Site-specific ion desorption from condensed C- and N-deuterated formamide near the carbon and nitrogen K-edge

Ion desorption from two types of condensed deuterated formamide was studied by site-specific core-electron excitation, Excitation of C 1s electron int o sigma* (C-D/N-H) antibonding orbital of condensed DCONH2 shows a very hig h desorption yield of D+ through the selective C-D bond fission. In contras t, no resonant peak was observed at the C 1s-->sigma* (C-D/N-H) excitation of condensed HCOND2. Excitation of N 1s electron into sigma* (C-H/N-D) anti bonding orbital of condensed HCOND2 relatively enhances the desorption yiel d of D+ compared with the total electron yield corresponding to the photoab sorption cross-section, whereas the desorption yield of DC was not enhanced at the N 1s-->sigma* (C-D/N-H) excitation of condensed DCONH2. Ion desorpt ion from condensed formamide thus depends on the antibonding character of t he excited state and also occurs around the chosen atomic site where the co re-electron excitation takes place. (C) 2000 Elsevier Science B.V. All righ ts reserved.