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Jørgen Houmøller Sydney H. Kaufman Dr. Kristian Støchkel Prof. Lokesh C. Tribedi Prof. Steen Brøndsted Nielsen Prof. J. Mathias Weber 《Chemphyschem》2013,14(6):1133-1137
We report electronic spectra of mass‐selected MnO4? and MnO4??H2O using electronic photodissociation spectroscopy. Bare MnO4? fragments by formation of MnO3? and MnO2?, while the hydrated complex predominantly decays by loss of the water molecule. The band in the visible spectral region shows a well‐resolved vibrational progression consistent with the excitation of a Mn? O stretching mode. The presence of a single water molecule does not significantly perturb the spectrum of MnO4?. Comparison with the UV/Vis absorption spectrum of permanganate in aqueous solution shows that complete hydration causes a small blueshift, while theoretical models including a dielectric medium have predicted a redshift. The experimental data can be used as benchmarks for electronic structure theory methods, which usually predict electronic spectra in the absence of a chemical environment. 相似文献
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The effect of magnetic field dependent viscosity on the onset of Bénard-Marangoni ferroconvection in a horizontal layer of ferrofluid is investigated theoretically. The lower boundary is taken to be rigid with fixed temperature, while the upper free boundary at which temperature-dependent surface tension effect is considered is non-deformable and subject to a general thermal condition. The Rayleigh-Ritz method with Chebyshev polynomials of the second kind as trial functions is employed to extract the critical stability parameters numerically. The results show that the onset of ferroconvection is delayed with an increase in the magnetic field dependent viscosity parameter (Λ) and Biot number (Bi) but opposite is the case with an increase in the value of magnetic Rayleigh number (Rm) and nonlinearity of magnetization (M3). Further, increase in Rm, M3, and decrease in Λ and Bi is to decrease the size of the convection cells. 相似文献
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