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151.
Ryezayeva N Hartmann T Kalmykov Y Lenske H von Neumann-Cosel P Ponomarev VY Richter A Shevchenko A Volz S Wambach J 《Physical review letters》2002,89(27):272502
A high-resolution (gamma,gamma') study of the electric dipole response in 208Pb at the S-DALINAC reveals a resonance structure centered around the neutron emission threshold. Microscopic quasiparticle phonon model calculations in realistic model spaces including the coupling to complex configurations are able to describe the data in great detail. The resonance is shown to result from surface density oscillations of the neutron skin relative to an approximately isospin-saturated core. It also forms an integral part of a toroidal E1 mode representing an example of vortex collective motion in nuclei. 相似文献
152.
Development of a tunable mid-IR difference frequency laser source for highly sensitive airborne trace gas detection 总被引:4,自引:0,他引:4
Richter D Fried A Wert BP Walega JG Tittel FK 《Applied physics. B, Lasers and optics》2002,75(2-3):281-288
The development of a compact tunable mid-IR laser system at 3.5 μm for quantitative airborne spectroscopic trace gas absorption
measurements is reported. The mid-IR laser system is based on difference frequency generation (DFG) in periodically poled
LiNbO3 and utilizes optical fiber amplified near-IR diode and fiber lasers as pump sources operating at 1083 nm and 1562 nm, respectively.
This paper describes the optical sensor architecture, performance characteristics of individual pump lasers and DFG, as well
as its application to wavelength modulation spectroscopy employing an astigmatic Herriott multi-pass gas absorption cell.
This compact system permits detection of formaldehyde with a minimal detectable concentration (1σ replicate precision) of
74 parts-per-trillion by volume (pptv) for 1 min of averaging time and was achieved using calibrated gas standards, zero air
background and rapid dual-beam subtraction. This corresponds to a pathlength-normalized replicate fractional absorption sensitivity
of 2.5×10-10 cm-1.
Received: 29 April 2002 / Published online: 21 August 2002
RID="*"
ID="*"Corresponding author. Fax: +1-303/497-1492, E-mail: dr@ucar.edu 相似文献
153.
A geometric approach to asymptotic expansions for large-deviation probabilities, developed for the Gaussian law by Breitung and Richter [J. Multivariate Anal.,58, 1–20 (1996)], will be extended in the present paper to the class of spherical measures by utilizing their common geometric properties. This approach consists of rewriting the probabilities under consideration as large parameter values of the Laplace transform of a suitably defined function, expanding this function in a power series, and then applying Watson’s lemma. A geometric representation of the Laplace transform allows one to combine the global and local properties of both the underlying measure and the large-deviation domain. A special new type of difficulty is to be dealt with because the so-called dominating points of the large-deviation domain degenerate asymptotically. As is shown in Richter and Schumacher (in print), the typical statistical applications of large-deviation theory lead to such situations. In the present paper, consideration is restricted to a certain two-dimensional domain of large-deviations having asymptotically degenerating dominating points. The key assumption is a parametrized expansion for the inverse $\bar g^{ - 1} $ of the negative logarithm of the density-generating function of the two-dimensional spherical law under consideration. 相似文献
154.
For an integer n ? 1, a graph G has an n-constant crossing number if, for any two good drawings ? and ?′ of G in the plane, μ(?) ≡ μ(?′) (mod n), where μ(?) is the number of crossings in ?. We prove that, except for trivial cases, a graph G has n-constant crossing number if and only if n = 2 and G is either Kp or Kq,r, where p, q, and r are odd. 相似文献
155.
J. Rothe J. Pollmann R. Franke J. Hormes H. Bönnemann W. Brijoux K. Siepen J. Richter 《Fresenius' Journal of Analytical Chemistry》1996,355(3-4):372-374
Transition metal colloids are potential precursors of heterogeneous catalysts with application to selective chemical reactions. Sample preparation techniques are described. Experimental details are given of the characterization of these often air-sensitive particles by X-ray photoelectron and X-ray absorption spectroscopy. First results obtained with both techniques for a Rh-colloid show that the metal is mainly present in the zerovalent chemical state. But the spectra indicate further chemical states of Rh which can be assigned to the outermost metal atoms of the colloid interacting with organic ligands or to the educt Rh-halides. 相似文献
156.
