Abstract
Controlling product branching ratios in a chemical reaction represents a desired but difficult achievement in chemistry. In this work, we demonstrate the first example of altering the branching ratios in a multichannel reaction, i.e., methanol dissociative chemisorption on Cu(111), via selectively exciting specific vibrational modes. To this end, we develop a globally accurate full-dimensional potential energy surface for the CH3OH/Cu(111) system and perform extensive vibrational state-selected molecular dynamics simulations. Our results show that O–H/C–H/C–O stretching vibrational excitations substantially enhance the respective bond scission processes, representing extraordinary bond selectivity. At a given total energy, the branching ratio of C–O/C–H dissociation can increase by as large as 100 times by exciting the C–O stretching mode which possesses an unprecedentedly strong vibrational efficacy on reactivity. This vibrational control can be realized by the well-designed experiment using a linearly polarized laser.
Highlights
Controlling product branching ratios in a chemical reaction represents a desired but difficult achievement in chemistry
The elongation of dissociative bonds at transition states has been observed for similar H2O9, CH410, and CO2 dissociations[17] on various metal surfaces, which is responsible for the vibrational enhancement on reactivity as suggested by Polanyi’s rules
Mode specificity and bond selectivity observed in CH3OH dissociation on Cu(111) can be readily understood by the so-called sudden vector projection (SVP) model[47,48]
Summary
Controlling product branching ratios in a chemical reaction represents a desired but difficult achievement in chemistry. We demonstrate the first example of altering the branching ratios in a multichannel reaction, i.e., methanol dissociative chemisorption on Cu (111), via selectively exciting specific vibrational modes To this end, we develop a globally accurate full-dimensional potential energy surface for the CH3OH/Cu(111) system and perform extensive vibrational state-selected molecular dynamics simulations. More importantly, methanol dissociation on metal surfaces is an ideal model system for better understanding the mode-specific and bond-selective chemistry since it involves the cleavage of three classes of chemical bonds (C–H, C–O, and O–H). It represents a prototype of reactions of complex organic molecules on metal surfaces[20]
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