Photon-stimulated ion desorption from DCOO/Si(100) near the O K-edge

Photon-stimulated ion desorption from deuterated formic acid chemisorbed on Si(100) has been studied using pulsed synchrotron radiation in the energy region of the oxygen Is electron excitation. The O Is electrons of hydroxyl oxygen and carbonyl oxygen could be selectively excited in the O K-edge region because the chemical environments are different. It is found that the CDO* yield is enhanced at the O Is(C-O)-->sigma*(C-O) resonance and the CD+ yield at the O Is(C=O)-->sigma*(C-O) resonance. The results indicate that inn desorption is related both to the antibonding character of excited molecular orbitals and the local character of core hole orbitals. (C) 1997 Elsevier Science B.V.