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151.
K. -H. Speidel V. Mertens W. Trölenberg M. Knopp H. Neuburger K. Bharuth-Ram J. Gerber 《Zeitschrift für Physik A Hadrons and Nuclei》1984,315(3):319-323
The transient field technique has been used to determine theg-factor of the 4 2 + state at 6.010MeV excitation in24Mg. The deduced value ofg=+0.5(4) is consistent with collective model expectations. Further, the equality within experimental accuracies, of the g-factors of the 2 1 + , 2 2 + , 4 1 + and 4 2 + states agrees with theoretical predictions for thisT=0 self-conjugate nucleus, in contrast to the results for20Ne. 相似文献
152.
G. J. Kumbartzki K. Hagemeyer W. Knauer G. Krösing R. Kuhnen V. Mertens K. -H. Speidel J. Gerber W. Nagel 《Hyperfine Interactions》1979,7(1):253-264
PAC measurements on the 4.43 MeV12C(2+) state on recoil in magnetized iron at velocitiesv
ion=2.1v
0, 6.0v
0, 7.4v
0 yield integral precession angles of =+0.72(18), +0.94(16) and +0.71(18) mrad, respectively. The results supplementary to existing precession data are interpreted by a distribution of C5+ ions implying a K-shell polarization of 28% and an effective charge larger than measured after emergence from the solid. The low-velocity precession tends to disagree with the empirical law of linear relationship between transient field and ion velocity. The presence of molecular orbital effects is discussed. 相似文献
153.
The constant-amplitude solutions with wavelength of a semiclassical laser model exhibit three different instabilities in the (, )-plane for pumpparameters above threshold. 相似文献
154.
The reaction of AgSCN with (Me3PhN)3[Fe(NCS)6] in DMF yields two‐dimensional polymeric, heteronuclear complexes (Me3PhN)2[Ag2Fe(SCN)6] ( 1 ) and (Me3PhN)6[Ag6Fe3(SCN)18] · CH2Cl2·DMF ( 2a ) with bridging SCN? ligands, whereas additional (Me3PhN)(SCN) leads to (Me3PhN)4[Ag2Fe(SCN)8] ( 3 ) with a one‐dimensional structure. The selenocyanato complex 2b , homologous to 2a , could also be prepared. Single crystal X‐ray structure determinations show, that the Ag+ ions in 1 and 2a are coordinated tetrahedrally by four S atoms, in 3 by one N and three S atoms of the bridging SCN? ligands; six N atoms of the SCN? or SeCN? ligands bind to Fe2+ in an octahedral arrangement. 相似文献
155.
Z-Protected diphenyl (decarboxy-dipeptidyl)phosphonates 5a - c with a (decarboxysarcosinyl)phosphonate moiety are prepared from Z-L-alanine ( 1a ). Z-L-valine ( 1b ), and Z-L-phenylalanine ( 1c ) by the following series of steps: coupling with methyl sarcosinate (→ 2a – c ), saponification (→ 3a – c ), Hofer-Moest oxidative decarboxyiation by electrolysis in MeOH (→ 4a – c ), and Arbuzov reaction with P(OPh)3/TiCl4 (Scheme 3). Double deprotonation and alkylation lead to non-stereoselective incorporation of side chains next to the phosphonate group (products of type 6 – 8 , nine examples, see Scheme 4). In the cases of 6a – c and 8c , the diastereoisomers could be separated and the configuration of the newly formed stereogenic center deduced. We assign the L,D-configuration to the diastereoisomers for which the 31 P-NMR signal appears at higher field. 相似文献
156.
A. Werner T. Grune W. Siems W. Schneider H. Shimasaki H. Esterbauer G. Gerber 《Chromatographia》1989,28(1-2):65-68
Summary The analysis of two metabolite groups, nucleotides and aldehydes, is necessary for assessment of oxygen radical metabolism during hypoxia and reoxygenation.Nucleotides and their derivatives were determined by HPLC using gradient elution with 10 mM NH4H2PO4 buffer containing 2 mM t-butylammoniumphosphate and acetonitrile.Aldehydes occuring after lipid peroxidation were analyzed by derivatisation to dinitrophenylhydrazones followed by TLC and HPLC separation with methanol/water on an ODS column. 相似文献
157.
