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Photophoretic force measurement on microparticles in binary complex plasmas
摘要： This article presents a method to measure the photophoretic force on microparticles in complex plasmas. A laser heating setup is used to increase the kinetic temperatures of binary mixtures composed of melamine-formaldehyde (MF) and silica (SiO2) particles. The temperature gain of both particle species due to the additional thermal reservoir is compared to a laser force model. Contributions of radiation pressure and photophoretic forces are determined through a variation of neutral gas pressure and application of Lorenz-Mie theory. The photophoretic force is found to be significant for MF particles at typical conditions in complex plasma experiments.
关键词： photophoretic force,microparticles,radiation pressure,complex plasmas,Lorenz-Mie theory,binary mixtures,laser heating
更新于2025-09-23 15:22:29
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Understanding the Microscopic Behavior of Binary Mixtures of Ionic Liquids Through Various Spectroscopic Techniques
摘要： In recent times it has been shown that certain binary mixture of pure ionic liquids having appropriate chemical composition can behave like a new chemical entity. However, current knowledge about the microscopic behavior of these interesting systems is rather limited. The present study is undertaken with an objective to understand the microscopic behavior in terms of intermolecular interaction, structure and dynamics of these systems. In the present study, few (IL+IL) mixtures are chosen with a common cation and a variation of anion. The investigations are also carried out by taking individual pure ILs so that the difference in behavior between pure IL and (IL+IL) mixtures are understood. Initially the systems have been investigated by studying the thermophysical properties of the concerned mixtures. Synergistic effect between combining pure ILs through photochromism has also been studied. These mixtures have been investigated further through steady state and time resolved fluorescence spectroscopy, electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR) and fluorescence correlation spectroscopy (FCS). Interestingly, time-resolved fluorescence data also pointed out that (IL+IL) mixtures are not only spatially heterogeneous but they are dynamically heterogeneous too. EPR measurements have suggested that the micro-polarity (ET(30)) of (IL+IL) mixture is close to aliphatic polyalcohol. Measurements of translational diffusion coefficients of the diffusing species through NMR and FCS studies have provided idea about the nano-structural organization within (IL+IL) binary mixtures. The analysis of data essentially reveals that the mixtures of ILs that are used in the current study do not behave like a non-ideal solution. The behavior of the IL mixtures is observed to be more like quasi-ideal type.
关键词： thermophysical properties,binary mixtures,EPR,FCS,fluorescence spectroscopy,NMR,Ionic liquids,photochromism,spectroscopic techniques
更新于2025-09-23 15:21:01
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Tracking small heterogeneity in binary mixtures of aliphatic and aromatic hydrocarbons: NIR spectroscopic, 2DCOS and MCR-ALS studies
摘要： To our best knowledge, this is the ?rst spectroscopic study of small heterogeneity at a molecular level in binary mixtures of aliphatic and aromatic hydrocarbons. The composition-dependent spectra of benzene/toluene, benzene/n hexane, benzene/cyclohexane, n hexane/n heptane and n hexane/cyclohexane mixtures were recorded by NIR transmission technique in the whole range of mole fractions. A comprehensive exploration of the experimental data was performed by two-dimensional correlation analysis (2DCOS) and chemometric methods. In addition, we calculated excess NIR molar absorption spectra and parameter of ER, which allows for comparison of the degree of deviation from ideality for various mixtures. Our results reveal that all studied mixtures deviate from the ideal mixture. The extent of these deviations is small for the mixtures were both components are aromatic or aliphatic and increases for aromatic/aliphatic mixtures. In addition, molecular shapes have an important effect on the degree of deviation from the ideal mixture. As expected, benzene/n hexane is the most non-ideal mixture, while behavior of n hexane/n heptane and benzene/toluene mixtures is close to the ideal one. Our results suggest that in the mixtures with the largest deviations from ideality are present homoclusters of both components and heteroclusters. The heteroclusters exist in the whole range of compositions, while the homoclusters appears above a certain concentration limit. If both components of the mixture are similar, the molecules with equal probability form the homo- and heteroclusters. In the case of unlike components, the molecules prefer to form the homoclusters. The homoclusters of both components in the mixture are similar as those observed in bulk constituents. This means that deviation from the ideal mixture results from presence of the heteroclusters.
关键词： Aliphatic/aromatic hydrocarbons,NIR,Clustering,MCR-ALS,Binary mixtures,2DCOS,Chemometrics,Excess absorption spectra,Microheterogeneity
更新于2025-09-19 17:15:36