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941.
钱立冰 李鹏飞 靳博 靳定坤 宋光银 张琦 魏龙 牛犇 万成亮 周春林 Arnold Milenko Mü ller Max Dobeli 宋张勇 杨治虎 Reinhold Schuch 张红强 陈熙萌 《物理学报》2017,66(12):124101-124101
采用新的具有常数锥角的玻璃锥管,并对玻璃锥管进行了外表面导电屏蔽,通过对电子穿越玻璃锥管的二维角分布随时间演化的观测,研究了低能电子与玻璃管相互作用的机制.发现电子穿越完全放电的玻璃锥管时穿透率先下降后平稳,整个过程中角分布中心发生微小移动,但角分布的半高宽几乎保持不变.这与我们之前发表的工作(2016 Acta Phys.Sin.65 204103)不同,这是由于对玻璃锥管进行外表面导电屏蔽会阻止外界不确定的快速充放电的影响,并形成了新的稳定放电通道,有利于实现电子的稳定穿透.电子的穿透率随倾角呈类似矩形的分布,透射电子的角分布中心伴随倾角的变化而移动,其穿透所容许的倾角与几何穿透一致. 相似文献
942.
Sina Brockmann Thuro Arnold Bernd Schweder Gert Bernhard 《Journal of fluorescence》2010,20(4):943-951
Bacteria in acidophilic biofilm communities, i.e. acid streamers and snottites, obtained from a subsurface mine in Königstein were visualized by fluorescence microscopy using four new fluorescent dyes (DY-601XL, V07-04118, V07-04146, DY-613). The pH of the bulk solution in which these bacteria thrive was pH 2.6 to 2.9. The new fluorescent dyes were all able to clearly stain and microscopically visualize in-situ the bacteria within the biofilm community without changing pH or background ion concentration. The commonly used fluorescent dyes DAPI and SYTO 59 were also applied for comparison. Both dyes, however, were not able to visualize any bacteria in-situ, since they were not stable under the very acid conditions. In addition, dye V07-04118 and dye DY-613 also possess the ability to stain larger cells which were presumably eukaryotic origin and may be attributed to yeast cells or amoeba-like cells. PCR analyses have shown that the dominant bacterial species in these acidophilic biofilm communities was a gram negative bacterium of the species Ferrovum myxofaciens. The presented four new dyes are ideal for in-situ investigations of microorganisms occurring in very acid conditions, e.g. in acidophilic biofilm communities when in parallel information on pH sensitive incorporated fluorescent heavy metals should be acquired. 相似文献
943.
Kyle A. Mandla Michael L. Neville Curtis E. Moore Arnold L. Rheingold Joshua S. Figueroa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(43):15473-15477
Relative to other cyclic poly‐phosphorus species (that is, cyclo‐Pn), the planar cyclo‐P4 group is unique in its requirement of two additional electrons to achieve aromaticity. These electrons are supplied from one or more metal centers. However, the degree of charge transfer is dependent on the nature of the metal fragment. Unique examples of dianionic mononuclear η4‐P4 complexes are presented that can be viewed as the simple coordination of the [cyclo‐P4]2? dianion to a neutral metal fragment. Treatment of the neutral, molybdenum cyclo‐P4 complexes Mo(η4‐P4)I2(CO)(CNArDipp2)2 and Mo(η4‐P4)(CO)2(CNArDipp2)2 with KC8 produces the dianionic, three‐legged piano stool complexes, [Mo(η4‐P4)(CO)(CNArDipp2)2]2? and [Mo(η4‐P4)(CO)2(CNArDipp2)]2?, respectively. Structural, spectroscopic, and computational studies reveal a similarity to the classic η6‐benzene complex (η6‐C6H6)Mo(CO)3 regarding the metal‐center valence state and electronic population of the planar‐cyclic ligand π system. 相似文献
944.
Mark D. Straub Jennifer Leduc Michael Frank Aida Raauf Trevor D. Lohrey Stefan G. Minasian Sanjay Mathur John Arnold 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(17):5805-5809
Homoleptic uranium(IV) amidate complexes have been synthesized and applied as single‐source molecular precursors for the chemical vapor deposition of UO2 thin films. These precursors decompose by alkene elimination to give highly crystalline phase‐pure UO2 films with an unusual branched heterostructure. 相似文献
945.
946.
We investigate a system consisting of two like-charged infinitely long rods and neutralizing counterions at low temperatures,
using both analytic theory and simulations. With some reasonable approximations we can analytically solve for several ground-state
structures of the model, starting with states where all counterions are lined up in the gap between the rods, over planar
configurations, where the counterions are divided up into a fraction which resides between the rods, and counterions which
are located on the outer surfaces, up to configurations which cover the full rod surfaces. Using parallel tempering simulations,
we are able to study the system over a wide range of temperatures. At low temperatures we find good agreement with our T = 0 results. At higher temperatures, the strong coupling (SC) theory delivers qualitatively better results. We furthermore
demonstrate that for the SC theory and our ground-state approximations to yield quantitative agreement, three parameters are
required to be large, the strong-coupling parameter Ξ, the Rouzina-Bloomfield parameter, and the ratio of the average distance
of the counterions to the radius of the rods. In the case of the latter ratio being small, our T = 0 results show better agreement with the simulation data at very low temperatures. 相似文献
947.
Alexandre Mermillod-Blondin Euan McLeod Craig B. Arnold 《Applied Physics A: Materials Science & Processing》2008,93(1):231-234
The ability to dynamically shape the spatial intensity profile of an incident laser beam enables new ways to modify and structure
surfaces through pulsed laser processing. Here we describe a method to generate doughnut-shaped beams from an input Gaussian
source using a tunable acoustic gradient index (TAG) lens. The TAG lens is capable of modulating between focused beams and
annular rings of variable size, using sinusoidal driving frequencies. Laser micromachining is accomplished by synchronizing
the TAG lens to a 355 nm pulsed nanosecond laser. Results in polyimide demonstrate the ability to generate adjacent surface
features with different shapes and sizes. 相似文献
948.
Nikita Arnold 《Applied Physics A: Materials Science & Processing》2008,92(4):1005-1012
Calculations of the field distribution in colloidal SiO2 microspheres are presented. Two cases are considered: small particles on a Si substrate irradiated by the 266 nm light, and
larger ones, covered with a gold film and irradiated at 800 nm. Substrate, neighboring spheres and sputtered metal overlayer
all significantly modify the field pattern and magnitude. Reflected light is focused inside the spheres, which may lead to
their damage. The results can be useful in the analysis of microspheres-assisted nano-patterning. 相似文献
949.
E. Quinquaud und C. Arnold 《Fresenius' Journal of Analytical Chemistry》1882,21(1):605-608
Ohne Zusammenfassung 相似文献
950.
Delanson R. Crist Arnold P. Borsetti Mary Beth Kass 《Journal of heterocyclic chemistry》1981,18(5):991-995
The polarographic behavior of a series of N,N-dimethyl-2-arylaziridinium fluorosulfonates was investigated as another example of ring-opening reactions of this important class of compounds. Half-wave potentials showed that in water reduction was facilitated by electron-donating groups. This unusual result was explained in terms of electron transfer to an aminocarbonium ion-like species. In methylene chloride, however, two one-electron waves were observed, with the first showing a normal substituent effect (? = 0.17 ± 0.03 V). This result indicated direct electron transfer to the aziridinium ion itself to form a radical species which was detected by cyclic voltammetry. Reasons for the change in mechanism are presented, and E1/2 values for selected aziridinium salts illustrate the importance of steric effects on the reduction process. 相似文献