Journal of Physical Chemistry C
·
2018
·
IF 4.484
Fengjiao Chen,Guoyong Fang,Zhipeng Yan,Yuexiao Pan,Jianbo Liu,Lin Wang
The cation structural changes of two 1-butyl-3-methylimidazolium halides, [BMIM]Cl and [BMIM]Br, are investigated by in situ Raman spectroscopy, infrared spectroscopy, and synchrotron X-ray diffraction as a function of hydrostatic pressure. The [BMIM]+ cations of [BMIM]Cl take the TT conformation under ambient conditions, undergo significant changes at 3.4 GPa, which is related to the potential formations of some new cation conformations, and take another conformation from 6.8 to 35.6 GPa. Correspondingly, crystalline [BMIM]Cl has a structure transition at 3.4 GPa, originating directly from the cation conformational changes. The [BMIM]+ cations totally transform into the GT conformer, if the diamond anvil cell-loaded sample is treated at 423 K for 12 h in a furnace before being cooled down to room temperature. It is the first time to observe the complete conformational transition from one conformer (TT) to another (GT) for the [BMIM]+ salts in experiments. The cations preserve the GT conformation as pressure reaches 44.6 GPa for heat-treated [BMIM]Cl. As a comparison, without and with the heat treatment, the [BMIM]+ cations of [BMIM]Br keep the GT conformation at high pressures up to 29.6 GPa, as it is a relatively stable state. Moreover, a notable photoluminescence emerges at high pressures over 20.0 GPa and is maintained in the decompression process, as a result of the pressure-induced polymerization of a small portion of the [BMIM]+ cations.
研究领域:
物理化学
·
材料科学
·
高压物理
·
离子液体
·
光谱学
✓ 已验证
DOI
高影响因子
ACS Omega
·
2020
·
IF 2.87
Hengyi Li,Kaikai Zheng,Jingfa Yang,Jiang Zhao
The diffusion of molecules and particles inside the aqueous suspension of soft colloids (polymer microgels) is investigated using variable length scale fluorescence correlation spectroscopy (VLS-FCS). Carbopol 940 is chosen as the model matrix system, and two factors affecting diffusion are investigated: the spatial hindrance and the diffusant–matrix interaction. By studying diffusion of molecules and particles with different sizes inside the suspension, VLS-FCS reveals the restricted motion at a short length scale, that is, in the gaps between the microgels, and normal diffusion at a larger length scale. The information on the gap’s length scale is also accessed. On the other hand, by tuning the pH value, the diffusant–matrix electrostatic attraction is adjusted and the results expose a short-time fast diffusion of probe molecules inside the gaps and a long-time restricted diffusion because of trapping inside the microgels. It is proved that VLS-FCS is a powerful method, investigating anomalous diffusion at different length scales and it is a promising approach to investigate diffusion in complex soft matter systems.
研究领域:
软物质物理
·
物理化学
·
胶体科学
·
生物物理学
·
光谱学
✓ 已验证
DOI
高影响因子
NANO LETTERS
·
2022
·
IF 12.262
Jia-Min Lai,Muhammad Umair Farooq,Yu-Jia Sun,Ping-Heng Tan,Jun Zhang
The multiphonon process plays an essential role in understanding electron–phonon coupling, which significantly influences the optical and transport properties of solids. Multiphonon processes have been observed in many materials, but how to distinguish them directly by their spectral characteristics remains controversial. Here, we report high-order Raman scattering up to 10 orders and hot luminescence involving 11 orders of phonons in Mn-doped ZnO nanowires by selecting the excitation energy. Our results show that the intensity distribution of high-order Raman scattering obeys an exponential decrease as the order number increases, while hot luminescence is fitted with a Poisson distribution with a resonance factor. Their linewidth and frequency can be well explained by two different transition models. Our work provides a paradigm for understanding the multiphonon-involved decay process of an excited state and may inspire studies of the statistical characteristics of excited state decay.
