排序方式: 共有14条查询结果,搜索用时 34 毫秒
1.
L. Margulies N. Friedman M. Sheves Y. Mazur M.E. Lippitsch M. Riegler F.R. Aussenegg 《Tetrahedron》1985,41(1):191-195
Linear dichroism spectra of several retinoids and related polyenes incorporated in stretched polyethylene films were determined. It is suggested that the retinoids are oriented with the plane of the ring parallel to the stretching direction of the film, the long polyene chain being displaced from that direction. 相似文献
2.
Michael C. Zerner Walter M. F. Fabian Renate Dworczak Dietmar W. Kieslinger Gert Kroner Hans Junek Max E. Lippitsch 《International journal of quantum chemistry》2000,79(4):253-266
The effect of conformation (E/Z isomerism), nature (donor/acceptor) of substituents, and endgroups (indandione, pyrazolone, pyrazoledione) on the molecular hyperpolarizability βvec of dicyanomethylene (hetero)aromatic dyes is investigated by means of semiempirical (AM1, ZINDO) molecular orbital calculations. Unless Z isomers are stabilized by intramolecular hydrogen bonding, generally E conformers have larger βvec's. Replacement of one nitrile group of the dicyanomethylene moiety by p‐aminoaryl rather than p‐R‐arylamino (R=NMe2, MeO, H, NO2) is found to be advantageous. Increasing the acceptor strength of 29 by successively replacing the carbonyl with dicyanovinyl groups leads to a maximum of βvec for the derivative with one rather than two C(CN)2 groups. With respect to endgroups, the indandione moiety generally is the least active group. Solvent effects are treated within the framework of the self‐consistent reaction field approximation. In most cases gas‐phase tendencies are either parallel or even reinforced if solvent effects are taken into account. The calculated results are compared with electric field induced second harmonic generation (EFISH) measurements. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 79: 253–266, 2000 相似文献
3.
Franz R. Aussenegg Max E. Lippitsch Humbert M. Noll Erich J. Schieffer 《Physics letters. A》1978,68(2):194-196
The vibrational Raman bands of some simple liquids are investigated on the influence of an external electric dc field. Thereby the electric field strength is varied in the range of 0.1 to 1 MV/cm. The experiments demonstrate that Raman intensities and depolarization ratios increase with increasing field strength and — after passing a maximum — decrease with even higher field strengths. In mixtures the field dependence of Raman intensity takes a different course than in pure liquids. 相似文献
4.
Max E. Lippitsch Johannes Pusterhofer Marco J.P. Leiner Ottow S. Wolfbeis 《Analytica chimica acta》1988
In constrast to existing fluoresensors for oxygen, a sensor is described that measures the decay time of the indicator rather than its emission than its emission intensity. A simple opto-electronic device is described for measuring lifetimes of a long-lived fluorophore with a frequency-modulated LED as light source. Measurement of lifetime provides as more linear Stern-Vomer plot and offers certain advantages with respect to the performance of the sensor, because it has an internal reference system that is an attractive to the frequently-used two-wavelenght referencing method. Long-term stability is distinctly better because the phase shift is independent of indicator bleaching and leaching a well as lamp intensity fluctuations. The detection limit is ca. 2 torr of oxygen. 相似文献
5.
Dietmar Kieslinger Bernhard H. Weigl Sonja Draxler Max E. Lippitsch 《Optical Review》1997,4(1):A85-A88
Glass capillaries with a chemically sensitive coating on the inner surface are used as optical sensors for medical diagnostics.
The capillary simultaneously serves as a sample compartment, a sensor element, and an inhomogeneous optical waveguide. Different
optical setups have been investigated and compared regarding its waveguiding properties. 相似文献
6.
A method developed for quantitative determination of static and dynamic contributions to luminescence quenching is applied to Ru(II) complexes in polymer matrices (silica gel and polystyrene), quenched by oxygen. This method is based on both intensity and lifetime quenching experiments. The curvature of intensity Stern-Volmer plots is related to the results. 相似文献
7.
The nonlinearity of the Raman polarizability of polystyrene is revealed by applying a static electric field of ≈ 1 MV/cm to the sample while measuring the Raman intensity. A special experimental technique allows registration of relative intensity variations of 10-3. The results can be understood using a simple theoretical model. 相似文献
8.
A. Leitner M. E. Lippitsch S. Draxler M. Riegler F. R. Aussenegg 《Applied physics. B, Lasers and optics》1985,36(2):105-109
The fluorescence properties of dye molecules (rhodamine 6G and erythrosin) adsorbed on pure glass surfaces and on silver islands films are investigated by cw and picosecond time-resolved methods. On pure glass surfaces we observe concentration quenching below a critical intermolecular distance (reduction of the fluorescence power per molecule as well as shortened and non-exponential fluorescence decay). On silver islands films the shortening in fluorescence lifetime is more drastic and is nearly independent of the intermolecular distance. This behavior suggests an electrodynamic interaction between dye monomers and plasmons in the metal particles, modified by a damping influence of dye dimers. 相似文献
9.
Donor (anthracene) sensitized acceptor (perylene) fluorescence is quenched more efficiently by halothane than is intrinsic perylene fluorescence. The underlying process of dynamic fluorescence quenching is investigated by time-resolved fluorescence spectroscopy. 相似文献
10.
Gudrun Hermann Max E. Lippitsch Harald Brunner Franz R. Aussenegg Eberhard Müller 《Photochemistry and photobiology》1990,52(1):13-18
Abstract— A comparative study of the picosecond kinetics of rye ( Secale cereale L.) phytochrome, its 39 and 23 kDa chromopeptides and deuterated rye phytochrome has been carried out. Evidence is presented that the fluorescence decay of Pr contains a very short lifetime component (14 ps) which has escaped detection in the fluorescence studies reported so far. Thus, the overall decay is well described by four exponential components, two rapid (14 and 44 ps) and two slower ones (157 and 690 ps). The fluorescence decays of deuterated Pr and of a 39 and 23 kDa chromopeptide of Pr also require the analysis in terms of four exponentials for a good fit. Some of the lifetime and amplitude values obtained differ significantly from the values estimated for Pr. In the chromopeptides, the two longer components have distinctly slower decays. For the two faster components the lifetimes remain approximately the same, but their relative amplitudes vary greatly. In deuterated Pr, the lifetimes are affected only slightly by deuteration. In contrast, the decay amplitudes are strikingly altered. Moreover, from a rate equation simulation modelling the observed fluorescence kinetics, it turns out that the yields for the various deactivation steps in the chromopeptides and in deuterated Pr reveal differences from the corresponding values in Pr. The implications of the results presented with respect to the influence of the protein moiety of Pr on the picosecond relaxation process are discussed. 相似文献