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1.
Xiaofan Zhang 《中国物理 B》2022,31(11):114209-114209
We theoretically investigate the yield enhancement of elliptical high harmonics in the interaction of molecules with bicircular laser pulses by solving the time-dependent Schrödinger equation. It is shown that by adjusting the relative intensity ratio of the two bicircular field components in specific ranges the yield of the molecular high harmonics for the plateau and cutoff regions can be respectively enhanced. To analyze this enhancement phenomenon, we calculate the weights of the electron classical trajectories. Additionally, we also study the ellipticity distribution of harmonics for different intensity ratios. We find that these enhanced harmonics are elliptically polarized, which we mainly attribute to the recombination dipole moment of the major weighted trajectories. These enhanced elliptical extreme ultraviolet and soft x-ray radiations may serve as essential tools for exploring the ultrafast dynamics in magnetic materials and chiral media. 相似文献
2.
CuPc molecules adsorbed on Au(1 1 0)-(1 × 2): growth morphology and evolution of valence band states
Fabrizio Evangelista A. RuoccoValdis Corradini M.P. DonzelloCarlo Mariani Maria Grazia Betti 《Surface science》2003,531(2):123-130
We present the growth morphology, the long-range ordering, and the evolution of the valence band electronic states of ultrathin films of copper phthalocyanine (CuPc) deposited on the Au(1 1 0)-(1 × 2) reconstructed surface, as a function of the organic molecule coverage. The low energy electron diffraction patterns present a (5 × 3) reconstruction from the early adsorption stages. High-resolution UV photoelectron spectroscopy data show the disappearance of the Au surface states related to the (1 × 2) reconstruction, and the presence of new electronic features related to the molecule-substrate interaction and to the CuPc molecular states. The CuPc highest occupied molecular orbital gradually emerges in the valence band, while the interface electronic states are quenched, upon increasing the coverage. 相似文献
3.
In this paper, we discuss the detailed optical design of a beam line that is under construction on the synchrotron radiation source, Indus-1. Toroidal mirrors are used as pre-and post- focusing elements and a toroidal grating monochromator as a dispersing element. Using three interchangeable gratings, this monochromator will give, at a moderate resolution, a good throughput on the sample in the wavelength range 40 to 1000 Å. Effect of various parameters and their optimization on the resolution and throughput characteristics have been studied by ray tracing calculations, and presented. 相似文献
4.
Eu^2+:BaFCl光激励发光过程中紫外线的激发与漂白效应 总被引:1,自引:1,他引:0
通过改变紫外线的辐射照能量范围,研究了Eu^2+:BaFCl的光激励发光性质。发现紫外线能量大于Eu^2+的最低激发态能量及紫外线的能量小于Eu^2+最低激发态的能量两种情况下,光激励发光具有明显的差异,分析了产生差异的原因,给出了紫外线的辐照能量发生转时所对应的能级位置。 相似文献
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A. Hollnder J. E. Klemberg-Sapieha M. R. Wertheimer 《Journal of polymer science. Part A, Polymer chemistry》1995,33(12):2013-2025
The emission from low-pressure microwave plasmas in the vacuum-ultraviolet (VUV) region (λ < 200 nm) was investigated in order to use these plasmas as light sources for the study of the VUV photochemistry of polyethylene (PE) and polypropylene (PP) as part of the study of plasma-polymer interaction. These polymers, immersed in low-presure oxygen, were exposed to radiation with wavelengths down to 112 nm, the cut off of magnesium fluoride used as a window to separate the polymer specimen from the plasma light source. Total oxygen incorporation in the surface [O], and the formation of hydroxyl, carbonyl, and carboxyl groups were measured using XPS in combination with chemical derivatizations, particularly their dependence upon the radiation spectrum and the oxygen pressure around the sample. In most experiments the surface oxygen concentration [O] attained a constant value that appears to be related to the initial oxidation rate; this suggests a competition between oxygen incorporation and chain scission reactions, followed by the removal of volatile oxidation products. PE is usually oxidized to a higher level than PP, the latter appearing to be more susceptible to reaction with atomic oxygen than PE. A general initiation mechanism for the VUV experiments is proposed that allows us to explain the observed differences in behavior between PE and PP, and the results obtained under different irradiation conditions. The nature of oxidation products is in both cases very similar to what is observed after direct plasma treatment of the polymers. We conclude that short wavelength radiation contributes very appreciably to the observed surface modification effects during plasma treatment of PE and PP. © 1995 John Wiley & Sons, Inc. 相似文献
9.
Robert L Waterland Kerwin D Dobbs Amy M Rinehart Andrew E Feiring Robert C Wheland Bruce E Smart 《Journal of fluorine chemistry》2003,122(1):37-46
In its continuing quest for smaller length scales, the electronics industry plans to introduce 157 nm as the next lithographic wavelength. Accordingly, there is a pressing need to develop photoresists that are more transparent, and pellicles that are both more transparent and more durable. With the advent and popularization of time-dependent density functional theory (TD-DFT), we now have a practical quantum chemical method for calculating excitation energies and transition moments in the vacuum ultraviolet (VUV) which can greatly assist in the scouting of highly transparent materials. We have performed TD-DFT calculations for a broad variety of fluorinated molecules and we will report calculated VUV photoabsorption spectra for a large family of model fluorohexanes. These calculations, which span a range from 1-fluorohexane to CH3CF2CF2CF2CF2CH3, illustrate some of the principles one may use to design low absorption polymeric materials. 相似文献
10.
Spectral quantities of cyclopropane, cyclobutane, cyclohexane, and of several derivatives, have been calculated by a semiempirical all-valence electron SCF-CI MO method. In cyclopropane, HOMO is practically localized in the carbon-frame, and LVMO is purely so. In cyclobutane, these two MO's are based on C-H bonds, while cyclohexane holds an intermediate position. Despite the overall similarity-experimental and computed-of the spectra of these molecules, assignments are non-parallel. Like cyclopropane, cyclobutane can extend conjugation, but to a diminished degree; cyclohexane behaves in this respect like an acyclic alkane. An interpretation of this gradation, in terms of the nature of high-lying MO's, is proposed. 相似文献