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991.
A short derivation of the local harmonic approach and ATDHF is given which elucidates the formal similirity between them. The conditions for the validity of the approaches are studied. We show first, that they are related to deviation forces within second order RPA which drive the system out of the collective mode, and second, that the local harmonic approach is more restricted than ATDHF. 相似文献
992.
The dynamic behavior of transient EPR nutation signals during the first 100 ns after N2-laser excitation or molecular triplet states in single crystals has been investigated. The onset of the signal is found to depend on the inhomogeneous width and form of the cw EPR line With phenazine (in fluorene) a time resolution of 15 ns could be demonstrated. 相似文献
993.
In this paper we study boundary eigenvalue problems for first order systems of ordinary differential equations of the form \[zy'\left( z \right) = \left( {\lambda A_1 \left( z \right) + A_0 \left( z \right)} \right)y\left( z \right),\,\,y\left( {ze^{2\pi i} } \right) = e^{2\pi iv} y\left( z \right)\] for z ? Slog, where S is a ring region around zero, Slog denotes the Riemann surface of the logarithm over S, the coefficient matrix functions A1(z) and A0(z) are holomorphic on S, and v is a complex number. The eigenfunctions of this eigenvalue problem are the Floquet solutions of the differential system with v as characteristic exponent. For an open subset S0 of S, the notion of A1-convexity of the pair (S0, S) is introduced. For A1-convex pairs (S0, S) it is shown that the expansion into eigenfunctions and associated functions of holomorphic functions on Slog, satisfying the monodromy condition y(ze2πi) = e2πivy(z), converges regularly on Slog0 and is unique. If S is a pointed neighbourhood of 0 and A1(z) is holomorphic in SU{0}, it is shown that there is a pointed neighbourhood S0 of 0 such that (S0, S) is A1-convex. It follows from the results of this paper that many expansions of analytic functions in terms of special functions can be considered as eigenfunction expansions of this kind. 相似文献
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Reinhard Niessner Wilfried Robers Andreas Krupp 《Fresenius' Journal of Analytical Chemistry》1991,341(3-4):207-213
Summary Laser-induced fluorescence is introduced as an analytical technique for the detection of particle-bound PAHs, which can be found as a result of most combustion processes. A quartz fiber is used to couple the light of a frequency-doubled excimer-pumped dye laser into the sensor head. The fluorescence light is detected using collecting optics, a set of interference filters and a photomultiplier. PAHs in different forms (crystalline, as homogeneous particles and coated on NaCl particles) were investigated. Fluorescence spectra and time-resolved signals, which exhibit characteristic decay times, are presented. 相似文献