Two-photon photosensitized singlet oxygen production from colloidal TiO2 solution

PHYS 444

Wenbing Li, wenbinglee@gmail.com, Naveen Gandra, naveen.gandra@jsums.edu, Shavelle N. Courtney, Scourtney2003@yahoo.com, and Ruomei Gao, ruomei.gao@jsums.edu. Department of Chemistry, Jackson State University, 1400 J R Lynch St, Jackson, MS 39217
1-3 nm rutile TiO2 nanoparticles prepared by TiCl4 hydrolysis was studied by monitoring its luminescence at 1270 nm with the aids of a time-resolved Nd:YAG laser and a low temperature Ge photodiode detector equipped with a 1270 nm interference filter and a 800 nm cutoff filter between the sample and detector. Double logarithm plot showed that singlet oxygen could be produced upon two-photon excitation of colloidal TiO2 nanoparticles under visible illumination in a focused laser beam at 532 nm. The lifetimes of singlet oxygen generated from TiO2 nanoparticles are several times shorter than those from organic photosensitizers due to the fast decay of singlet oxygen at the TiO2 surface.