共查询到12条相似文献,搜索用时 0 毫秒
1.
利用不同加热机制产生的超热电子所导致的相干渡越辐射(CTR)在谐波分量强度比上的不同,给出了区分飞秒激光等离子体相互作用产生超热电子过程中的主要与次要加热机制的一种可能方法.得到了加热周期不同的加热机制所产生超热电子的比例与CTR谐波分量的二倍频和一倍频的强度比之间的具体关系式.如果在实验上测到此谐波分量强度比,就可以推出不同加热机制在加热过程中所起作用的大致比例关系.另外,CTR谐波分量的强度比还与超热电子的温度、实验上所使用靶的厚度有一定依赖关系,对此作了较为详细的讨论.
关键词:
相干渡越辐射
超热电子
加热机制 相似文献
2.
Valery A. Loiko Gennady I. Ruban Alexey D. Gruzdev Natalia V. Goncharova 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,102(1):73-84
The peripheral blood lymphocytes of normal individuals are investigated by methods of specialized light microscopy. Lymphocytes as a whole and T-cell subpopulation are considered. Lymphocyte structure is characterized with reference to polarizing scanning flow cytometry. The lymphocyte and lymphocyte nucleus shapes are analyzed. Linear correlation dependence between sizes of lymphocyte and its nucleus is indicated. A morphometric model of a lymphocyte is constructed using the obtained data. The findings can be used, for instance, as input parameters to solve the direct and inverse light-scattering problems of turbidimetry, nephelometry, and flow cytometry. 相似文献
3.
We report preliminary results of using a scanning probe microscope/laser combination to perform nanostructuring on insulator and metal surfaces in air. This technique enables processing of structures with a lateral resolution of approximately 10 nm. In this paper we present our last structuring results with both scanning tunnelling and scanning force microscopy. Some possible interaction mechanisms responsible for the structuring will be discussed. 相似文献
4.
Coronal sections of unfixed rat brain samples were prepared on a flat substrate in order to reveal hippocampal formation (CA1-4 pyramidal neurons) and adjacent neocortical white matter. We demonstrate the feasibility of using surface sensitive techniques such as time-of-flight secondary ion mass spectrometry (ToF-SIMS) and scanning probe microscopy (SPM) to probe lipid distribution, as well as the subcellular features of neurons. In the same anatomical areas, the phase shift image in SPM is especially useful in revealing the cross-section of subcellular structures. We show that the phase shift images reveal distinctive subcellular features and ion images of CN− and PO2− fragments from ToF-SIMS appear to define some of the subcellular features. 相似文献
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R. Ambigapathy C. Corbel P. Hautojärvi A. A. Manuel K. Saarinen 《Applied Physics A: Materials Science & Processing》1996,62(6):529-532
Two-Dimensional Angular Correlation of positron Annihilation Radiation (2D-ACAR) experiments have been performed on n-type GaAs. By combining these results with those from positron lifetime experiments, the momentum distribution of the arsenic vacancy in its neutral (V
aAs
0
) and negative (V
As
–
) charge states have been extracted. These distributions were all normalized to the respective positron lifetime that characterizes them. The first thing to be noticed is that the momentum distributions of the vacancies, as seen by the positron, are fairly isotropic and structureless. The distribution forV
As
0
is more peaked than that ofV
As
–
while the latter is more intense in the large momentum regions of the spectra. From this, it can be inferred that VA. has a smaller open volume thanV
As
0
A closer look at the momentum distribution of the vacancies reveals that they are not entirely isotropic, but, in fact, have a bulk-like component. Finally, the experimental results for bulk GaAs andV
As
–
compare well in a qualitative manner with the momentum distributions that result from an ab-initio molecular dynamics calculation. 相似文献
7.
