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

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-d3) 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 CHn+, CDn+ (n=1–3), and C2Hm+ (m=2–5) ions for PMMA and MHDA, MHDA-d3, and EHDA, respectively. Particularly, PSID of CHn+ (n=1–3) ions observed at the σ*(O–CH3) ← C1s(OCH3) 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.