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991.
Ch. Lisdat N. Vanhaecke D. Comparat P. Pillet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(3):299-309
Two-photon photoassociation spectra in a Λ-type excitation scheme are analysed under the systematically varied experimental conditions of frequency detunings and laser
intensities. Line shape fits are presented as well as the investigation of intensity and detuning dependent line shifts. From
both we determine the attained spectroscopic precision, that is corrected for a systematic line shift due to the thermal distribution
of atoms in the trap. An energy correction for this effect is given. Information about the feasibility of generating translationally
cold molecules in a well defined rotational and vibrational level by the photoassociation process is derived from the analysis.
Received 21 May 2002 Published online 15 October 2002
RID="a"
ID="a"Current address e-mail: christian.lisdat@ptb.de
RID="b"
ID="b"e-mail: pierre.pillet@lac.u-psud.fr 相似文献
992.
L. N. Bochkarev T. A. Zheleznova A. V. Safronova M. S. Drozdov S. F. Zhil'tsov L. N. Zakharov G. K. Fukin S. Ya. Khorshev 《Russian Chemical Bulletin》1998,47(1):165-168
Triphenyl[tris(tetrahydrofuran)]ytterbium, Ph3Yb(THF)3 (1), was synthesized in high yields by the reaction of Yb with an excess of Ph2Hg or Ph3Bi in the presence of catalytic amounts of YbI2(THF)4 as well as by the reaction of Ph2Yb(THF)2 (2) with Ph2Hg or Ph3Bi. The crystal structure of complex1 was studied by X-ray structural analysis.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 163–166, January, 1998. 相似文献
993.
994.
995.
V. V. Boldyrev 《Journal of Thermal Analysis and Calorimetry》1993,40(3):1041-1062
A review of studies of reactivities of solids is presented, concentrating on localization and autolocalization phenomena.
Some examples of feed-back and structure of the reaction zone are given.
Plenary lecture 相似文献
996.
Reaction of a Cyclic Bis(amino)germylene with Germaniumazides: Trapping-Reactions of Unstable Germa-Imines . The cyclic bis(amino)germylene 1 reacts with different germaniumazides of the type Me2Si(NtBu)2Ge(R)N3 (R = Me ( 2 ), tBu ( 3 ), N(SiMe3)2 ( 4 ), R = N3 ( 5 )). With the exception of 4 all azides lose dinitrogen when treated with 1 and the GeII center coordinates the α-nitrogen of the azide group. It seems to be reasonable to assume a transient germaimine (nitride) which is trapped by further reaction with the azide molecules 2 and 5 or by reaction with the solvent pyridine ( 3 ). In the case of 2 the germatetrazole [Me2Si(NtBu)2]GeN4[Ge(NtBu)2SiMe2]2 ( 6 ) is formed, the tetrazole nitrogens being exclusively substituted by germanium atoms (point symmetry of the molecule Cs(m)). When 1 is treated with 5 a tris(germa)amine [Me2Si(NtBu)2Ge(N3)]3N ( 8 ) is formed, which has an azide group attached to each Ge-atom. X-ray analysis reveals that the nine nitrogen atoms of the azide groups are coplanar with the trigonal planar Ge3N moiety (crystallographic symmetry: 3/m). The reaction of 1 with 3 is very surprising: the pyridine in the product Me2Si(NtBu)2Ge(C5H4N)? N(H)Ge(tBu)(NtBu)2SiMe2 ( 7 ) is bonded via an α-carbon atom while the remaining hydrogen has added to the nitride-nitrogen. 6 crystallizes in the monoclinic system space group C2/m, a = 24.306(9), b = 10.933(6), c = 19.420(9) Å, β = 91.81(2)° and Z = 4. 7 crystallizes in the hexagonal system space group P63/m with a = b = 16.73(1), c = 11.006(8) Å, γ = 120° and Z = 2, and 8 crystallizes in the monoclinic system space group P21/n, a = 11.341(6), b = 26.086(9), c = 13.244(7) Å, β = 98. I2(2)° mit Z = 4. 相似文献
997.
