排序方式: 共有43条查询结果,搜索用时 15 毫秒
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Guo J Baker GA Hillesheim PC Dai S Shaw RW Mahurin SM 《Physical chemistry chemical physics : PCCP》2011,13(27):12395-12398
In this work, we provide new experimental evidence for chain length-dependent self-aggregation in room temperature ionic liquids (RTILs) using fluorescence correlation spectroscopy (FCS). In studying a homologous series of N-alkyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide, [C(n)MPy][Tf(2)N] RTILs of varying alkyl chain length (n = 3, 4, 6, 8, and 10), biphasic rhodamine 6G solute diffusion dynamics were observed; both the fast and slow diffusion coefficients decreased with increasing alkyl chain length, with the relative contribution from slower diffusion increasing for longer-chain [C(n)MPy][Tf(2)N]. We propose that the biphasic diffusion dynamics originate from self-aggregation of the nonpolar alkyl chains in the cationic [C(n)MPy](+). 相似文献
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Shannon M. Mahurin Sumedh P. Surwade Marcos Crespo Sheng Dai 《Journal of Raman spectroscopy : JRS》2016,47(5):585-590
We report an in situ measurement of the interaction of an imidazolium‐based room temperature ionic liquid with both pure silver and a graphene‐over‐silver electrode under an applied electrochemical potential. At a negative applied potential, overall signal intensity increased indicating enhanced ionic liquid concentration at both silver and graphene electrodes. Vibrational modes associated with the imidazolium ring exhibited greater intensity enhancements and larger peak shifts compared with the anion indicating that the cation adsorbs with the ring and alkyl chain parallel to the electrode surface for both silver and graphene. In contrast to the silver, the surface enhanced Raman spectra of the ionic liquid near graphene showed shifts in the cation peaks even at no applied potential because of the strong π–π interaction between the ionic liquid and the graphene. Furthermore, the intensity of the graphene peak decreased in the presence of ionic liquid possibly due to the interaction between the ionic liquid and graphene. These results illustrate the effectiveness of surface‐enhanced Raman spectroscopy to investigate electrolyte interactions with graphene at the liquid/electrode interface. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Simple Zeros of the Riemann Zeta-Function 总被引:1,自引:0,他引:1
Assuming the Riemann Hypothesis, Montgomery showed by meansof his pair correlation method that at least two-thirds of thezeros of Riemann's zeta-function are simple. Later he and Taylorimproved this to 67.25 percent and, more recently, Cheer andGoldston increased the percentage to 67.2753. Here we proveby a new method that if the Riemann and Generalized LindelöofHypotheses hold, then at least 70.3704 percent of the zerosare simple and at least 84.5679 percent are distinct. Our methoduses mean value estimates for various functions defined by Dirichletseries sampled at the zeros of the Riemann zeta-function. 1991Mathematics Subject Classification: 11M26. 相似文献
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Santanu Roy Shobha Sharma Waruni V. Karunaratne Fei Wu Ruchi Gakhar Dmitry S. Maltsev Phillip Halstenberg Milinda Abeykoon Simerjeet K. Gill Yuanpeng Zhang Shannon M. Mahurin Sheng Dai Vyacheslav S. Bryantsev Claudio J. Margulis Alexander S. Ivanov 《Chemical science》2021,12(23):8026
Enhancing the solar energy storage and power delivery afforded by emerging molten salt-based technologies requires a fundamental understanding of the complex interplay between structure and dynamics of the ions in the high-temperature media. Here we report results from a comprehensive study integrating synchrotron X-ray scattering experiments, ab initio molecular dynamics simulations and rate theory concepts to investigate the behavior of dilute Cr3+ metal ions in a molten KCl–MgCl2 salt. Our analysis of experimental results assisted by a hybrid transition state-Marcus theory model reveals unexpected clustering of chromium species leading to the formation of persistent octahedral Cr–Cr dimers in the high-temperature low Cr3+ concentration melt. Furthermore, our integrated approach shows that dynamical processes in the molten salt system are primarily governed by the charge density of the constituent ions, with Cr3+ exhibiting the slowest short-time dynamics. These findings challenge several assumptions regarding specific ionic interactions and transport in molten salts, where aggregation of dilute species is not statistically expected, particularly at high temperature.Ion clustering of dilute chromium species was unexpectedly revealed in a high-temperature molten chloride salt, challenging several long-held assumptions regarding specific ionic interactions and transport in molten ionic media. 相似文献
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ac Conductivity measurements are carried out across the metal to insulator transition in NiAl0.7Cr0.7Fe0.6O4. The low frequency data is analyzed using Summerfield scaling theory for hopping conductivity. The exponent of the scaling
behavior has significantly different values in the conducting and insulating regimes. The hopping frequency and the zero frequency
conductivity are found to increase with temperature, slowly in the metallic regime and rapidly in the insulating regime. 相似文献