研究领域:
凝聚态物理
·
材料科学
·
光谱学
·
纳米材料
·
固体物理
✓ 已验证
DOI
高影响因子
JOURNAL OF PHYSICAL CHEMISTRY A
·
2011
·
IF 2.732
Min Xie,Yajing Qi,Yongjun Hu
2-Phenylethylamine (PEA) is the simplest aromatic amine neurotransmitter, as well as one of the most important. In this work, the conformational equilibrium and hydrogen bonding in liquid PEA were studied by means of Raman spectroscopy and theoretical calculations (DFT/MP2). By changing the orientation of the ethyl and the NH2 group, nine possible conformers of PEA were found, including four degenerate conformers. Comparison of the experimental Raman spectra of liquid PEA and the calculated Raman spectra of the five typical conformers in selected regions (550−800 and 1250−1500 cm−1) revealed that the five conformers can coexist in conformational equilibrium in the liquid. The NH2 stretching mode of the liquid is red-shifted by ca. 30 cm−1 relative to that of an isolated PEA molecule (measured previously), implying that intermolecular N−H···N hydrogen bonds play an important role in liquid PEA. The relative intensity of the Raman band at 762 cm−1 was found to increase with increasing temperature, indicating that the anti conformer might be favorable in liquid PEA at room temperature. The blue shift of the band for the bonded N−H stretch with increasing temperature also provides evidence of the existence of intermolecular N−H···N hydrogen bonds.
研究领域:
物理化学
·
光谱学
·
计算化学
·
分子结构
✓ 已验证
DOI
高影响因子
MACROMOLECULES
·
2014
·
IF 5.927
Bo Zhang,Hui Tang,Peiyi Wu
Dynamic thermal phase transition behavior of a thermoresponsive copolymer P(MEO2MA-co-PEGMA2080) synthesized by ATRP random copolymerization of 2-(2-methoxyethoxy)ethyl methacrylate(MEO2MA, Mn = 188 g/mol) and poly(ethylene glycol) methyl ether methacrylate (PEGMA, Mn= 2080 g/mol) in D2O was studied by means of infrared spectroscopy in combination with two-dimensional correlation analysis (2Dcos). Because of the absence of strong intermolecular hydrogen bonding interactions between polymer chains and the amphiphilic property of PEGMA2080 with long ethylene glycol segments, this copolymer exhibited an unusual thermally induced multistep aggregation process. In general, the change of hydrophilic side chain takes place before carbonyl groups and backbones during the whole process and thus the driving force of this phase transition process of P(MEO2MA-co-PEGMA2080) should be hydration changes of side chains. 2Dcos was finally employed to discern the sequence order of all the group motions during heating process in different temperature regions. It is concluded that during the phase transition P(MEO2MA-co-PEGMA2080) chains successively experience “unimers–clusters–micelles– aggregates” four consecutive conformation changes.
研究领域:
高分子科学
·
材料化学
·
物理化学
·
智能材料
·
光谱学
✓ 已验证
DOI
高影响因子
INORGANIC CHEMISTRY
·
2021
·
IF 5.165
Jingbo Yu,Lili Hu,Jinjun Ren
Rare earth ion-doped oxyfluoride glasses in the system 50SiO2–(50 – x)PbO–xPbF2–mLa2O3–nEr2O3 were prepared by the melt-quenching method. PbF2 and LaF3 were selectively crystallized by subsequent heat treatment in these glasses. The promotion and suppression effects of La3+ ions on the crystallization of PbF2 were observed in this selective crystallization. We used advanced solid-state nuclear magnetic resonance (NMR) and X-ray diffraction techniques to probe the structural evolution in the atomic level during these crystallizations. Based on the in-depth structure study, it can be inferred that both the different effects arise from the stronger ability of La3+ ions in attracting F– ions than that of Pb2+ ions. Intensive upconversion visible luminescence was observed in these glasses. The NMR and the upconversion luminescence results imply that most Er3+ ions are dissolved in the LaF3 crystal rather than in the PbF2 crystal and the glass phases even when the content of the LaF3 crystal is as small as less than 1 mol %. The results show that the past expectation that rare earth ions are homogenously incorporated into bivalent metal fluoride crystals might not be right and prove the validity of the strategy that multiple rare earth ions are codoped to increase the upconversion luminescent efficiency.
