We investigated the surface potential of the ferroelectric domains of the epitaxial PbTiO3 (PTO) films using both Kelvin probe and piezoresponse force microscopy. The surface potential changes as a function of applied biases suggested that the amount and sign of surface potentials depend on the correlation between polarization and screen charges. It also suggested that the trapped negative charges exist on the as-deposited PTO surfaces. Injected charges and their resultant surface potentials are investigated by grounded tip scans. The results unveiled the origin of surface potential changes during ferroelectric switching in the epitaxial PTO films.

Photocurrent of a single ZnO nanowire synthesized by a sol-gel route was investigated. In vacuum, the dark current was bigger but the photoresponse was slower than that in air, attributed to the release of the available charge carriers by the desorption of water molecules and the decrease of the exchange rates of molecular ions. Under the steady radiation of the ultraviolet light (λ=325nm), a gradual decrease of the photocurrent was noticeable, which can be explained in terms of the annihilation of the carriers by the replacement of hydroxyl groups (OH−) by O2−, resulting in the decrease of charge carriers.

Elimination reactions of aryl esters of arylacetic acids 1 and 2 promoted by R2NH in MeCN have been investigated kinetically. The reactions are second-order and exhibit β = 0.44−0.84, |βlg| = 0.41−0.50, and ρH = 2.0−3.6. Brønsted β and |βlg| decrease with the electron-withdrawing ability of the β-aryl substituent. Hammett ρH values remain nearly the same, but the |βlg| value increases as the base strength becomes weaker. Both ρH and β decrease with the change of the leaving group from 4-nitrophenoxide to 2,4-dinitrophenoxide. The results are consistent with an E2 mechanism and a reaction coordinate with a large horizontal component corresponding to proton transfer. When the base−solvent system is changed from R2NH−MeCN to R2NH/R2NH2 +−70 mol % MeCN(aq), the Brønsted β, ρH, and |βlg| decrease. Finally, the ketene-forming elimination reactions from p-nitrophenyl p-nitrophenylacetate promoted by R2NH/R2NH2 + buffers in 70 mol % MeCN(aq) have been shown to proceed by concurrent E2 and E1cb mechanisms.

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Using Kelvin force microscopy, the authors have investigated the potential distribution on ferroelectric films. The local distribution of potential was observed on downward, prepoled areas. The polarity of the potential corresponds to the screen charge. It was found that the electrical properties of the grain boundary affect the potential distribution. Most of the grain boundaries show a lower potential than the area inside the grain. The authors identified certain regions at the grain boundary with a very low potential. Such potential pits may act as efficient screen charge draining paths and may lead to important perturbations on the device level.

We report on the optoelectronic properties of the aligned SnO2 nanowire (NW) field effect transistors (FETs) fabricated via a sliding transfer of NWs grown by chemical vapor deposition. Photocurrent measurements with polarized UV light confirmed a well aligned NWs along the channels. UV photosensitivity of ∼107 at the gate voltage Vg=−40 V was obtained due to a small dark-current at the turn-off state of FET. The dynamic response of the photocurrent became faster for the higher mobility SnO2 NW FETs. We expect our aligned SnO2 NW FETs will be useful as polarized UV detectors with a high sensitivity.

Switching behavior of 90° domains in epitaxial Pb(Zr0.32Ti0.68)O3 thin films under applied bias voltage was investigated in situ using synchrotron x-ray diffraction, and contribution of the switching to ferroelectric P–E hysteresis curve could be estimated. The electric field in the region illuminated by x ray was made confined exactly normal to the film/substrate interface by patterning an isolated capacitor (1×1 mm2) and etching off the remainder in order to eliminate mechanical constraint from nonswitching region. The portion of polarization taken up by 90° domain reversal was separated from 180° domain switching after measuring the changes in relative intensity ratio of PZT (001) and (100) reflections, which exhibited hysteresis behavior depending on applied voltage. Within the experimental region of electric field up to 24 kV/mm, maximum 27.8% of 90° domains were reoriented, which corresponds to ∼2% contribution to total polarization.

Polymerization reactions of α,α‘-bis(tetrahydrothiophenio)-p-xylene dichlorides with OH- in H2O have been studied kinetically. The reactions proceeded via the α-tetrahydrothiophenio-p-xylylene intermediates. Results of the H−D exchange experiments and kinetic studies reveal that the 1,6-elimination forming the intermediates proceeds reversibly via the ylide intermediate. The observed rate of disappearance of the intermediate was increased by the addition of OH-, tetrahydrothiophene, and S2O8 2- as well as by the photoirradiation with a tungsten lamp in the presence of Rose Bengal and was inhibited by TEMPO. However, the rate was found to be independent of ylide concentration. From these results, an elimination−free radical polymerization mechanism is proposed. The microscopic rate constants for each step of this mechanism were calculated from the change in the intermediate concentration with time. All of the rate data showed excellent correlations with the substituent constants in the Hammett plot.