Liangzhi Xiao

POLAR ENHANCEMENT OF THE NONLINEAR-OPTICAL PROPERTIES OF FE2O3 MICROCRYSTALLITES

Abstract The dependence on surface environment of laser-induced luminescence and the nonlinear optical response of Fe 2 O 3 microcrystallites is studied. The luminescence is decreased, the third-order susceptibility enhanced, the excited state relaxation time is decreased and the reverse saturable absorption enhanced. These phenomena are analyzed in terms of the surface effect.

Study on the photo-induced interfacial charge transfer in TiO2/Fe2O3 heterostructured composite film

Heterostructured TiO 2 /Fe 2 O 3 composite film was obtained by spin-coating α-Fe 2 O 3 hydrosol on the TiO 2 nanoparticulate film prepared by the sol-gel method. The composite film was characterized by surface photovoltaic spectroscopy (SPS) and electric-field-induced surface photovoltaic spectroscopy (EFSPS), and the results showed that the composite film had the extended photovoltaic response which can be modified by the external electric field. Based on these results, a photoinduced interfacial charge transfer mechanism was deduced and the energy band structure of the composite film was concluded.

Preparation of covalently modified organic–inorganic composite nanoparticles and their interfacial electron transfer researches

TiO 2 and α-Fe 2 O 3 nanoparticles were covalently coated with an organic chromophore monolayer, 4-(4-N,N-(dialkylamino) styrl pyridium using trimethoxyl (p-(chloromethyl) phenyl) silane as linkage molecules. The resulting composite particles were characterized by UV-vis, IR, X-ray photoelectron spectroscopy (XPS), and surface photovoltaic spectroscopy (SPS). All the results indicated the formation of the organic-inorganic hybrid structures. The photoinduced interfacial charge transfer in the composite particles were also detected by SPS under different external voltages imposed.

Preparation of nanoparticulate Fe2O3—polymaleic monoester alternating Langmuir—Blodgett films with functional organic hydrophobic part

Abstract An organic functional group was introduced into the inorganic nanoparticle—organic alternating LB films by the use of the polymaleic monoester with a functional lateral chain to replace a fatty acid. Using the polymer (PMANN), the distance between adjacent nanoparticles in the LB films is apparently decreased and the distribution of the nanoparticles in the monolayer is more homegeneous than that in the nanoparticulate Fe 2 O 3 —stearate monolayer. All these phenomena are ascribed to the carboxylate groups of a polymer molecule bound to two or more nanoparticles. The photovoltage response of n-type (p-type) silicon coated with a monolayer of nanoparticulate Fe 2 O 3 —PMANN LB films increases (decreases) for two orders.

Self-trapped state and phonon localization in TiO2 quantum dot with a dipole layer

The discrete phonon spectra of TiO2 quantum dot with a dipole layer is reported. The absorption intensities of different LO phonons are related to the phonon‐electron coupling in accord with the prediction of the continuum polarization model. The two‐phonon bound state appeared due to the localization effect. The optical absorption of the self‐trapped state [reported in Appl. Phys. Lett. 59, 1826 (1991)] may be related to the strong electron‐phonon interaction in this system, i.e., a bipolaronic state might form with the presence of surface donor.