The reaction 40Ca(13C, 12C)41Ca leading to the ground and low-lying ? levels has been studied at bombarding energies of 18.5 and 19.0 MeV, close to the Coulomb barrier. The cross sections have been analysed using the DWBA with previously measured calibrations to obtain the rms radii of 1f and 2p orbits in the 41Ca levels. The rms radius of the 1f point neutron orbit in the ground state relative to the 40Ca core was determined to be 3.89 ± 0.12 fm. This is compared with various theoretical predictions based on Hartree-Fock theory. The 1f orbit radius gives the point neutron excess size to a good approximation for comparison with the value of 3.45 fm deduced from Coulomb energy differences. The consistency of the results with 40Ca(t, d)41Ca experiments using a (t/d), zero-range normalization of 3.26 × 104 MeV2 · fm3 is demonstrated, and trends in neutron size parameters through the Ca isotopes are discussed. 相似文献
998.
M.A. Nasser M.M. Gazzaly J.V. Geaga B. Höistad G. Igo J.B. McClelland A.L. Sagle H. Spinka J.B. Carroll V. Perez-Mendez E.T.B. Whipple 《Nuclear Physics A》1978,312(3):209-216
The p-4He elastic differential cross section has been measured at a kinetic energy of 2.68 GeV. The momentum transfer region studied is t = 0.15–0.66 (GeV/c)2. The cross section displays a shallow first minimum and shape very similar to recent data at 1 GeV. 相似文献
999.
R.C. Greenwood C.W. Reich H.A. Baader H.R. Koch D. Breitig O.W.B. Schult B. Fogelberg A. B?cklin W. Mampe T. Von Egdy K. Schreckenbach 《Nuclear Physics A》1978,304(2):327-428
The level structure of 158Gd has been studied using the prompt γ-rays and conversion electrons emitted following neutron capture in 157Gd. The γ-ray energy and intensity measurements were made using both Ge(Li) detectors and a curved-crystal spectrometer. Conversion-electron energy and intensity measurements were made using two separate magnetic spectrometers: one to measure the primary electron spectrum and the other to measure the lower energy secondary electron spectrum. Some γ-γ coincidence measurements were also made among the secondary γ-rays. From these data, a neutron separation energy of 7937.1 ± 0.5 keV has been determined for 158Gd. A level scheme containing 59 excited states with energies < 2.25 MeV, for which de-excitation modes have been identified, is proposed for 158Gd. Many of these states have been grouped into rotational bands. A total of thirteen excited rotational bands with band-head energies below 2.0 MeV are contained in the level scheme. Features of the proposed level scheme include: the Kπ = 0?, 1? and 2? octupole-vibrational bands with band-head energies of 1263, 977 and 1793 keV, respectively; the γ-vibrational band at 1187 keV; three excited Kπ = 0+ bands with band-head energies of 1196, 1452 and 1743 keV; several two-quasiparticle bands with band-head energies in keV (and Kπ assignments) of 1380 (4+), 1636 (4?), 1847 (1+), 1856 (1?), 1920 (4+) and 1930 (1+). An analysis of (d, p) reaction data is presented which permits definite two-quasiparticle configuration assignments to be made to most of these latter bands. Evidence is presented which suggests strong mixing of some two-neutron and two-proton bands. A phenomenological four-band mixing analysis is made of the energy and E2 transition-probability data for the ground-state band and the three lowest-lying excited collective positive-parity bands. Good agreement with experiment is obtained. A Coriolis-mixing analysis of the octupole bands has been carried out and good agreement with the data on level energies and E1 transition probabilities to the ground-state band has been achieved. Values of Z, the ratio of the E1 transition matrix element with ΔK = 1 to that with ΔK = 0, involving the octupole bands and the first four 0+ bands are derived. For three of these 0+ bands, absolute values of these matrix elements are deduced. An interesting alternation in the sign of Z is observed for these four 0+ bands. 相似文献
1000.
The symplectie shell model, which incorporates vertical major shell configuration mixing as dictated by a quadrupole interaction, is augmented with horizontal (0?ω) mixing induced by realistic single-particle energies and a monopole-pairing interaction. The excitation spectrum and B(E2) rates of the 20Ne ground band are accurately reproduced without the use of an effective charge. The degree of horizontal and vertical mixing is found to be on the order of 20% in the ground state and up to as much as 50% for the 8+ level. 相似文献