Y. Liu et al., Study of interfacial charge-transfer complex on TiO2 particles in aqueous suspension by second-harmonic generation, J PHYS CH B, 103(13), 1999, pp. 2480-2486
We report the first direct observation of an interfacial charge-transfer co
mplex using second-harmonic spectroscopy. The second-harmonic spectrum of c
atechol adsorbed on 0.4 micron-sized TiO2 (anatase) colloidal particles in
aqueous suspension reveals a charge-transfer band centered at 2.72 eV (456
nm). In addition, the adsorption isotherm of catechol on the colloidal TiO2
suspension was obtained and Save an excellent fit to the Langmuir adsorpti
on model. From this, we infer the free energy of the adsorption to be Delta
G degrees = -6.8 kcal/mol.