Mass spectrometry of D-ribose molecules

The results of mass spectra of D-ribose molecular beam study by electron impact for the 20-70 eV energy range at the evaporation temperature 310-430 K are presented. The experiment was carried out in two stages: first the mass spectra were measured in the range of 0-200 Da at different ionization energies, then relative cross-sections of single ionization of fragment ions were investigated in the electron energy range of 5-60 eV. The measured temperature dependences show the competing character of water and oxonium cation formation processes. It is the first determination of the appearance energy (AE) for the D-ribose molecule from the threshold region of the energy dependence of the effective ionization cross section. For the most intense fragment ions in the mass spectrum, the potentials of appearance are determined at the threshold of the dissociative ionization cross sections. Schemes for the fragmentation of positive D-ribose ions are proposed. (C) 2019 Elsevier B.V. All rights reserved.