A novel structure of ZnO nanorods on microsized ZnSe particles has been prepared through a chemical vapor deposition technique
using Zn and Se powders as the sources. The dimension of the nanorods can be controlled by adjusting the growth temperature,
time and the Zn : Se ratio. Through the investigation of the effects of synthesis time and Zn : Se ratio on the formation
of ZnO nanorods on ZnSe microparticles, it is proposed that the synthesis of the ZnO–ZnSe structures involves a two-stage
formation. The growth of ZnO nanorods can be described by the vapor–solid mechanism. The photoluminescence of the ZnO–ZnSe
structures has also been studied.
PACS 73.21.-b; 78.55.Et; 61.10.Nz; 61.46.+w; 68.65.-k 相似文献
Optical imaging provides an indispensable way to locate tumors in their early stages with high sensitivity and signal to background ratio. A heptamethine cyanine based fluorophore that emits both single photon near-infrared fluorescence and two-photon deep red fluorescence under physiological conditions was developed. Linear and nonlinear photophysical properties of this fluorophore were investigated and it demonstrated the capability to label lysosomes in cancer cells. The advantages of this fluorophore, including tolerable cytotoxicity, high fluorescence quantum yield, and the ability to emit both near-infrared single photon fluorescence and deep red two photon fluorescence in aqueous solution, give it potential to be used in intra-operatively optical image-guided tumor excision followed by two-photon fluorescence microscopy biopsy analysis after a single administration. 相似文献
The generality and usefulness ofM/G/C/C state dependent queueing models for modelling pedestrian traffic flows is explored in this paper. We demonstrate that the departure process and the reversed process of these generalizedM/G/C/C queues is a Poisson process and that the limiting distribution of the number of customers in the queue depends onG only through its mean. Consequently, the models developed in this paper are useful not only for the analysis of pedestrian traffic flows, but also for the design of the physical systems accommodating these flows. We demonstrate how theM/G/C/C state dependent model is incorporated into the modelling of large scale facilities where the blocking probabilities in the links of the network can be controlled. Finally, extensions of this work to queueing network applications where blocking cannot be controlled are also presented, and we examine an approximation technique based on the expansion method for incorporating theseM/G/C/C queues in series, merge, and splitting topologies of these networks. 相似文献
From quantum-chemical calculations of rotational g factor and new experimental measurements of strengths of lines in infrared spectra of vibration–rotational bands v′–0 in absorption, with 1≤v′≤4, of 12C16O, and from analysis of 16,947 frequencies and wave numbers assigned to pure rotational and vibration–rotational transitions
within electronic ground state X1Σ+, including new measurements of band 4–0 of 12C16O, we evaluate radial functions for potential energy and electric dipolar moment, the latter both in polynomial form and as
a rational function that has qualitatively correct behaviour under limiting conditions.
Received: 8 November 2001 / Accepted: 5 February 2002 / Published online: 14 August 2002 相似文献
ABSTRACT The synthesized ZnO NPs using durian rind in solution has shown maximum absorption at 355.5?nm with the bandgap of 3.33?eV, spectrophotometrically. SEM and TEM studies revealed that the shape of the synthesized ZnO NPs was spherical with an average size of 280 and 283?nm, respectively. However, DLS analysis of ZnO NPs revealed the average particle size of 456?d.nm. The presence of [100], [002], [101], [102], [110], [103], [200], [112] and [201] planes in XRD corroborate the formation of pure wurtzite structure of ZnO NPs. Synthesized ZnO NPs showed remarkable photocatalytic activity on degradation of methylene blue and sulfanilamide, antioxidant activity, considerable antimicrobial activity against Escherichia coli and Staphylococcus aureus, and considerable cytotoxic activity against brine shrimp. The sulfanilamide degradation was found to be 96.70%, under natural sunlight and in the presence of 0.1% ZnO NPs at pH 10 with a time of 3?h. The dye degradation was found to be 84% under sunlight in the presence of 0.01% ZnO NPs at pH 10 with a time of 40?min. The synthesized ZnO NPs may be explored furthermore in the fields of wastewater treatment, biomedicine, biosensor, and nanotechnology. 相似文献
By virtue of the electron‐donating and electron‐withdrawing properties of the thiazole ring, a new soluble rigid‐rod organometallic polymer containing electron‐donating and electron‐withdrawing trans‐[‐Pt‐(PBu3)2‐C≡C—R—C≡C—]n (R = bithiazolediyl) groups is prepared by CuI‐catalyzed dehydrohalogenation. The thermal properties and the optical absorption and photoluminescence spectra of the polymer are reported. The polymer is luminescent with a singlet emission peak at 539 nm and photoconducting in a single‐layer sandwich structure photocell. The optical gap of the polymer is reduced compared to that for the oligothienyl analogue. 相似文献
In recent years, optical vortex beams possessing orbital angular momentum have received much attention due to their potential for high‐capacity optical communications. This capability arises from the unbounded topological charges of orbital angular momentum (OAM) that provide infinite freedoms for encoding information. The two most common approaches for generating vortex beams are through fork diffraction gratings and spiral phase plates. While realization of conventional spiral phase plate requires complicated 3D fabrication, the emerging field of metasurfaces has provided a planar and facile solution for generating vortex beams of arbitrary orbit angular momentum. Among various types of metasurfaces, the geometric phase metasurface has shown great potential for robust control of light‐ and spin‐controlled wave propagation. Here, we realize a novel type of geometric metasurface fork grating that seamlessly combine the functionality of a metasurface phase plate for vortex‐beam generation, and that of a linear phase gradient metasurface for controlling the wave‐propagation direction. The metasurface fork grating is therefore capable of simultaneously controlling both the spin and the orbital angular momentum of light.