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101.
Thermochemistry and Structure of Beryllium Chloride BeCl2 is dimorphous, with a transition point at 405°C. The transition enthalpy and transition entropy have been determined by solution calorimetry: ΔUH° = 2.9 kJmol?1 and ΔUS° = 9.7 JK?1mol?1. The previously known SiS2-type structure of BeCl2 is that of the high temperature phase. The structure of the phase stable at room temperature has been determined from single crystal data. a = 1 062.4(6) pm, c = 1 804(2) pm, I41/acd, Z = 32, R = 0.038 (Mg(NH2)2-type). The structure consists of P4O10-like [Be4Cl6Cl4/2]-units, connected by their terminal anions. 相似文献
102.
Manfred Fink 《Physik in unserer Zeit》1995,26(3):129-137
103.
D. Fink R. Klett C. Mathis J. Vacik V. Hnatowicz L. T. Chadderton 《Applied Physics A: Materials Science & Processing》1996,62(3):191-195
Standard porcelain samples burnt at different temperatures were doped with LiCl, organo-Li solutions, or with fullerene solution and then dried. The depth profiles of both Li and fullerene were determined. The distributions of the incorporated dopants strongly depend on the samples' porosity. Additional ultrasonic treatment during the diffusion process has a fatal influence on the porcelain structure, resulting in enhanced dopant uptake of the remaining sample. The surface-near shape of the depth profiles is interpreted by solvation, i.e., by precipitation of the dissolved salts or fullerenes in the surface-near zone during the drying process. It is shown that the solvation effect is important only in the case of media with high porosity. 相似文献
104.
D. Fink Huanwen Hu R. Klett M. Müller J. Zhu Changlin Li Yonme Sun Feng Ma Lihong Wang 《Radiation measurements》1995,25(1-4):51-54
Non-overlapping as well as overlapping tracks of energetic ions have been introduced into polyimide foils. After aging their conductivity was measured. This — to our knowledge — first systematic study shows that conductivity does not only result from multiple track overlapping, but can be found already in single ion tracks. This conductivity is shown to be primarily a consequence of electronic energy transfer. The conductivity of single ion tracks is higher than that of typical insulators, but still orders of magnitude lower than that of typical semiconductors. The conductivity is independent of the applied electric field strength until at excessive voltages the electric current increases nonlinearly up to complete breakthrough. The total conductivity of an irradiated polyimide foil increases proportionally with ion fluence for large ion track spacings, and approaches saturation when the electronically active track regimes begin to overlap. Above some thousand times track overlapping however, new chemical and structural changes in the irradiated material lead to another strong increase in conductivity. 相似文献
105.
D. W. Nix J. C. McGeorge R. W. Fink 《Zeitschrift für Physik A Hadrons and Nuclei》1972,256(2):131-137
MeanL-shell x-ray fluorescence yields \((\bar \omega _L )\) have been measured by observingK andL x-ray spectra emitted in the decay of109Cd,145Pm, and153Gd with a high resolution Si(Li) x-ray detector. The results forZ=47, 60, and 63 are as follows: \(\bar \omega _L \) =0.0425±0.0064, 0.131±0.017, and 0.142±0.023, respectively. Additional values of \(\bar \omega _L \) from this laboratory atZ=55, 56, 57, 59, and 65 are also tabulated as are previous experimental values atZ=47, 60, and 63. For comparison, theoretical estimates of \(\bar \omega _L \) were computed using theoreticalL-subshell fluorescence and Coster-Kronig yields, together with subshell vacancy distributions calculated from the literature. The theoretical estimates atZ=47, 60, and 63, based on the subshell calculations of Chen, Crasemann, and Kostroun, agree well with experiment. 相似文献
106.
107.
J. F. Fink M. S. Jacobson L. F. Kinch J. Roberts 《Periodica Mathematica Hungarica》1985,16(4):287-293
In this paper we present a characterization of connected graphs of order 2n with domination numbern. Using this class of graphs, we determine an infinite class of graphs with the property that the domination number of the product of any two is precisely the product of the domination numbers. 相似文献
108.
The L1 subshell orbital electron capture probability PL1 in the decay of 33.4 y 207Bi to the 2339.89 keV level in 207Pb is measured to be 0.518 ± 0.081 (95% confidence) by a new method in which L1 subshell characteristic X-rays in the Lγ X-ray peak are observed in an Xγt coincidence mode with 1770.23 keV γ-rays. The value of PL2is 0.047 ± 0.015 (95% confidence). From these results a value of QEC = 39-8+21 keV is obtained for capture transitions to the 2339.89 keV level. The absence of K-capture to this level also is established by absence of K X-rays in coincidence with 1770.23 keV γ-rays. 相似文献
109.
110.
R. Klett D. Fink M. Mü ller H. Omichi F. Hosoi V. Hnatowicz J. Vacik G. Sanchez 《Radiation measurements》1997,28(1-6):51-53
Usually ion tracks are studies ex-situ, i.e. after removal of the ion-irradiated sample from the evacuated irradiation vessel. The exposure to ambient air leads to degradation effects which are frequently neglected and consequently have been studied rarely. They have never been explained consistently. In this work we compile and discuss them in the frame of today's general understanding of ion tracks in polymers. It appears that some pristine polymers such as polyethylene are covered by a surface layer which is badly permeable for gaseous contaminants. Ion irradiation leads to destruction of this protective layer so that oxygen and moisture from the ambient air can easily penetrate through the ion tracks, and eventually even into the surrounding pristine material. Moisture absorption along the tracks gives rise to some faint conductivity. Oxygen uptake adds new trapping centers to the existing ones along the tracks, so that on one hand an increased dopant uptake capability is recorded, and on the other hand oxygen-sensitive mobile dopants are immobilized along the ion tracks. Photooxidation processes contribute to the fading of the optical blackening of irradiated polymers. 相似文献