Fragmentation of D- and L-enantiomers of amino acids through interaction with $^3$He$^{2+}$ ions

The relative cross section of processes attendant on the capture of an electron by 12-keV $^3$He$^{2+}$ ions are measured by time-of-flight mass spectrometry for leucine (C$_6$H$_{13}$NO$_2$), methionine (C$_5$H$_{11}$NO$_2$S), and glutmic acid (C$_5$H$_9$NO$_4$) molecules. No differences between the formation relative cross sections of different fragment ions for the D- and L-enantiomeric forms of the amino acids are revealed. The spectrum of glutamic acid fragments taken at temperatures above 110$^\circ$C is explained by decomposition of the acid with the formation of pyroglutamic acid (C$_5$H$_7$NO$_3$) and water. The results are compared with published data on fragmentation of the same molecules via electron-impact ionization.