Ultrafast Interfacial Proton-Coupled Electron Transfer
Bin Li,1
Jin Zhao,1
Ken Onda,1
Kenneth D. Jordan,2
Jinlong Yang,3
Hrvoje Petek1*
The coupling of electron and nuclear motions in ultrafast charge transfer at molecule-semiconductor interfaces is central to many phenomena, including catalysis, photocatalysis, and molecular electronics. By using femtosecond laser excitation, we transferred electrons from a rutile titanium dioxide (110) surface into a CH3OH overlayer state that is 2.3 ± 0.2 electron volts above the Fermi level. The redistributed charge was stabilized within 30 femtoseconds by the inertial motion of substrate ions (polaron formation) and, more slowly, by adsorbate molecules (solvation). According to a pronounced deuterium isotope effect (CH3OD), this motion of heavy atoms transforms the reverse charge transfer from a purely electronic process (nonadiabatic) to a correlated response of electrons and protons.
1 Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA.
2 Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA.
3 Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China.
* To whom correspondence should be addressed. E-mail: petek{at}pitt.edu
