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951.
Elisa Biasin Tim B. van Driel Gianluca Levi Mads G. Laursen Asmus O. Dohn Asbjørn Moltke Peter Vester Frederik B. K. Hansen Kasper S. Kjaer Tobias Harlang Robert Hartsock Morten Christensen Kelly J. Gaffney Niels E. Henriksen Klaus B. Møller Kristoffer Haldrup Martin M. Nielsen 《Journal of synchrotron radiation》2018,25(2):306-315
Time‐resolved X‐ray scattering patterns from photoexcited molecules in solution are in many cases anisotropic at the ultrafast time scales accessible at X‐ray free‐electron lasers (XFELs). This anisotropy arises from the interaction of a linearly polarized UV–Vis pump laser pulse with the sample, which induces anisotropic structural changes that can be captured by femtosecond X‐ray pulses. In this work, a method for quantitative analysis of the anisotropic scattering signal arising from an ensemble of molecules is described, and it is demonstrated how its use can enhance the structural sensitivity of the time‐resolved X‐ray scattering experiment. This method is applied on time‐resolved X‐ray scattering patterns measured upon photoexcitation of a solvated di‐platinum complex at an XFEL, and the key parameters involved are explored. It is shown that a combined analysis of the anisotropic and isotropic difference scattering signals in this experiment allows a more precise determination of the main photoinduced structural change in the solute, i.e. the change in Pt—Pt bond length, and yields more information on the excitation channels than the analysis of the isotropic scattering only. Finally, it is discussed how the anisotropic transient response of the solvent can enable the determination of key experimental parameters such as the instrument response function. 相似文献
952.
Iben Skovsen Mogens Christensen Henrik Fanoe Clausen Jacob Overgaard Christian Stiewe Titas Desgupta Eckhard Mueller Mark A. Spackman Bo B. Iversen 《ChemInform》2010,41(51):no-no
Hexagonal CeMnNi4 is synthesized by high‐frequency induction melting of stoichiometric amounts of the elements with subsequent Czochralski crystal pulling. 相似文献
953.
954.
955.
Josephine S. Lübeck Jan H. Christensen Giorgio Tomasi 《Journal of separation science》2023,46(1):2200668
A nontarget screening method was developed based on D-optimal designs for ultra-high performance supercritical fluid chromatography with positive and negative electrospray ionization mode mass spectrometry. A mixture of organic contaminants such as pesticides, steroids, surfactants, phenolic and fatty acids, and polycyclic aromatic hydrocarbon derivatives, was used for the optimization. An aprotic mixture of dichloromethane and acetone [3:1] performed overall best as the injection solvent. The highest peak capacities (n) were accomplished at the shallowest gradient (1%B/min), ammonium formate (n = 378 in negative ionization mode), or ammonium acetate (n = 327 in positive ionization mode) in methanol as the modifier. Capillary voltage, make-up solvent flow rate, water, and additive concentration were the most significant factors for improving peak intensity: higher peak intensities were obtained at lower additive concentrations (5mM ammonium formate), and with 5% water in positive ionization mode. Conversely, water had detrimental effects in negative ionization mode. The optimized method was used to quantify organic contaminants in 17 freshwater sediment samples from Copenhagen, Denmark. Out of 50 monitored contaminants, 35 were detected in at least one sample. Further, the method has a potential for target and nontarget screening analysis of organic contaminants in solid matrices. 相似文献