Coherence parameters for electron capture in H⁺+He collisions

Abstract

The classical trajectory Monte Carlo method is used to calculate coherence parameters for electron capture to H(n=2, 3 and 4) in 30 to 250 keV H++He collisions. The parameters evaluated are the x- and z-components of the dipole moment (D) and the z-component of the perihelion velocity of the captured election (L*A). The calculated integral values are found to be in reasonable agreement with available experimental results. Components of the dipole moment and (L*A) were also evaluated as a function of projectile scattering angle. Here, rapid variations of the parameters are observed near the Thomas angle that indicate the transition from the hard, large angle collisions between the projectile and target nucleus to the soft, small angle scattering between the projectile and active electron.

A Study on IR Light Intensities Scattered from Defects in an Indum-Doped Liquid Encapsulated Czochralski GaAs Crystals as Functions of Wavelength and Intensity of Bias Light Superposed on the Defects

“…For energies above about 50 keV, results of the classical trajectory Monte Carlo (CTMC) approach [20] agree reasonably well with our results in trend and magnitude, but differ below that energy. While agreeing in the general shape, the CDW [15] calculations differ greatly in magnitude from our results and from those of the experiments throughout the range.…”

“…Theoretical data: ---CTMC [20], -· -AOCC of Shingal and Lin [17], · · · · · · CDW [15], and open circles connected by a solid line show the present results. [12], • Cline et al [14] and Hippler et al [13].…”

“…Interest in these descriptors of the charge transfer process have been the subject of carefully constructed experimental measurements and serve as a very strenuous test of theoretical treatments. Existing experimental studies cover a wide range of impact energy [12][13][14], and there are many theoretical results based on various techniques [15][16][17][18][19][20]. We note that discrepancies between the existing theoretical results for this problem remain unresolved.…”

Orientation effects for collisions at energies beyond the `velocity-matching' region

“…For example, a few years ago Toshima and Lin [11] found disagreements between CTMC and atomic orbital closecoupling (AOCC) calculations for some coherence parameters in hydrogenic collision systems. However, Lundy et al [12] obtained excellent agreement between CTMC calculations and experiments for H + -He collisions. Another much discussed topic has been the validity of simple models like velocity-matching [13] and propensity rules for Unité de Recherche Associée au CNRS, URA 176.…”

Left/right capture asymmetry in He2+-Na(3p-1) collisions: classical versus quantal collision dynamics

“…Thus total and state-to-state asymmetries in differential scattering may now be studied and compared to theory at the most fundamental level of one-electron quantum dynamics. Since the classical trajectory Monte Carlo (CTMC) method has been used with various degrees of success for many such related studies also involving ionization [3][4][5][6][7], one may ask whether there are any distinct quantum signatures at all involved in the collision dynamics. Our previous studies of collisions between singly charged ions and excited atoms have displayed, however, some clear discrepancies for electron capture.…”