Loading...
Search for:
density-transition
0.005 seconds
Effect of lattice relaxation on spin density of nitrogen-vacancy centers in diamond and oscillator strength calculations
, Article European Physical Journal B ; Volume 84, Issue 1 , 2011 , Pages 1-9 ; 14346028 (ISSN) ; Heidari Saani, M ; Ranjbar, A ; Vesaghi, M. A ; Kawazoe, Y ; Sharif University of Technology
2011
Abstract
Using a generalized Hubbard Hamiltonian, many-electron wavefunctions of negatively charged (NV -) and neutral nitrogen-vacancy (NV 0) centers in diamond were calculated. We report the effect of symmetric relaxation of surrounding atoms on the spin density, calculated from the many electron wavefunctions in the ground and excited states. We evaluated the error, that, arises in estimation of spin density when lattice relaxation effect is neglected in Electron Paramagnetic Resonance experiment and showed that the ground state spin density distribution is accessible in outward relaxations. The computed oscillator strengths give a higher efficiency for the 1.945 eV photoluminescence (PL) line of...
Improving the relativistic self-focusing of intense laser beam in plasma using density transition
, Article Physics of Plasmas ; Volume 16, Issue 8 , 2009 ; 1070664X (ISSN) ; Habibi, M ; Yazdani, E ; Sharif University of Technology
2009
Abstract
The propagation of a Gaussian beam in underdense plasma with upward increasing density ramp is analyzed. In this work are shown that the spot size oscillations of laser beam increases and its amplitude shrinks with proper plasma density ramp. This causes the laser beam to become more focused and penetrations deep into the plasma by reduction of diffraction effect. The related focusing parameters are optimized to get the best possible focusing at the relativistic threshold intensity of Nd-glass laser and the effect of the laser intensity in the self-focusing parameters is also investigated. The analytical calculations are presented and showed more reliable results in comparison to the...