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1.
3-Methyl-2-butenenitrile (1) cyclodimerised on treatment with lithium diisopropylamide in dimethoxyethane at temperatures between ?78°C and 0°C to 3-amino-4-cyano-1,5,5-trimethyl-1,3-cyclohexadiene (2) the structure of which was established by acid hydrolysis to the known 4-cyano-1,5,5-trimethyl-1-cyclohexene-3-one (3). 相似文献
2.
J. Bainbridge D.A. Channing W.H. Whitlow R.E. Pendlebury 《Journal of Physics and Chemistry of Solids》1973,34(9):1579-1586
Mössbauer spectra of ξ-Fe2N at 4·2°K, 78°K and room temperature are presented. The Mössbauer parameters are compatible with the nitrogen donor model previously found to be applicable to the lower iron nitrides. X-ray analyses of this phase confirm the structure previously reported. Mössbauer and X-ray spectra for partially nitrided iron foils containing γ′, ε and ξ iron nitrides are also discussed. 相似文献
3.
M.H. Majles Ara SR. Hosseini M.H. Rezvani M. Abolhassani 《Journal of Physics and Chemistry of Solids》2011,72(11):1367-1372
In this paper, the parametric scattering of a single extraordinary polarized beam of laser in BaTiO3 photorefractive crystal has been investigated experimentally and theoretically. The resulting pattern consists of beam fanning, isotropic ring, and anisotropic one. Among all parts of scattering pattern, isotropic ring has not been studied as much as beam fanning and anisotropic ring, and there still are some differences in reports about it. Therefore, the study has mainly focused on this part. In this experimental configuration, isotropic ring is just visible in positive angles although the other parts of parametric scattering pattern can be visible from behind and in front of the crystal. In addition to steady state pattern in forward and backward directions, its transient behavior with the rotation of crystal has been studied. The results of experiments have been analyzed carefully, and their theoretical explanations have been presented based on the standard theory of parametric scattering in photorefractive crystals. It has been shown that this configuration corresponds to the so called parametric B-process scattering. 相似文献
4.
V. E. Varlamov V. V. Nesvizhevskii A. P. Serebrov R. R. Tal’daev A. G. Kharitonov P. Geltenbort Ts. Ts. Panteleev A. V. Strelkov V. N. Shvetsov M. Pendlebury K. Schreckenbach 《Journal of Experimental and Theoretical Physics》1998,87(3):426-432
The temperature dependence of the loss factor for ultracold neutrons owing to heating at thermal energies on the surface of
a beryllium sample is studied. The probability of heating ultracold neutrons is anomalously high throughout the entire measured
temperature interval, but especially at low temperatures.
Zh. éksp. Teor. Fiz. 114, 786–797 (September 1998) 相似文献
5.
Observation of the penetration of subbarrier ultracold neutrons through beryllium foils and coatings
V. E. Varlamov V. V. Nesvizhevskii A. P. Serebrov R. R. Tal’daev A. G. Kharitonov P. Geltenbort M. Pendlebury A. V. Strelkov V. N. Shvetsov K. Schreckenbach 《JETP Letters》1997,66(5):336-343
The subbarrier passage of ultracold neutrons through beryllium foils and coatings with a probability much higher than that
of tunneling is observed. This effect may be responsible for the so-called anomalous loss of ultracold neutrons.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 5, 317–322 (10 September 1997) 相似文献
6.
S. S. Arzumanov L. N. Bondarenko E. I. Korobkina V. I. Morozov Yu. N. Panin A. I. Fomin S. M. Chernyavskii S. V. Shilkin P. Geltenbort W. Drexel J. Pendlebury K. Schreckenbach 《JETP Letters》1997,65(1):1-6
The subbarrier reflection of ultracold neutrons (UCNs) from stainless steel (an alloy of iron, nickel, chromium, and titanium)
is investigated by means of neutron-radiation analysis. It is found that the increase in the probability of capture of UCNs
by nuclei is large compared to the standard theory. The effect is selective, the enhancement factor varying From 3 for iron
to 90 for titanium.
