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891.
Muon irradiation of pure liquid 3‐chloropropene, CH2=CH-CH2Cl, yields a primary radical, \dot\mboxCH2-CHMu-CH2Cl, and a secondary radical, MuCH2-\rm\dot\mboxCH-CH2Cl. 2‐methyl‐3‐chloropropene yields only the tertiary radical, MuCH2-\rm\dot\mboxC(CH3)-CH2Cl. These three chloroalkyl radicals have been characterized by μSR and μLCR, and the hyperfine coupling constants (hfcs)
have been determined over a range of temperatures, either in the pure liquid precursor or in concentrated solution. The temperature
variation of the hfcs has been analyzed to obtain estimates of the barrier to internal rotation about the C_\alpha-C_\beta
axis for various alkyl groups, and also their minimum energy conformations, i.e. their orientations with respect to the axis
of the 2p_z orbital of the unpaired electron. The tertiary radical is particularly interesting because all three methyl‐like
groups, -CH3,-CH2Cl and -CH2Mu, are represented. The results can be compared to electron spin resonance data for analogous radicals, to provide information
on the effects of Mu substitution for H.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
892.
The Nd:YAG laser-induced breakdown of 20 μm glass microspheres was investigated using time-resolved optical shadow and Schlieren images. Time-resolved imaging showed the location of the initial breakdown and the shockwave motion over its first 400 μm of expansion. Measured shockwave velocities were in the range of 1–10 km/s and showed a linear dependency on laser fluence within 30 ns. 相似文献
893.
A molecular dynamics method has been used to simulate the argon ion-assisted deposition of Cu/Co/Cu multilayers and to explore ion beam assistance strategies that can be used during or after the growth of each layer to control interfacial structures. A low-argon ion energy of 5–10 eV was found to minimize a combination of interfacial roughness and interlayer mixing (alloying) during the ion-assisted deposition of multilayers. However, complete flattening with simultaneous ion assistance could not be achieved without some mixing between the layers when a constant ion energy approach was used. It was found that multilayers with lower interfacial roughness and intermixing could be grown either by modulating the ion energy during the growth of each metal layer or by utilizing ion assistance only after the completion of each layers deposition. In these latter approaches, relatively high-energy ions could be used since the interface is buried and less susceptible to intermixing. The interlayer mixing dependence upon the thickness of the over layer has been determined as a function of ion energy. 相似文献
894.
A. N. W. Hone 《Transactions of the American Mathematical Society》2007,359(10):5019-5034
The Somos 5 sequences are a family of sequences defined by a fifth order bilinear recurrence relation with constant coefficients. For particular choices of coefficients and initial data, integer sequences arise. By making the connection with a second order nonlinear mapping with a first integral, we prove that the two subsequences of odd/even index terms each satisfy a Somos 4 (fourth order) recurrence. This leads directly to the explicit solution of the initial value problem for the Somos 5 sequences in terms of the Weierstrass sigma function for an associated elliptic curve.
895.
896.
897.
M. Bijak-Zochowski A. M. Waas W. J. Anderson C. E. Miniatt 《Experimental Mechanics》1991,31(3):271-275
The photoelastic method is used to investigate the possibility of relieving the large local stresses that develop in the corners of a right angled indenter compressing a semi-infinite body by inducing geometric changes to the indenter/semi-infinite body configuration. It is shown that a circular notch cut along the free edges of the indenter can totally eliminate the large corner stresses. The notch, if placed along the interface edge of the half plane, can reduce the stress concentration, but never eliminate it. The results obtained have wide practical application. 相似文献
898.
899.
900.
N. M. Agababyan M. R. Atayan M. Charlet J. Czyżewski E. A. De Wolf K. Dziunikowska A. M. F. Endler Z. Sh. Garutchava H. R. Gulkanyan R. Sh. Hakobyan J. K. Karamyan D. Kisielewska W. Kittel S. S. Mehrabyan Z. V. Metreveli E. C. Oliveira K. Olkiewicz F. K. Rizatdinova E. K. Shabalina L. N. Smirnova M. D. Tabidze L. A. Tikhonova A. V. Tkabladze A. G. Tomaradze F. Verbeure S. A. Zotkin 《Zeitschrift fur Physik C Particles and Fields》1996,71(1):405-414
The NA22 data onπ ? π ? correlations are analyzed in terms of a number of two- and three-dimensional parametrizations (Gaussian space-time, Goldhaber, Bowler string-like, Bertsch hydrodynamical, Kopylov-Podgoretskii, etc.). Contrary to the results obtained for e+e? andµp collisions, the Goldhaber parametrization, as well as string-like models, fail in describing the hadron-hadron data. Better fits are obtained in the framework of surface-emitting fireball-like models, both when including and excluding hydrodynamical expansion of nuclear matter. Our results indicate that pion radiation occurs at earlier stages of matter evolution than in nuclear collisions. 相似文献