A multicoincidence study of fragmentation dynamics in collision of γ-aminobutyric acid with low-energy ions.
Fragmentation of the γ-aminobutyric acid molecule (GABA, NH(2)(CH(2))(3)COOH) following collisions with slow O(6+) ions (v≈0.3 a.u.) was studied in the gas phase by a combined experimental and theoretical approach. In the experiments, a multicoincidence detection method was used to deduce the charge state of the GABA molecule before fragmentation. This is essential to unambiguously unravel the different fragmentation pathways. It was found that the molecular cations resulting from the collisions hardly survive the interaction and that the main dissociation channels correspond to formation of NH(2)CH(2)(+), HCNH(+), CH(2)CH(2)(+), and COOH(+) fragments. State-of-the-art quantum chemistry calculations allow different fragmentation mechanisms to be proposed from analysis of the relevant minima and transition states on the computed potential-energy surface. For example, the weak contribution at [M-18](+), where M is the mass of the parent ion, can be interpreted as resulting from H(2)O loss that follows molecular folding of the long carbon chain of the amino acid.
CEA, UMR 6252 CIMAP, Boulevard Henri Becquerel, BP 5133, 14070 Caen cedex 5, France.
Michael
M
Capron
Sergio
S
Díaz-Tendero
Sylvain
S
Maclot
Alicja
A
Domaracka
Elie
E
Lattouf
Arkadiusz
A
Ławicki
Rémi
R
Maisonny
Jean-Yves
JY
Chesnel
Alain
A
Méry
Jean-Christophe
JC
Poully
Jimmy
J
Rangama
Lamri
L
Adoui
Fernando
F
Martín
Manuel
M
Alcamí
Patrick
P
Rousseau
Bernd A
BA
Huber