Ultrafast Dynamics on Titanium Dioxide
The main purpose of this research is to gain a fundamental understanding of interactions at the solid-gas interface, specifically on the TiO2 (titania) surface. Surface reaction dynamics studies are utilized to provide insight on mechanistic information for photoreactions on titania, particularly in heterogeneous catalysis.To monitor photoreaction dynamics in real time, we have developed an ultrafast laser setup seen below. For this system, we utilize a pulsed femtosecond Ti:Sapphire oscillator coupled to a Ti:Sapphire amplifier. The output pulsed beam is split into two independent beams, with different wavelengths generated by frequency mixing. In this pump-probe spectroscopic technique, the “pump” beam is used to initiate photoreactions on the surface, while the “probe” beam is used to ionize gas phase reaction products through (2+1) resonant enhanced multiphoton ionization (REMPI). Ionized photoproducts are detected by a Time-of-Flight spectroscopic technique.
With this setup, we can provide insight on the evolution of reaction products and transition state species in real time with sub-picosecond precision, paying close attention to relevant energy transfer timescales.