A model of hierarchically interacting quantum anharmonic oscillators is considered. For this model, the sequence of abnormally normed fluctuations of the coordinate operator is shown to converge to a nontrivial thermodynamic limit when the model parameters satisfy certain conditions. This is a manifestation of the presence of a critical point for the model. Conditions on the parameters are also found which are sufficient to exclude critical points. 相似文献
We present the results from testing Monolithic Active Pixel Sensors of the detector ALPIDE (ALICE Pixel Detector). The purpose of these tests was to measure the pixel threshold and noise distributions in each of the four sectors of the detector, as well as the analysis of the hit maps produced by different radioactive sources. 相似文献
We give a sufficient condition for essential self-adjointness of symmetric operators associated with classical Dirichlet forms on Hilbert spaces. The condition implies a one-sided restriction on the derivatives for a suitable approximation of the drift coefficient but does not involve Lp or smoothness conditions on .Supported by the Alexander von Humboldt Foundation. 相似文献
Steady-state absorption spectra of poly-3-octylthiophene films in different oxidation states and differential cyclic voltabsorptograms of poly-3-octylthiophene films in 0.1 M LiClO4 solutions in acetonitrile are studied. Electron spectra of films demonstrate the following three absorption bands: a complex band with a pronounced maximum at λ = 450 nm, which corresponds to π → π* electron transitions in the reduced fragments of poly-3-octylthiophene films and two absorption bands (at λmax = 780 and λmax > 1100 nm), which correspond to the oxidized film fragments. It is concluded that two chemically and optically distinguishable oxidation products are formed during the polymer oxidation. 相似文献
The paper presents results of studying the electrochemical properties of poly-3,4-ethylenedioxythiophene films using the methods of cyclic voltammetry and faradaic impedance spectroscopy in acetonitrile and propylene carbonate solutions of different electrolytes: LiClO4, Bu4NBF4, Bu4NPF6. The effect of the film synthesis conditions, the nature of anion and solvent, and the supporting electrolyte concentration on the film redox capacitance is discussed. Main attention is paid to the comparison of values characterizing the redox capacitance of a poly-3,4-ethylenedioxythiophene film Clf (determined using the faradaic impedance method) and Ccv (determined using the cyclic voltammetry method) and the studies of their dependence on the varied experimental factors. The experimental Clf vs. E curves are analyzed using the relationships of a model of a uniform film. 相似文献
The present work has studied electrochemical and optical properties of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film electrodes drop-casted from commercial PEDOT:PSS aqueous dispersion with preliminary addition and without addition of LiClO4 electrolyte (further denoted as PEDOT:PSS/LiClO4 and PEDOT:PSS). Cyclic voltammetry measurements showed the significant increase in capacitance of PEDOT:PSS/LiClO4 film electrodes in comparison to PEDOT:PSS. Furthermore, the improved charge transport in PEDOT:PSS/LiClO4 films was demonstrated by electrochemical impedance spectra. In situ spectroelectrochemical measurements revealed that preliminary addition of LiClO4 into PEDOT:PSS aqueous dispersion allows to increase amount of free charge carriers (polaron and bipolaron states) in the resulting film during electrochemical oxidation in LiClO4 propylene carbonate solution. This increase was attributed to ion-induced charge screening between positively charged PEDOT and negatively charged PSS in polyelectrolyte structure, which was supported by structural investigations of both types of film electrodes by using FTIR, SEM, and XPS measurements. Charge screening results from a more open structure that allows conformational relaxation of PEDOT molecules during charge transport, which leads to partial separation of oppositely charged PSS and PEDOT molecules and facilitating the increase of electrochemical activity.