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91.
Toffoli D Lucchese RR Lebech M Houver JC Dowek D 《The Journal of chemical physics》2007,126(5):054307
The authors report measured and computed molecular frame photoelectron angular distributions (MFPADs) and recoil frame photoelectron angular distributions (RFPADs) for the single photon ionization of the nonlinear molecule NO2 leading to the (1a2)-1 b 3A2 and (4a1)-1 3A1 states of NO2+. Experimentally, the RFPADs were obtained using the vector correlation approach applied to the dissociative photoionization (DPI) involving these molecular ionic states. The polar and azimuthal angle dependences of the photoelectron angular distributions are measured relative to the reference frame provided by the ion recoil axis and direction of polarization of the linearly polarized light. Experimental results are reported for the photon excitation energies hnu=14.4 and 22.0 eV. Theoretically the authors give expressions for both the MFPAD and the RFPAD. They show that the functional form in the recoil frame, where an average over the azimuthal dependence of the molecular fragments about the recoil direction is made, is identical to that they have earlier found for the DPI experiments performed on linear molecules. MFPADs were then computed using single-center expansion techniques within the fixed-nuclei frozen-core Hartree-Fock approximation. The computed cross sections for ionization to the (1a2)-1 b 3A2 state show a strong propensity for ionization with the polarization of the light perpendicular to the plane of the molecule, whereas the ionization to the (4a1)-1 3A1 state of the ion is of similar intensity for all orientations of the polarization of the light in the molecular frame. These qualitative features of the MFPAD are also evident in the RFPAD. The RFPAD for ionization leading to the (1a2)-1 b 3A2 state is strongly peaked in the perpendicular orientation, whereas the RFPAD for ionization leading to the (4a2)-1 3A1 state is much more nearly isotropic. Comparison between experimental and theoretical RFPADs indicates that the recoil angle for NO+ fragments is approximately 50 degrees relative to the symmetry axis of the initial C2v symmetry of the NO2 molecule in the ionization leading to the (1a2)-1 b 3A2 state and the recoil angle is approximately 120 degrees for the O+ fragment for ionization leading to the (4a1)-1 3A1 state. 相似文献
92.
Dr. María Rodríguez‐Castillo Gustavo Lugo‐Preciado Dr. Danielle Laurencin Dr. Frederik Tielens Dr. Arie van der Lee Dr. Sébastien Clément Dr. Yannick Guari Dr. José M. López‐de‐Luzuriaga Dr. Miguel Monge Dr. Françoise Remacle Dr. Sébastien Richeter 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(30):10680-10680
93.
Bassanese DN Crawford-Clark S Bowen BJ Henderson LC Barnett NW Conlan XA 《Journal of separation science》2012,35(9):1110-1117
The need to monitor biogenic amines levels is essential for many areas of the food industry for two main reasons: the caustic nature and potential toxicity of these amines, and the potential to use amine levels as markers for freshness and quality in foodstuffs. Optimised analysis conditions used for the determination of biogenic amines derivatised with 2-napthyloxycarbonyl chloride has been applied to different pet food samples to assess the effectiveness of this method for complex sample matrices. Further to this, the use of high-resolution mass spectrometry has enabled the previously unconfirmed derivatised form of seven biogenic amines to be established. The derivatised forms identified include as mono substituted (tryptamine and histamine), bisubstituted (putrescine, cadaverine and tyramine), trisubstituted (spermidine) and tetrasubstituted (spermine). The methodology of biogenic amine determination was performed successfully to a range of pet food products highlighting the applicability to a variety of complex sample matrices. 相似文献
94.
Claude Vallée Camelia Lerintiu Jamal Chaoufi Danielle Fortuné Michael Ban Kossi Atchonouglo 《Journal of Elasticity》2013,112(2):111-138
Generalized Standard Materials are governed by maximal cyclically monotone operators and modeled by convex potentials. Géry de Saxcé’s Implicit Standard Materials are modeled by biconvex bipotentials. We analyze the intermediate class of n-monotone materials governed by maximal n-monotone operators and modeled by Fitzpatrick’s functions. Revisiting the model of elastic materials initiated by Robert Hooke, and insisting on the linearity, coaxiality and monotonicity properties of the constitutive law, we illustrate that Fitzpatrick’s representation of n-monotone operators coming from convex analysis provides a constructive method to discover the best bipotential modeling a n-monotone material. Giving up the symmetry of the linear constitutive laws, we find out that n-monotonicity is a relevant criterion for the materials characterization and classification. 相似文献
95.