Pis’ma Zh. éksp. Teor. Fiz. 65, No. 1, 3–8 (10 January 1997) 相似文献
7.
P. Geltenbort V. V. Nesvizhevsky D. G. Kartashov E. V. Lychagin A. Yu. Muzychka G. V. Nekhaev V. N. Shvetsov A. V. Strelkov A. G. Kharitonov A. P. Serebrov R. R. Tal’daev J. M. Pendlebury 《JETP Letters》1999,70(3):170-175
A surprising new escape channel for ultracold neutrons (UCNs) in traps was reported recently. It could be relevant to the
long-standing puzzle of the “too high” loss rate of UCNs from traps, which has yet to be completely understood and eliminated.
In the present work we positively identify the new phenomenon and investigate it in detail. The escape of UCNs from traps
is due to rare events in which their energy undergoes a small increase (∼10−7 eV). The reason for such an energy gain and its impact on the physics of UCN storage is still to be investigated.
Pis’ma Zh. éksp. Teor. Fiz. 70, No. 3, 175–180 (10 August 1999)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
8.
S. S. Arzumanov S. T. Belyaev L. N. Bondarenko S. M. Ivanov E. I. Korobkina A. N. Lyubimov V. I. Morozov A. I. Ryazanov Yu. N. Panin A. I. Fomin S. M. Chernyavskii P. Geltenbort J. Pendlebury K. Schreckenbach 《Journal of Experimental and Theoretical Physics》1999,88(1):72-78
Neutron-radiation analysis is used to investigate the subbarrier reflection of ultracold neutrons from the surface of a titanium-stabilized
Fe-Ni-Cr stainless steel. A significant selective increase in the probability of neutron capture by nuclei of the medium in
comparison to theory is discovered. An explanation is given for the effect, which is associated with the existence of titanium-containing
clusters and structural defects that distort the form of the distribution of the effective interaction potential between ultracold
neutrons and the material surface.
Zh. éksp. Teor. Fiz. 115, 126–140 (January 1999) 相似文献
9.
MA Freitas SR Dillon RC Dougherty AG Marshall 《Rapid communications in mass spectrometry : RCM》1999,13(15):1622-1625
The self-chemical ionization of diethylzinc is examined by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry and semiempirical molecular orbital calculations. Electron impact of diethylzinc neutral produces the radical cation, C(4)H(15)Zn(+) (m/z x 122), which reacts further with the neutral (C(2)H(5))(2)Zn to give the following product ions: Zn(+) (m/z x 64), C(2)H(5)Zn(+) (m/z x 93), C(4)H(9)Zn(+) (m/z x 121), C(4)H(11)Zn(2)(+) (m/z x 187), and C(6)H(15)Zn(2)(+) (m/z x 215). To determine the structure and pathways for production of these ions, monoisotopic (12)C(4)H(15)(64)Zn(+), (64)Zn(+) and (12)C(2)H(5)(64)Zn(+) were individually isolated and reacted with the neutral background. We also performed semiempirical molecular orbital calculations (ZINDO/1). The molecular orbital calculations and experimental data are consistent in predicting that the ethyl group on the diethylzinc cation carries the positive charge. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
10.
W. Schott J.M. Pendlebury I. Altarev S. Gröger E. Gutsmiedl F.J. Hartmann S. Paul G. Petzoldt P. Schmidt-Wellenburg U. Trinks 《The European Physical Journal A - Hadrons and Nuclei》2003,16(4):599-601
Ultra-cold neutrons (UCN) are produced in superfluid helium by single- and multi-phonon excitation. The UCN production rate
density R
II via multiphonons can be larger than that by one-phonon excitation R
I being due to the dependence of the incident neutron spectral flux density dφ/dλ on the wavelength λ.
Received: 28 March 2002 / Accepted: 19 December 2002 / Published online: 11 March 2003
RID="a"
ID="a"e-mail: wschott@e18.physik.tu-muenchen.de
RID="b"
ID="b"On leave of absence from PNPI, Gatchina, Russia
Communicated by T. Walcher 相似文献