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1.
T. Engel M. Würtz S. Borneis St. Becker I. Klaft A. Kohl T. Kühl F. Laeri D. Marx K. Meier R. Neumann F. Schmitt P. Seelig L. Völker 《Hyperfine Interactions》1997,108(1-3):251-258
Laser spectroscopy at storage rings often suffers from a limited resolution due to Doppler-broadened resonances. Broadening
is caused by the velocity spread of the ions stored in the beam. In the following, the present status of our work on laser
systems specialized on the specific needs of laser spectroscopy at storage rings is reported.
Two pulsed laser systems were developed. One is a dye laser whose spectral bandwidth can be switched by inserting different
Littrow-prisms into the resonator. An increase in bandwidth up to a factor of 45 was achieved. This laser was used for fast
qualitative scans and high resolution measurements. The other laser system is a Nd : YAG laser pumped optical parametric oscillator.
It is a tunable laser system covering the spectral range from 410 to 4000 nm. Furthermore, a continuous wave laser with a
frequency shifted feedback cavity is described. It shows broadband emission with an adjustable bandwidth of up to 4.5 GHz.
This laser can be advantageous for laser cooling of ion beams.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
Of concern are systems of linear evolution equations
相似文献
3.
4.
Christophe Curty Norbert Engel Jos Iturraspe Albert Gossauer 《Photochemistry and photobiology》1995,61(6):552-556
Photooxygenation of (pyropheophorbidato a methyl ester)cadmium (II) was studied using 18,18O2 labeling of the molecular oxygen required for cleavage of the macrocycle. After reductive demetallation of the primary oxidation product (4,5-dioxo-4,5-secopyropheophorbidato a methyl ester)cadmium (II), the isotope content of formylbilinone 4a was analyzed by repeated-scan fast atom bombardment mass spectrometry. Comparison of the spectroscopic data of the labeled pigment 4a with the statistical probabilities of18 O isotope incorporation calculated for four possible reaction mechanisms clearly proves that photooxidative ring cleavage occurred by the one-molecule mechanism, i.e. the terminal oxygen atoms of 4a were derived from one oxygen molecule. Furthermore, a study of the exchange of the18 O-labeled atoms revealed that no exchange occurs within the pH 4.5–9.5 range. In stronger alkaline or acidic solutions, only the oxygen atom of the formyl group is exchanged. Hydrolysis of the methyl ester group of 4a was achieved, without loss of the18 O label on the formyl group, at pH 7.2 in the presence of pig liver esterase. 相似文献
5.
Yang J Bos R Belder GF Engel J Busscher HJ 《Journal of colloid and interface science》1999,220(2):410-418
The aim of this paper is to determine to what extent (i) deposition of oral bacteria and polystyrene particles, (ii) onto quartz and dental enamel with and without a salivary conditioning film, (iii) in a parallel plate (PP) and stagnation point (SP) flow chamber and at common Peclet numbers are comparable. All three bacterial strains showed different adhesion behaviors, and even Streptococcus mitis BMS, possessing a similar cell surface hydrophobicity as polystyrene particles, did not mimic polystyrene particles in its adhesion behavior, possibly as a result of the more negative ζ potentials of the polystyrene particles. The stationary endpoint adhesion of all strains, including polystyrene particles, was lower in the presence of a salivary conditioning film, while also desorption probabilities under flow were higher in the presence of a conditioning film than in its absence. Deposition onto quartz and enamel surfaces was different, but without a consistent trend valid for all strains and polystyrene particles. It is concluded that differences in experimental results exist, and the process of bacterial deposition to enamel surfaces cannot be modeled by using polystyrene particles and quartz collector surfaces. 相似文献
6.
Cooperative conformational transitions of proteins and nucleic acids are of decisive importance to many processes of molecular biology, and particularly to their regulation. They proceed via numerous interdependent elementary processes, and their kinetics are therefore often complicated. They are frequently also very fast. However, kinetic analyses can be carried out by chemical relaxation methods. The theoretical interpretation is comparatively simple in the case of linear biopolymers. When the linear Ising model extended for kinetics was applied to model peptides and polynucleotides, it provided an insight into the fundamental principles of cooperative transformations. 相似文献
7.
Motivated by pump-probe experiments of I(2) in a room-temperature sample, the detection of fractional revivals is investigated using full-dimensional quantum wave packet calculations. It is shown that the structures observed in the pump-probe signal depend sensitively on the probe parameters employed and that the observed signal reflects a particular phase effect between fractional revivals. 相似文献
8.
V. Kolarik M. Juez-Lorenzo W. Engel N. Eisenreich 《Fresenius' Journal of Analytical Chemistry》1993,346(1-3):252-254
Summary The formation of -Fe2O3 on Fe3O4 during the oxidation of iron below 570°C occurs very slowly and the scales are so thin that they cannot be detected by microscopy. X-ray diffraction with grazing incidence, equipped with a high temperature device, allows an in situ study of the -Fe2O3 formation even the initial reactions. The formation of -Fe2O3 was studied in isothermal experiments at 400, 450, 500 and 550°C. -Fe2O3 could already be detected at the beginning of the experiments. The difference method, a numerical treatment for kinetic evaluation, yields curves showing the growth of the -Fe2O3 layer. Fitting the parabolic time law to these curves yields the rate constants. 相似文献
9.
Klaus-J. Engel 《Monatshefte für Mathematik》1995,119(4):259-265
In this note we prove some results on the m-accretivity of sums and products of linear operators. In particular we obtain the following theorem: LetA, B be two m-accretive operators on a reflexive Banach space. IfA is invertible and (A)–1
B is accretive thenBA
–1 andA+B are m-accretive. 相似文献
10.
F. Reinert P. Steiner Th. Engel S. Hüfner 《Zeitschrift für Physik B Condensed Matter》1995,99(2):223-227
Electron-energy loss spectra of potassium permanganate (KMnO4) with primary electron energies 25 eV<=E0<=500 eV show 7 peaks in the energy-loss range 1 eV<=ΔE<=10eV and are successfully analysed with a superposition of 7 independent Gaussians. The intensity of these lines follow roughly a power-law dependence on the primary energy I∝E 0 -α . There are two groups of lines, the first with an exponent α≈0.5, while the lines in the second group decay much stronger with increasingE 0 corresponding to a value 0.9<=α<=1.3. The 4 lines in the first group are identified as dipole allowed transitions by comparison to recent first principle molecular-orbital calculations for the (MnO4) molecule by H. Nakai et al. The dipole-allowed excitation spectrum obtained from this analysis agrees very well with these first principle calculations. 相似文献
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