Time-Resolved Sum Frequency Generation Reveals Adsorbate Migration between Different Surface Active Sites on Titanium Oxide/Pt(111)

Thermally driven migration of formate between two types of surface active sites on titanium oxide film supported on Pt(111) is successfully resolved by picosecond sum frequency generation (SFG) spectroscopy in combination with a laser-induced temperature jump technique. This kinetic process explains the in-phase thermal decomposition of formate adsorbed on these different surface active sites. The enthalpy difference (Delta H) between these formate species is estimated to be ca. 3 kJ mol(-1).