FIG. 6.
(a) GC-MS single-ion chromatograms (SICs) of the three residues produced from the UV/EUV irradiations of H2O:pyrimidine ice mixtures with the 0th order beam light (top trace, irradiation time: 20 h), the He i line (top middle trace, 32 h), and the He ii line (bottom middle trace, 32 h), for m/z=153 amu, which corresponds to the mass of singly oxidized pyrimidine derivatives. The bottom trace is the SIC of a 4(3H)-pyrimidone standard prepared and injected under the same conditions as the residues. (b) GC-MS SICs of the same three residues for m/z=283 amu, which corresponds to the mass of doubly oxidized pyrimidine derivatives. The bottom trace is the SIC of a uracil standard prepared and injected under the same conditions as the residues. Identifications of 4(3H)-pyrimidone and uracil in the residues are marked with arrows.