Quakes in solid quark stars

A starquake mechanism for pulsar glitches is developed in the solid quark star model. It is found that the general glitch natures (i.e., the glitch amplitudes and the time intervals) could be reproduced if solid quark matter, with high baryon density but low temperature, has properties of shear modulus mu(c) = 10(30-34) erg/cm(3) and critical stress sigma(c) = 10(18similar to24) erg/cm(3). The post-glitch behavior may represent a kind of damped oscillations. (C) 2004 Elsevier B.V. All rights reserved.

DISTRIBUTION FUNCTION OF A DRIFTING ELECTRON-GAS FOR GENERAL ENERGY-BAND STRUCTURES

The usual application of the Lei-Ting balance equation method for treating electron transport problems makes use of a Fermi distribution function for the electron motion relative to the center of mass. It is pointed out that this presumes the existence of a moving frame of reference that is dynamically equivalent to the rest frame of reference, and this is only true for electrons with a constant effective mass. The method is thus inapplicable to problems where electrons governed by a general energy-band dispersion E(k) are important (such as in miniband conduction). It is demonstrated that this difficulty can be overcome by introducing a distribution function for a drifting electron gas by maximizing the entropy subject to a prescribed average drift velocity. The distribution function reduces directly to the usual Fermi distribution for electron motion relative to the center of mass in the special case of E(k)=($) over bar h(2)\k\(2)/2m*. This maximum entropy treatment of a drifting electron gas provides a physically more direct as well as a more general basis for the application of the balance equation method.

Photoluminescence of ZnS clusters in zeolite-Y

Two obvious emissions are observed from the ZnS clusters encapsulated in zeolite-Y. The emission around 355 nm is sharp and weak, locating at the onset of the absorption edge. The band around 535 nm is broad, strong and Stokes-shifted. Both the two emissions shift to blue and their intensities firstly increase then decrease as the loading of ZnS in zeolite-Y or clusters size decreases. Through investigation, the former is attributed to the excitonic fluorescence, and the latter to the trapped luminescence from surface states. The cluster size-dependence of the luminescence may be explained qualitatively by considering both the carrier recombination and the nonradiative recombination rates. Four peaks appearing in the excitation spectra are assigned to the transitions of 1S-1S, 1S-1P, 1S-1D and surface state, respectively. The excitation spectra of the clusters do not coincide with their absorption spectra. The states splitted by quantum-size confinement are detected in the excitation spectra, but could not be differentiated in the optical absorption spectra due to inhomogeneous broadening. The size-dependence of the excitation spectra is similar to that of the absorption spectra. Both the excitation spectra of excitonic and of trapped emissions are similar, but change in relative intensity and shift in position are observed.

Photostimulated luminescence of silver clusters in zeolite-Y

Upon UV-irradiation at 254 nm, the photoluminescence of silver atoms in zeolite-Y decreases, meanwhile an absorption band shows up around 840 nm. By photostimulation at 840 nm, fluorescence of silver atoms is detected, which is called photostimulated luminescence, and the photoluminescence of silver atoms is increased slightly. These phenomena are attributed to the charge-transfer interaction between the zeolite framework and the entrapped silver atoms. (C) 1997 Published by Elsevier Science B.V.

Absorption spectra of Se-8-ring clusters in zeolite 5A

Samples with different weight ratio of Se to zeolite 5A (Se concentration) have been prepared by loading Se into the pores of zeolite 5A, and the measuerments of the absorption and Raman spectra have been carried out for the prepared samples. The measured absorption edges of the samples are close to the value for monoclinic Se containing Se-8-ring, suggesting the formation of Se-8-ring clusters(1) in the pores. The continuous and broadening features of the absorption spectra are interpreted by the strong electron-nucleus coupling in the Se-8-ring cluster. The absorption edges are red shifted with the increase of the Se concentration. It is tentatively attributed to two reasons. One is the existence of the double Se-8-ring cluster in the high Se concentration samples, and the other is that for the strong electron-nucleus coupling cluster, the absorption edge of the clusters system will be red shifted with the increase of the cluster concentration in the clusters system. A single broad band at about 262 cm(-1) is observed in the Raman spectra, which further supports the formation of Se-8-ring clusters. (C) 1997 Published by Elsevier Science S.A.

Thermoluminescence of CdS clusters in zeolite-Y

Thermoluminescence (TL) of CdS clusters encapsulated in zeolite-Y is reported for the first time. The TL of the clusters is much stronger than that of the bulk CdS and increases as the CdS loading decreases. This inverse dependence of TL intensity upon CdS loading is caused mainly by the size-effect of the clusters. All samples exhibit almost the same glow peak position and shape, indicating that traps or surface states are not sensitive to the cluster sizes.

New observation on the luminescence of CdS clusters in zeolite-Y

The excitation spectrum of CdS dusters in zeolite-Y is consistent with their absorption spectrum, both showing two absorption bands that are assigned to the Is-is and Is-lp transitions, respectively. A new emission at 400 nn is considered to be the recombination of the bounded excitons. The emission firstly increases then decreases with increasing cluster size or loading. The emission by excitation into the Is-is band is stronger and sharper than that by excitation into the Is-lp band. This phenomenon is attributed to the size inhomogeneity and the strong electron-phonon interaction of the dusters. Copyright (C) 1996 Elsevier Science Ltd

Absorption and Raman spectra of Se-8-ring clusters in zeolite 5A

Samples with different weight ratio of Se to zeolite 5A (Se composition) have been prepared by loading Se into the cages of zeolite 5A and the measurements of the absorption and Raman spectra have been carried out for the prepared samples. The measured absorption edges of the samples close and blue shifted to the value for monoclinic Se containing Se-8-ring, suggesting the formation of Se-8-ring clusters dagger in the cages. The continuous and broadening features of the absorption spectra are interpreted by the strong electron-phonon coupling in Se-8-ring clusters. The sample with high Se composition has a red shift of the absorption band edge relative to the samples with less Se composition. It is tentatively attributed to the reason that with different Se composition, single Se-8-ring clusters and double Se-8-ring clusters are formed in the cages of zeolite 5A. A single broad band at about 262 cm(-1) is observed in the Raman spectra, that gives the further support of the formation of Se-8-ring clusters. Copyright (C) 1996 Elsevier Science Ltd