研究领域:
材料科学
·
固态化学
·
光谱学
·
光学材料
·
玻璃与陶瓷
✓ 已验证
DOI
高影响因子
JOURNAL OF PHYSICAL CHEMISTRY B
·
2011
·
IF 3.603
Shengtong Sun,Peiyi Wu
IR spectroscopy in combination with two-dimensional correlation spectroscopy (2DCOS) and the perturbation correlation moving window (PCMW) technique is employed to illustrate the dynamic hydration behavior of poly(N-vinylcaprolactam) (PVCL) in water, which exhibits a typical type I continuous lower critical solution temperature (LCST) behavior. PCMW easily determined the transition temperature to be ca. 43.5 °C during heating and ca. 42.5 °C during cooling and the transition temperature range to be 39.5–45 °C. On the other hand, 2DCOS was used to discern the sequence order of different species in PVCL and concluded that hydrogen bonding transformation predominates at the first stage below LCST while hydrophobic interaction predominates at the second stage above LCST. In combination with molecular dynamics simulation results, we find that there exists a distribution gradient of water molecules in PVCL mesoglobules ranging from a hydrophobic core to a hydrophilic surface. Due to the absence of self-associated hydrogen bonds and topological constraints, PVCL mesoglobules would form a “sponge-like” structure which can further continuously expel water molecules upon increasing temperature, while poly(N-isopropylacrylamide) (PNIPAM) with self-associated hydrogen bonds forms mesoglobules with a “cotton-ball-like” structure without an apparent distribution gradient of water molecules and does not change much upon increasing temperature.
研究领域:
高分子科学
·
物理化学
·
光谱学
·
温敏性聚合物
·
软物质物理
✓ 已验证
DOI
高影响因子
ACS Applied Bio Materials
·
2018
·
IF 0
Zhong Yu,Zhongbo Zhou,Guocheng Huang,Xing Zheng,Linjie Wu,Shanshan Zhao,Fangang Meng
In-depth understandings of the interactions between NaOCl and foulants (e.g., alginate) at a molecular level can provide a deeper insight into the optimization of chemical cleaning. In this study, two-dimensional Fourier transform infrared correlation spectroscopic (2D-FTIR-COS) analysis was used to probe the hypochlorite oxidation of alginate at normal wastewater treatment operating pH (i.e., 6, 7, and 8). The 2D-FTIR-COS characterization indicated that the groups in alginate were degraded by NaOCl in a similar sequence at all investigated pHs: carboxylate groups (−COOH at pH 6 and 7) > C–O–C bonds, C–O bonds of uronic acids > C–O–C bonds. The results also showed that the presence of hemiacetals, which are formed by uronic acids, can protect alginate chains from oxidation during their initial exposure to NaOCl (30 min) and thus maintain alginate at a constant molecular size. Additionally, the rupture of C–O–C bonds resulting from initial oxidation (30 min) increased the viscosity of alginate solution because of the decreased stiffness of alginate chains and the rise of stronger intermolecular junctions. Long-term exposure to NaOCl (480 min) largely degraded uronic acids and the C–O–C bonds of alginate molecules, leading to decreases in molecular weight and viscosity at pH 6 and 7. However, because of the low degree of oxidation at pH 8, molecular weight and viscosity of alginates were slightly changed after long-term exposure (480 min) to NaOCl. Our results imply that the partial oxidation of alginate during hypochlorite scavenging enhanced its fouling propensity, which could have a potential implication for the implementation of chemical cleaning.
研究领域:
环境科学
·
膜技术
·
分析化学
·
水处理
·
光谱学
✓ 已验证
DOI
ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2011
·
IF 4.827
Dawei Li,Lulu Qu,Wenlei Zhai,Jinqun Xue,John S. Fossey,Yitao Long
A novel facile method for on-site detection of substituted aromatic pollutants in water using thin layer chromatography (TLC) combined with surface-enhanced Raman spectroscopy (SERS) was explored. Various substituted aromatics in polluted water were separated by a convenient TLC protocol and then detected using a portable Raman spectrometer with the prepared silver colloids serving as SERS-active substrates. The effects of operating conditions on detection efficacy were evaluated, and the application of TLC−SERS to on-site detection of artificial and real-life samples of aromatics/polluted water was systematically investigated. It was shown that commercially available Si 60-F254 TLC plates were suitable for separation and displayed low SERS background and good separation efficiency, 2 mM silver colloids, 20 mM NaCl (working as aggregating agent), 40 mW laser power, and 50 s intergration time were appropriate for the detection regime. Furthermore, qualitative and quantitative detection of most of substituted aromatic pollutants was found to be readily accomplished using the developed TLC−SERS technique, which compared well with GC−MS in terms of identification ability and detection accuracy, and a limit of detection (LOD) less than 0.2 ppm (even at ppb level for some analytes) could be achieved under optimal conditions. The results reveal that the presented convenient method could be used for the effective separation and detection of the substituted aromatic pollutants of water on site, thus reducing possible influences of sample transportation and contamination while shortening the overall analysis time for emergency and routine monitoring of the substituted aromatics/polluted water.
