Surface second harmonic generation from coumarin 343 dye-attached TiO2 nanoparticles at liquid–liquid interface

Abstract

The nonlinear optical properties of coumarin 343 (C343) dye-attached TiO 2 nanoparticles in the size range 5-8 nm adsorbed at the interface of water/1,2-dichloroethane have been studied by using the surface second harmonic generation technique. No second harmonic (SH) response was observed from the bare TiO 2 nanoparticles adsorbed at the interface, however, a strong SH response was measured from the dye molecules attached at the surfaces of the nanoparticles. The increase in the SH intensity with the increase of TiO 2 nanoparticle concentration in the aqueous solution of C343 is mainly due to the prealignment of the dye molecules at the surfaces of nanoparticles and is partly due to the third-order polarization contribution of the nanoparticles to the observed total SH response.

Interfacial Deposition of Titanium Dioxide at the Polarized Liquid–Liquid Interface

“…In two elegant works, Jensen et al [ 7 ] and later Plana and Fermin [ 8 ] showed that preformed TiO 2 nanoparticles self-assembled at the electrified water—1,2-dichloroethane (1,2-DCE) interface could be used to generate photocurrent responses when illuminated with laser light. Another report describes coumarin 343 dye TiO 2 nanoparticles complex interfacial adsorption studied with surface second harmonic generation technique [ 9 ]. The intuitive combination between conventional LLI and TiO 2 nanoparticles are Pickering emulsions that can be frequently found in everyday products (e.g., stabilized sun creams) or the scientific literature [ 10 , 11 , 12 ].…”