Optical conductivity as a probe of a hidden Fermi-liquid behavior in BaFe_(1.904) Ni_(0.096) As_2 下载免费PDF全文
We measured the infrared reflectivity of BaFe1.904Ni0.096As2 single crystal from room temperature down to 20 K.Two Drude terms and a Lorentz term well describe the real part of the optical conductivity σ1(ω). We fit the reciprocal of static optical conductivity 1/σ1(0) by the power law ρ(T)=ρ0+ATnwith n=1.6. The broad Drude component exhibits an incoherent background with a T-independent scattering rate 1/τb, while the other narrow one reveals a T-quadratic scattering rate 1/τn, indicating a hidden Fermi-liquid behavior in BaFe1.904Ni0.096As2 compound. 相似文献
8.
Energy loss of a fast-electron beam due to the excitation of collective oscillation in hot plasma 下载免费PDF全文
Energy loss due to a fast-electron beam interacting with the hot plasma at a high density is analysed theoretically. By splitting the particle density fluctuations into the individual part due to the random thermal motion of the individual electrons and the collective part due to plasma-wave excitation, we are concerned with the collective interaction of the relativistic plasma electrons resulting from the Coulomb interactions. Consequently, we derive the frequency of the hot plasma and the "Debye length" with the modification of the relativistic effect. And finally we calculate the energy loss of a fast-electron beam due to the excitation of collective oscillation in the hot plasma. 相似文献
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This paper presents an original method of analyzing radiation loss from dielectric slab with random wall imperfections. The method is based on Maxwell’s equations under their covariant form written in a non-orthogonal coordinate system. The solution is found by using a perturbation method applied to the smooth surface problem. The statistical characteristics of the radiation intensity, the average value and the probability density function, are analytically determined. 相似文献
11.
Methylene blue (MB) was developed as a sensitive DNA probe for a comparative study of Cd2+, Pb2+ and Cr3+ ions binding with calf thymus DNA (ctDNA). The fluorescence intensity of the MB-ctDNA system increased dramatically when heavy metal ions (Cd2+, Pb2+ and Cr3+ ions) were added, which indicated that some of the bound MB molecules were released from the ctDNA base pairs. To compare the binding affinity of these three different heavy metal ions with ctDNA, the relationships between the fluorescence intensity of the MB-ctDNA-M (Metal ions) system and the concentration ratio of [M]/[DNA(p)] were investigated. The results showed that the order of the binding affinity of heavy metal ions with ctDNA had the following sequence: Cr3+> Cd2+>Pb2+. This order was further proved by the effects of heavy metal ions on the number of MB bound to ctDNA, the measurements of binding constants of these heavy metal ions to ctDNA, and the effects of heavy metal ions on the absorption of the MB-ctDNA system. In addition, the interaction mechanisms of Cd2+, Pb2+ and Cr3+ ions with ctDNA were also discussed in detail. These results indicated that their interaction mechanisms are related to the concentration ratios of heavy metal ions to DNA. 相似文献
12.
Massimo Tallarida Rakesh Sohal Dieter Schmeisser 《Superlattices and Microstructures》2006,40(4-6):393
Silicon is by far the most important material used in microelectronics, partly due to the excellent electronic properties of its native oxide (SiO2), but substitute semiconductors are constantly the matter of research. SiC is one of the most promising candidates, also because of the formation of SiO2 as native oxide. However, the SiO2/SiC interface has very poor electrical properties due to a very high density of interface states which reduce its functionality in MIS devices. We have studied the electronic properties of defects in the SiO2/Si and SiO2/SiC interfaces by means of XAS, XPS and resonant photoemission at the O 1s and the Si 2p edges, using silicon dioxide thermally grown with thicknesses below 10 nm. Our XAS data are in perfect agreement with literature; in addition, resonant photoemission reveals the resonant contributions of the individual valence states. For the main peaks in the valence band we find accordance between the resonant behaviour and the absorption spectra, except for the peaks at −15 eV binding energy, whose resonant photoemission spectra have extra features. One of them is present in both interfaces and is due to similar defects, while another one at lower photon energy is present only for the SiO2/SiC interface. This is related to a defect state which is not present at the SiO2/Si interface. 相似文献