研究领域:
环境监测
·
分析化学
·
水质分析
·
光谱学
·
污染物检测
✓ 已验证
DOI
高影响因子
JOURNAL OF PHYSICAL CHEMISTRY B
·
2015
·
IF 3.302
Yuneng Shen,Tianmin Wu,Bo Jiang,Ganghua Deng,Jiebo Li,Hailong Chen,Xunmin Guo,Chuanqi Ge,Yajing Chen,Jieya Hong,Xueming Yang,Kaijun Yuan,Wei Zhuang,Junrong Zheng
In this work, MD simulations with two different force fields, vibrational energy relaxation and resonant energy transfer experiments, and neutron scattering data are used to investigate ion pairing and clustering in a series of GdmSCN aqueous solutions. The MD simulations reproduce the major features of neutron scattering experimental data very well. Although no information about ion pairing or clustering can be obtained from the neutron scattering data, MD calculations clearly demonstrate that substantial amounts of ion pairs and small ion clusters (subnanometers to a few nanometers) do exist in the solutions of concentrations 0.5 M*, 3 M*, and 5 M* (M* denotes mole of GdmSCN per 55.55 mole of water). Vibrational relaxation experiments suggest that significant amounts of ion pairs form in the solutions. Experiments measuring the resonant energy transfers among the thiocyanate anions in the solutions suggest that the ions form clusters and in the clusters the average anion distance is 5.6 Å (5.4 Å) in the 3 M* (5 M*) Gdm–DSCN/D2O solution.
研究领域:
物理化学
·
化学物理
·
溶液化学
·
分子动力学
·
光谱学
✓ 已验证
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2019
·
IF 3.131
Yanqi Gu,Shayu Li,Yuehong Xu,Jiaguang Han,Miao Gu,Zhipeng Cai,Yan lv,Guoxin Xie,Tianbao Ma,Jianbin Luo
The influence of an external magnetic field on the picosecond network dynamics of the salt (KCl) solution is investigated by terahertz time-domain spectroscopy. Because hydration changes the motions of water molecules clusters, we test hydration by measuring the change of dielectric loss caused by the slow relaxation of water molecules clusters. We find experimentally that the magnetic field enhances the number of water molecules involved in hydration and the radius of dynamic hydration layer in salt solutions. However, with the increasing concentration, there is a downward in the hydration enhancement per equivalent. Meanwhile, the simulated results show the number of water molecules in hydration layers increases which is consistent with our experimental results. Besides, the simulation reveals that external magnetic field mainly affects the second hydration layer and the stability of water molecules network in hydration layer is enhanced with external magnetic field .
研究领域:
物理化学
·
生物物理
·
分子生物学
·
光谱学
·
溶液化学
✓ 已验证
DOI
高影响因子
JOURNAL OF LUMINESCENCE
·
2013
·
IF 2.144
XiaoDan Zeng,Lin Zhu,FuSheng Zhang,LiYun Feng
The interaction of bovine serum with leucomalachite green (LMG) was investigated by spectroscopic methods . LMG was found to quench the intrinsic fluorescence of BSA by dynamic quenching. High quenching constant suggested that LMG can form a complex with BSA. Binding constant and number of binding site were determined. The thermodynamic parameters suggested the main interacting force is hydrophobic forces . The effect of LMG on the conformation of BSA was analyzed by synchronous fluorescence spectroscopy . RLS spectra were also used to reconfirm the formation of complex between BSA and LMG.
研究领域:
生物化学
·
分子生物学
·
光谱学
·
药物代谢
·
蛋白质-配体相互作用
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）