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91.
92.
Chemiionization of alkali atoms by active nitrogen is studied in a crossed beam apparatus. Vibrationally excited N2 in the electronic ground state is responsible for the ionization rather than electronically excited N2 in the A 3∑u+ state. The ionization cross section is of the order 102 A2. The experimental data is consistent with the distribution of the vibrational levels of N2 (X1 ∑g+) predicted by Bray or Caledonia and Center. 相似文献
93.
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95.
Molecular dynamic simulations are carried out in order to investigate the stability of the secondary and tertiary structure of the intermediate filaments monomer unit of wool. Based on the assumed secondary structure three segments of the primary structure are selected: 1A, L1,2 and a part of 2B. With the ideal α-helix as start conformation, the simulations are carried out with the MD-algorithm of DISCOVER 2.9.0 (BIOSYM, 1993) and the CFF91 force field for 500 ps at different temperatures in vacuum. In either simulation a destabilization of the helical structure with an increase of the simulation temperature is observed. By monitoring the length distribution of the axially oriented (O···H)-hydrogen bonds, which stabilize the helical structure, transition temperatures for the α-helical denaturation are determined. The supposedly α-helical segments 1A and 2B show significantly higher transition temperatures than segment L1,2. This lower temperature confirms the expectation from the amino acid sequence that the linker segment shows more conformational flexibility and is nonhelical at room temperature. 相似文献
96.
R.H. Blick D.W. van der Weide R.J. Haug K. von Klitzing K. Eberl 《Superlattices and Microstructures》1998,23(6):1265-1271
We investigate the photoconductance through a double quantum dot or ‘artificial molecule’ induced by a broadband millimeter wave source. This source functions as a heterodyne interferometer, consisting of two nonlinear transmission lines generating harmonic output in the range of 2–400 GHz, and, being coherent, allows tracking of the induced current of the sample in both magnitude and phase. This enables us to monitor effects related to coherent electronic transport through these ‘artificial molecules’. 相似文献
97.
Wool is a fibrous biomaterial with an exceptional multicellular structure and complex chemical composition. This is shown for some selected topics. 相似文献
98.
Mathematical models are developed to calculate the temperatures, pressures and stresses during laser shock processing for time-modulated (ramp-up, ramp-down and rectangular) laser pulses. Three different shock processing configurations are also considered: non-ablative exposure, ablative exposure and confined ablation with coating. The results for iron show that the plasma pressure reaches an average value of 9 GPa in direct ablation configuration and plays a dominant role for all three types of laser pulses. In the case of confined geometry, the plasma pressure reaches an average value of 20 GPa. All calculated pressures and stresses exceed the yield strength of the workpiece, indicating plastic deformation. It is also shown that pulses with short rise times yield higher plasma pressures. 相似文献
99.
S. Schmitt-Rink C. Ell S.W. Koch H.E. Schmidt H. Haug 《Solid State Communications》1984,52(2):123-125
A microscopic theory of many-body effects in the lowest subbands of semiconductor multiple quantum well structures is presented. The renormalized subband levels are calculated for a broad temperature range and optical bistability due to induced absorption is predicted. 相似文献
100.
Alkyl chain effects in thin films of substituted phthalocyanines studied using infrared spectroscopy
Thin films (2-50 nm) of unsubstituted and 1,4-octa-alkyl substituted zinc phthalocyanines were investigated using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, whereas the alkyl chains are C4H7, C7H13, C10H19. The absorption bands in the whole spectral range are discussed. We observe distinct differences in the spectra between the alkyl substituted Phthalocyanine (Pc) compounds. In contrast to PcZn and (but)8PcZn, the spectra of (hep)8PcZn and (dec)8PcZn show two additional features in the spectral range between 3700 and 3000 cm−1, which are discussed in detail. 相似文献