title: Photoionization study of L-valine in the gas phase by vacuum ultraviolet synchrotron radiation.
abstract: The photoionization and photodissociation of L-valine are studied by tunable synchrotron vacuum ultraviolet photoionization mass spectrometry at the photon energy of 13 eV. The ionization energy of L-valine and the appearance energies of major fragments are measured by the photoionization efficiency spectrum in the photon energy range of 8-11 eV. Possible formation pathways of the major fragments, NH(2)CHC(OH)(2)(+) (m/z=75), NH(2)(CH(3))(2)(CH)(2)(+) (m/z=72) and NH(2)CHCO(+) (m/z=57), are discussed in detail with the theoretical calculations at the B3LYP/6-31++G (d, p) level. Hydrogen migration is considered as the key way for the formation of NH(2)CHC(OH)(2)(+) (m/z=75) and NH(2)CHCO(+) (m/z=57). Furthermore, other fragments, NH(2)CHCOOH(+) (m/z=74), (CH(3))(2)(CH)(2)(+) (m/z=56), C(4)H(7)(+) (m/z=55), NH(2)CHOH(+) (m/z=46), NH(2)CH(2)(+) (m/z=30) and m/z=18, species are also briefly described.
authors: National Synchrotron Radiation Laboratory and School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029, PR China.
authors: Shaohui
authors: S
authors: Zhou
authors: Genbai
authors: G
authors: Chu
authors: Lanlan
authors: L
authors: Cao
authors: Xiaobin
authors: X
authors: Shan
authors: Fuyi
authors: F
authors: Liu
authors: Ju-Guang
authors: JG
authors: Han
authors: Liusi
authors: L
authors: Sheng
mesh_terms: D013058:Mass Spectrometry / Q000379:methods*; D008958:Models, Molecular; D008968:Molecular Conformation; D055668:Photochemical Processes; D013237:Stereoisomerism; D017356:Synchrotrons; D014466:Ultraviolet Rays; D014618:Vacuum; D014633:Valine / Q000737:chemistry*
chemical_list: D014633:Valine