The angular correlation of positron-annihilation radiation from a glassy, a partially crystalline and a crystalline Pdo,,75Cuo,06Sio 165 alloy as well as a pure palladium sample was measured. The angular correlation curve for the glassy alloy varies slightly upon crystallization, indicating that the glassy alloy contains negligible vacancy-like defects. The localization of the positron in the glassy state may account for this small change in the angular distribution. The low momentum region of the alloy curves shows an appreciable deviation from that of the free electron model. The observed Fermi momentum of the alloy is larger than that of Pd which agrees qualitatively with the calculated Fermi momentum based on the assumption that the d band of Pd in the alloy is completely filled by valence electrons from Si. The low momentum region of the alloy curve is much higher than that of Pd. The explanation of this is discussed in terms of the increase of the valence electron concentration, the strong association locally between Pd and Si, and the relative positron affinity in the alloy.
This book is concerned with model representations theory of linear non- selfadjoint and non-unitary operators, one of booming areas of functional analysis. This area owes its origin to fundamental works by M.S. Livˇsic on the theory of characteristic functions, deep studies of B.S.-Nagy and C. Foias on the dilation theory, and also to the Lax—Phillips scattering theory. A uni- form conceptual approach organically uniting all these research areas in the theory of non-selfadjoint and non-unitary operators is developed in this book. New analytic methods that allow solving some important problems from the theory of spectral representations in this area of analysis are also presented in this book. The book is aimed at the specialists working in this area of analysis and is accessible to senior math students of universities.
The main object under consideration in the paper is the second derivative operator on a finite interval with zero boundary conditions perturbed by a self-adjoint integral operator with the degenerate kernel (non-local potential). The inverse problem, i.e., the reconstruction of the perturbation from the spectral data, is solved by means of the step-by-step procedure based on the -interlacing property of the spectrum. K E Y W O R D S inverse problem, -interlacing property, non-local potential M S C ( 2 0 1 0 ) 47A45
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