Active control of chemical bond scission by site-specific core excitation

Abstract

Core-electron excitation has a possibility to induce selective chemical bond scission due to its special localization and selectivity. Active control of chemical bond scission was examined in photon stimulated ion desorption (PSID) of core-excited poly-methylmethacrylate (PMMA) thin film, methyl ester terminated self-assembled monolayer (MHDA SAM), its partially deuterated SAM (MHDA-d 3) and ethyl ester terminated SAM (EHDA). Site-selective chemical bond scissions were observed for all molecular systems in the C1s resonant excitations as specific desorptions of CH n +, CD n + ( n=1–3), and C 2H m + ( m=2–5) ions for PMMA and MHDA, MHDA-d 3, and EHDA, respectively. Particularly, PSID of CH n + ( n=1–3) ions observed at the σ *(O–CH 3) ← C1s(OCH 3) excitation of MHDA exhibits significant dependence on the incidence angle of synchrotron radiation light. The experimental results suggest that site-specific PSID by core excitation can be actively controlled by adjusting a molecular environment of a desorbing functional group and the direction of the electric field vector of the incidence light.