STATE-SPECIFIC ION DESORPTION FROM DCOO SI(100) BY C-1S CORE EXCITATION/

Photon-stimulated ion desorpsion from deuterated formic acid chemisorb ed on Si(100) has been studied using pulsed synchrotron radiation by s tate-selective C 1s core excitation. It is clearly seen that state-spe cific ion desorption occurs. The D+ and CDO+ ion yields are shown to s trongly depend on sigma(C-D) and sigma*(C-O) excitation, respectively . The peak energy shifts in ion yield curves are observed. The third p eak shifts of D+ and CD+ ion yields could be assigned to doubly electr on excitations having small cross sections. Each excited state nature which contributes to ion desorption is discussed.