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71.
72.
The Lorentz-weighted average of the S-matrix introduced by G.E. Brown is used in the Feshbach theory of the generalized optical potential to show that the average many-body S-matrix for elastic scattering is exactly equal to the two-body S-matrix of an optical potential. However, the optical potential S-matrix must be evaluated at the complex energy is the half-width of the lorentzian. The resulting equation for the optical phase shifts (OPS) δc, exp , holds even when the level spacing D forces the use of an averaging half-width I > D which is comparable to the energy E, providing that the OPS are also evaluated at the complex instead of being approximated by their values on the real energy axis at E. An appendix discusses briefly the conditions on a potential necessary for the result obtained by Brown that when Lorentz-weighted averaging is used. 相似文献
73.
Michael J. Lacey Colin G. Macdonald Kevin F. Donchi Peter J. Derrick 《Journal of mass spectrometry : JMS》1981,16(8):351-357
Ion currents obtained for fragmentations in a mass spectrometer of reversed geometry have been represented as three-dimensional surfaces, which are termed ‘ion current surfaces’. In addition to ion current, useful dimensions of the ion current surfaces are a parameter ln(|ρ|) where ρ = (V0/V)(E/E0) and a parameter ln(|m*|) where m* = (V0/V)mB. Each ion reaction occurring in the source and flight path gives rise to a pattern of peaks and ridges on the surface. If the major features of the surface corresponding to each ion reaction are projected onto the zero ion current plane, they are disposed in a characteristic trapezoidal pattern. All simple and linked modes of scanning correspond to cross-sections of the surfaces, and representing the scanning modes in this light facilitates the identification of ‘cross-talk’. 相似文献
74.
J. Carroll D.H. Fredrickson M. Goitein B. Macdonald V. Perez-Mendez A. Stetz C.A. Heusch R.V. Kline K.T. Mcdonald 《Nuclear Physics A》1978,305(2):502-508
The reaction was studied at incident proton energies of 377, 462 and 576 MeV. A comparison of our data with others suggests the existence of a sharp forward peak in θHe at 377 and 462 MeV, which is unexplained by the theory and disappears at higher energies. 相似文献
75.
76.
Ion bombardment induced secondary ion and optical excitation from oxide coated Si has been studied as the oxide layer is eroded away. By comparing ion and photon yields, a model for the role of resonant and Auger electron transitions in the neutralisation and de-excitation of the sputtered atoms and ions has been suggested. 相似文献
77.
The influence of various aliphatic diols on the temperature of maximum density (TMD) of water has been investigated. 1,2-Propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 2,5-hexanediol were found to yield positive structural contributions to the solute-induced shift in the TMD, i.e., they are structure makers. Contrariwise, data from the literature indicate that 1,2-ethanediol is a structure breaker. Relationships between the structure making/breaking tendencies of the solutes and the relative positions of the two hydroxyl groups are discussed. 相似文献
78.
Stojanovic MN Semova S Kolpashchikov D Macdonald J Morgan C Stefanovic D 《Journal of the American Chemical Society》2005,127(19):6914-6915
A complete set (YES, NOT, AND, and ANDNOT) of molecular scale logic gates based on ligase deoxyribozymes was constructed. The activity of these gates was visualized through the formation of cascades with downstream phosphodieseterase YES gates, which performed fluorogenic cleavage. 相似文献
79.
80.