precursor was obtained by measuring the photoionization efficiency spectrum. Possible formation pathways of the fragment ions at m/z 44 (CH3NHCH2 +), 45 (CH3NH2CH2 +), 43 (CH2NHCH2 +), 42 (CH2NCH2 +), 30 (CH2NH2 +), and 60 (CH2COOH2 +) were discussed in detail with the help of calculations at the G3B3 and B3LYP/6-31++G(d,p) levels.