Abstract
All previous experimental and theoretical studies of molecular interactions at metal surfaces show that electronically nonadiabatic influences increase with molecular velocity. We report the observation of a nonadiabatic electronic effect that follows the opposite trend: The probability of electron emission from a low- work function surface-Au(111) capped by half a monolayer of Cs- increases as the velocity of the incident NO molecule decreases during collisions with highly vibrationally excited NO(X-2 Pi(1/2), V = 18; V is the vibrational quantum number of NO), reaching 0.1 at the lowest velocity studied. We show that these results are consistent with a vibrational autodetachment mechanism, whereby electron emission is possible only beyond a certain critical distance from the surface. This outcome implies that important energy- dissipation pathways involving nonadiabatic electronic excitations and, furthermore, not captured by present theoretical methods may influence reaction rates at surfaces.
Original language | English |
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Pages (from-to) | 1191-1194 |
Number of pages | 4 |
Journal | Science |
Volume | 321 |
Issue number | 5893 |
DOIs | |
Publication status | Published - 29 Aug 2008 |