A numerical method is given for the determination of the scattering amplitude, hence all the phase shifts, from the differential cross section at fixed energy. To obtain the phase of the scattering amplitude, the unitarity equation of scattering theory is solved, using the (experimental) cross section as input information. A straightforward iterative approach diverges for atom—atom input data, thus an appropriately modified method of solution is introduced to overcome this difficulty. The method was applied to two test cases, in both of which calculated atom—atom cross sections were used as simulated input data. Convergence to the correct phase was obtained in both examples, starting in each case with a guess phase function that differed considerably from the true solution. Convergence cannot be obtained, however, from an extremely poor starting phase. This study shows that the scattering amplitude for atomic scattering at thermal energies can be determined systematically, without use of parametrized functions, if a sufficiently accurate experimental cross section is available. A subsequent article describes a quantum mechanical procedure whereby the interaction potential can be constructed from the determined scattering amplitude. 相似文献
158.
Structure of a monoclinic polymorph of N-[4-(acetyloxy)-phenyl]acetamide, a prodrug of acetaminophen
The preparation, single crystal x-ray structure and the computed powder XRD pattern of a monoclinic polymorph of N-[4-(acetyloxy)phenyl]acetamide, a prodrug of acetaminophen, are reported. The polymorph crystallizes in the space group P21/n with Z = 4 and unit cell dimensions a = 7.219(2), b = 8.015(2), c = 16.575(2) Å, = 92.07(1)°, and V = 958.4(4) Å3. Infinite spiral molecular arrays result from intermolecular head-to-tail hydrogen bonding between the amidic H atom of one molecule and the acetoxy carbonyl oxygen atom of a 21-related molecule. 相似文献
159.
Annemè Boyce Thomas I. A. Gerber Eric C. Hosten 《Journal of chemical crystallography》2018,48(3):96-102
The reaction of the potentially bidentate ambidentate N,O-donor ligands 3-hydroxy-2-pyridinecarboxylic acid (Hhpc) and 3-hydroxy-2-(hydroxymethyl)pyridine (Hhhp) with trans-[ReOCl3(PPh3)2] led to the isolation of the products [ReOCl(hpc)2] (1) (from acetonitrile) and [ReOCl2(hhp)(PPh3)] (2) (from ethanol) respectively. In both complexes hpc and hhp are coordinated as bidentate N,O-donor chelates, rather than as O,O-donor ligands. From the reaction of [Re(CO)5Cl] and Hhhp·HCl in ethanol the neutral complex fac-[Re(CO)3Cl(Hhhp)] (3) was obtained, with N,O-coordination of Hhhp. Complex 1 crystallizes in the monoclinic space group P21/n with a?=?6.8782(3), b?=?20.0647(8), c?=?10.8692(4) Å, β?=?107.545(1)°, and Z?=?4. Complex 2 crystallizes in the triclinic space group P-1 with a?=?7.3523(4), b?=?8.1047(5), c?=?19.591(1) Å, α?=?91.133(2)°, β?=?93.656(2)°, γ?=?93.074(2)° and Z?=?2. Complex 3 has monoclinic P21/c symmetry with the cell parameters a?=?10.6452(5), b?=?11.1372(5), c?=?9.7229(5) Å, β?=?106.107(2)°, and Z?=?4. 相似文献
Graphical Abstract
The reaction of the potentially bidentate ambidentate N,O-donor ligands 3-hydroxy-2-pyridinecarboxylic acid (Hhpc) and 3-hydroxy-2-(hydroxymethyl)pyridine (Hhhp) with trans-[ReOCl3(PPh3)2] led to the isolation of the products [ReOCl(hpc)2] (from acetonitrile) and [ReOCl2(hhp)(PPh3)] (from ethanol) respectively. In both complexes hpc and hhp are coordinated as bidentate N,O-donor chelates, rather than as O,O-donor ligands. From the reaction of [Re(CO)5Cl] and Hhhp·HCl in ethanol the neutral complex fac-[Re(CO)3Cl(Hhhp)] was obtained, with N,O-coordination of Hhhp. Spectroscopic data and the X-ray crystal structures of the complexes are reported.160.
T. Brixner A. Oehrlein M. Strehle G. Gerber 《Applied physics. B, Lasers and optics》2000,70(7):S119-S124
We describe the experimental implementation of feedback-optimized femtosecond laser pulse shaping. A frequency-domain phase shaper is combined with different pulse characterization methods and appropriate optimization algorithms to compensate for any phase deviation. In particular, bandwidth-limited, amplified laser pulses are achieved by maximizing the second-harmonic generation (SHG) of the shaped laser pulses with the aid of an evolutionary algorithm. Real-time measurement of the absolute phases is achieved with spectral interferometry where the reference pulse is characterized by FROG, the so-called TADPOLE method. Using the complete electric field as feedback, arbitrary laser pulse shapes can be optimally generated in two different ways. First, a local convergence algorithm can be used to apply reliable and accurate spectral chirps. Second, an evolutionary algorithm can be employed to reach specific temporal profiles. 相似文献