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Theoretical study of (e,2e) triple differential cross sections of pyrimidine and tetrahydrofurfuryl alcohol molecules using multi-center distorted-wave method 下载免费PDF全文
We report theoretical studies of electron impact triple differential cross sections of two bio-molecules,pyrimidine and tetrahydrofurfuryl alcohol,in the coplanar asymmetric kinematic conditions with the impact energy of 250 eV and ejected electron energy of 20 eV at three scattering angles of-5°,-10°,and-15°.Present multi-center distorted-wave method well describes the experimental data,which was obtained by performing(e,2e)experiment.The calculations show that the secondary electron produced by the primary impact electron is strongly influenced by the molecular ionic multi-center potential,which must be considered when the low energy electron interacts with DNA analogues. 相似文献
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An ultra-high vacuum(UHV) compatible electron spectrometer employing a double toroidal analyzer has been developed. It is designed to be combined with a custom-made scanning tunneling microscope(STM) to study the spatially localized electron energy spectrum on a surface. A tip–sample system composed of a piezo-driven field-emission tungsten tip and a sample of highly ordered pyrolytic graphite(HOPG) is employed to test the performance of the spectrometer.Two-dimensional images of the energy-resolved and angle-dispersed electrons backscattered from the surface of HOPG are obtained, the performance is optimized and the spectrometer is calibrated. A complete electron energy loss spectrum covering the elastic peak to the secondary electron peaks for the HOPG surface, acquired at a tip voltage of-140 V and a sample current of 0.5 pA, is presented, demonstrating the viability of the spectrometer. 相似文献
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介绍了量子计算机的最新发展状况。对实现量子计算机的各种实验方法作了简介和比较。特别是详细介绍了最近Kane提出的一种方案,并提出了一种新的用扫描隧道显微镜实现基于单原子的量子计算机方案。 相似文献
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The experimental relationship between width and amplitude of the non-destructive threshold pulse for Pt tip of a scanning tunneling microscope (STM) on graphite surface have been studied strictly and systematically in a wide range of pulse width for the first time. The threshold curve of amplitude versus width indicates that the amplitude of threshold pulse will increase with the decrease of the pulse width. A more rigorous explanation is suggested to interpret the dependence of threshold pulse amplitude on width. Fitted with the experimental data,a new empirical formula is given, extrapolated from which the threshold pulse amplitude will rise to 50 V when the pulse width decreases to 10ns. 相似文献
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Electron Momentum Distributions for 4a1 Orbitals of CFxCl4-x in Low Momentum Region: a Possible Evidence of Molecular Geometry Distortion 下载免费PDF全文
由于低动量区域理论和实验的严重差异,重新分析了系列氟利昂分子CF3Cl、CF2Cl2和CFCl3 (CFxCl4-x, x=1~3)的4a1轨道的电子动量分布. 利用分子离子的平衡几何构型计算得到的动量分布很大地改善了,与实验数据之间的吻合,这一结果表明在p<0.5 a.u.区域实验观测到的偏高的动量分布值可能是电离瞬间分子构型的扭曲带来的. 进一步的分 相似文献
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建立起一套工作于真空环境下的基于脉冲电压扫描隧道显微镜(STM)的单原子识别预研究装置.该装王主要由脉冲发生器、真空系统和STM系统三部分组成,能够在5×10-5Pa的真空环境下进行快脉冲STM实验.利用此装置,进行了单个快脉冲诱导的石墨表面超大周期结构的脉冲实验以及脉冲偏压不破坏STM针尖和样品表面的阈值实验. 相似文献
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<正>电子与样品的非弹性散射过程是电子能谱技术的基础。然而非弹性散射电子通常只占极少的比例,大多数电子是没有能量损失的弹性散射电子。最新的实验研究发现,银纳米结构激发出的局域等离激元场可以导致非线性的电子散射现象,使得非弹性电子的强度显著增强。这一新的发现未来可以用于研究吸附在金属纳米结构上的原子、分子,非线性电子散射过程会大大提高信号 相似文献
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