查看更多>>摘要：Due to the reversible trans-cis geometric isomerization reaction between trans- and cis-2-methyl-cyclopropanecarboxylic acid (MCA) in gas-phase, it is impossible to distinguish them by linear infrared spectroscopy experiments. We show that the spectral signatures between trans- and cis-MCA are well resolved in ab initio calculated gas-phase electron-vibration-vibration two-dimensional infrared (EVV 2DIR) spectra. We further analyse the vibration mode pairs that mainly contribute to the intensity of these characteristic cross-peaks. Our work suggests that the EVV 2DIR technique can be used to in situ detect the concentration ratio of each species in the reversible reaction processes.
查看更多>>摘要：To explore the mechanism of intermolecular hydrogen bond relating to PRODAN derivative 2b in methanol solvent on photoexcitation process, spectral behavior calculations of PRODAN-2b and its hydrogen bonding complex were studied by using density functional theory (DFT) and time-dependent density functional theory (TDDFT). After photo excitation, the hydrogen bond between PRODAN-2b and methanol become stronger. It was found that with the increase in the number of methanol molecules, the more hydrogen bonds between PRODAN2b and methanol were formed and the hydrogen bondings were also enhanced. Further evidence for enhanced hydrogen bond due to intramolecular charge transfer excitation character of PRODAN-2b is presented. This effect leads to the red shift of absorption and fluorescence spectra of PRODAN-2b molecules in methanol solvent with increasing methanol concentration.
查看更多>>摘要：Mg2Sn films with nano-sized metal Sn phase were prepared by magnetron sputtering. The nano-sized metal Sn phase in films gradually increased with increasing single sputtering time on alloy target. The carrier concentration increased and the carrier mobility first decreased and then slightly increased with increasing nano-sized metal Sn phase. The resistivity and Seebeck coefficient all exhibited a trend of first increasing and then decreasing with the increase of nano-sized metal Sn phase. The Seebeck coefficient greatly increases due to existing moderate nano-sized secondary phase. It is beneficial to increase the power factor that the cubic Mg2Sn thin films contain an appropriate amount of conductive nano-sized metal Sn phase.
查看更多>>摘要：In this article the equilibrium saturated solubility of glycine, DL-alanine and L-threonine in aqueous ammonium sulphate media at various temperatures were estimated. The standard transfer Gibbs free energies and different thermodynamic parameters were also estimated. Different interactions were analysed for the solvation of the amino acids in the experimental media to explain the mechanism of solvation. For DL-alanine and L-threonine, salting-in effect is observed at lower electrolyte concentration while at higher electrolyte concentration salting out effect is observed at a particular temperature. The chemical stability of the amino acids in aqueous electrolyte mixture was explained to justify the experimental results.
Birczynski, ArturSzymocha, Agnieszka M.glarz, Wladyslaw P. WeLalowicz, Zdzislaw T....
5页
查看更多>>摘要：There are two typical ranges of temperature observed in mobility of molecules in confinement of eg. zeolite structure: translational mobility above T-S, and localized molecules below T-S. NMR spectra and relaxation for acetone-d(6) in D-ZSM-5 were obtained in a wide temperature range. NMR results were analyzed and compared with previous results for acetone-d6 in NaX and NaY zeolites. A lot of attention was dedicated to internal rotation of methyl groups, both above and below T-S. An evidence was given for existence of acetone dimers in confinement of D-ZSM-5 in the temperature range 267 K-151.5 K.
NSTL
Elsevier