Danielle L. Gray 《Journal of solid state chemistry》2007,180(5):1527-1532
The interlanthanide compounds Er3SmS6, Er3SmSe6, and Er1.12Sm0.88Se3 have been synthesized from stoichiometric reactions of the elements in a KI salt flux at 1273, 1173, and 1123 K, respectively. Er3SmS6 and Er3SmSe6, which are isostructural and ordered, crystallize in space group P21/m in the ScEr3S6 structure type whereas Er1.12Sm0.88Se3, in which the Er and Sm atoms are disordered, crystallizes in space group Pnma in the U2S3 structure type. Er3SmS6 is a paramagnet with a μeff=11.25(1) μB/mol. From optical measurements a direct band gap of 2.0 eV for light perpendicular to the (100) crystal face of Er3SmSe6 is derived whereas for isostructural Er3SmS6 an optical transition at 2.2-2.4 eV and a broad absorption peak at lower energies are observed. 相似文献
96.
The effect of immobilization in an albumin-glutaraldehyde crosslinked matrix on the structure and activity of a photosystem
I submembrane fraction has been studied. The photosynthetic activity recovered after immobilization was between 35 and 45%
of the oxygen-uptake rates of the native material. Resulting oxygen uptake activities found in immobilized photosystem I preparations
with methylviologen as acceptor were as high as 270 μmol O2 (mg Chl h)-1, An enhancement of photosystem I electron transfer, which is produced by incubation of thylakoid membranes at temperatures
above 30 °C, was detected in native submembrane fractions, but not in the immobilized preparations. It is suggested that the
increased activity at high temperature results from conformational modifications not allowed in the immobilization matrix.
The insensitivity of immobilized photosystem I particles to prolonged storage at 4°C and to strong light exposure, as well
as their high electron-transfer rates, demonstrates that the immobilization procedure used can be successfully applied to
submembrane fractions. 相似文献
97.
Franke D Egger CC Smarsly B Faul CF Tiddy GJ 《Langmuir : the ACS journal of surfaces and colloids》2005,21(7):2704-2712
A double-tailed polymerizable (pyrrolylalkyl) ammonium amphiphile has been synthesized, and its interfacial properties and aqueous phase behavior have been studied by polarized optical microscopy and X-ray diffraction. The Krafft temperature is about 27 degrees C, and the critical micelle concentration at 40 degrees C is about 1 mM, as obtained from surface tension measurements, potentiometry, and isothermal titration calorimetry. The lyotropic behavior of the surfactant is found to be of a complex nature. At concentrations higher than the micellar (L1) region, two mesophases have been identified: a second isotropic (L2) phase, which is probably micellar but not fully miscible with water, and a lamellar (L(alpha)) phase, showing interesting alignment properties. Small-angle X-ray scattering analysis of the mesophases has been evaluated in terms of a model of spherical micelles, which describes a mutual arrangement by a structure factor derived from a hard-sphere potential (Percus-Yevick, "PY", approach). Interest in the comprehensive phase behavior of the polymerizable surfactant is based on the desire to integrate the system into a composite material to obtain potentially conducting self-assembled hybrid mesostructures. 相似文献
98.
A new family of potent aminoacid-type organogelators obtained via an easy and unexpensive way is described. We demonstrated that structural variations onto the side chains of the aminoacid derivatives allowed modulations of the gelation properties. The organogelators bearing a benzyl or an isopropyl group (compounds 1e, 2a, and 2c) are able to provide gelation of apolar solvents at very low concentration (0.2 wt %) and to form thermostable gels. 相似文献
99.
Danielle Dowek Galip Tepehan Helmut Madeheim Rainer Hippler 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1992,22(4):735-740
A polarization study of Lyman-α radiation emitted in collisions of H+, H, He+, and He projectiles with H2 molecules has been performed at projectile energies ranging from 1–25 keV. In H+?H2 and H?H2 collisions, the measured linear polarization is negative at low incident velocities, indicating a preferred alignment of the excited electron charge cloud perpendicular to the incident projectile direction. This is taken as significance for a rotational coupling which in these two collision systems predominantly populates the H(2p ±1) substates. In He+?H2 and He?H2 collisions, the measured linear polarization is about zero and independent of the projectile energy. In these more asymmetric systems,a′?a′ and a′?a″ couplings are now of comparable magnitude. 相似文献
100.
The synthesis of 3,6-bis(3,4-dimethoxybenzoyl)-1,2,4,5-tetrazine (2) and the scope of its reactivity in inverse electron demand Diels-Alder reactions are disclosed representing the first systematic study of the [4 + 2] cycloaddition reactions of 3,6-diacyl-1,2,4,5-tetrazines. 相似文献