G. Kühler D. Meuer S. Müller A. Richter E. Spamer O. Titze W. Knüpfer 《Physics letters. [Part B]》1981,104(3):189-193
Low momentum transfer, high-resolution inelastic electron scattering on 208Pb has been used to study the distribution of E1 and E2 strength in the region of excitation energy Ex = 8?12MeV. The E1 and E2 strength is very fragmented and the EWSR strength amounts to (10+7?6)% and (29+11?8)% in the investigated energy region, respectively. The E2 strength found is less than most current theoretical predictions but agrees qualitatively with a 1p - 1h +2p - 2h model calculation presented in this paper. The E2 strength is also smaller than what is known from hadron scattering and the shape of the strength distribution is also markedly different in electron and hadron scattering. 相似文献
157.
D. Bender G. Eulenberg A. Richter E. Spamer B.C. Metsch W. Knüpfer 《Nuclear Physics A》1983,398(3):408-414
Following the studies of the distribution of M1 strength in the even-even N = 28 isotones 48Ca, 50Ti, 52Cr and 54Fe by inelastic electron scattering, the result of a search for M1 transitions in the odd-even N = 28 nucleus 51V is reported. No strong M1 excitation has been detected, in contrast to a recent (p, p') experiment. There is no immediate explanation for this discrepancy. Shell-model calculations indicate that a part of it might be accounted for by an interference between the spin and orbital term of the electromagnetic transition operator in the (e, e') experiment. 相似文献
158.
P. Wastyn H. Genz M. Mutterer A. Richter G. Schrieder J.C. Van Staden J.P. Theobald 《Nuclear Physics A》1979,320(2):433-448
Cross sections for elastic scattering of 40Ar on 40Ca have been measured at energies Elab = 191, 236 and 272 MeV employing position-sensitive detectors and the method of kinematical coincidences. The experimental data are first compared with the ordinary and the generalized Fresnel models. Only the generalized Fresnel model describes the experimental data well. An optical model analysis with a Woods-Saxon potential yields an energy independent set of parameters (VR = ?21.76 MeV, rOR = 1.37 fm, aR = 0.45 fm; W1 = ?13.69 MeV, r01 = 1.40 fm, a1 = 0.36 fm) very similar to the one found in 40Ca-40Ca scattering at corresponding energies. Values deduced for the total reaction cross sections for the three energies are in good agreement with those predicted by the generalized Fresnel model. The data are also compared with optical model calculations with the real part of the potential replaced by various microscopically determined potentials. The proximity, Fleckner-Mosel and the Krappe-Nix-Sierk potentials like the phenomenological optical model potential reproduce the measured data fairly well over several orders of magnitude. 相似文献
159.
Linda Jean Richter 《Israel Journal of Mathematics》1979,32(1):27-31
IfF is an automorphism of the degrees of unsolvability that preserves the jump operator, thenF leaves fixed all the degreesc that satisfyc≧0
(3).
The results of this paper were part of the author’s PhD thesis (Illinois 1977), supervised by Carl G. Jockusch, Jr. 相似文献
160.
H. Bretschneider W. Richter W. Klötzer 《Monatshefte für Chemie / Chemical Monthly》1965,96(6):1661-1676
Zusammenfassung Es wird über 4 verschiedene Synthesen des 4-Sulfanilamido-5,6-dimethoxypyrimidins2 berichtet.Frau Prof. Dr. Dr.E. Cremer zum Geburtstage in Verehrung gewidmet.14. Mitt.:H. Bretschneider, J. Dehler undW. Klötzer, Mh. Chem.95, 207 (1964). 相似文献