ANGULAR MOMENTUM CHANGING TRANSITIONS IN PROTON-RYDBERG HYDROGEN ATOM COLLISIONS

被引:22
|
作者
Vrinceanu, D. [1 ]
Onofrio, R. [2 ,3 ]
Sadeghpour, H. R. [3 ]
机构
[1] Texas So Univ, Dept Phys, Houston, TX 77004 USA
[2] Univ Padua, Dipartimento Fis & Astron Galileo Galilei, I-35131 Padua, Italy
[3] Harvard Smithsonian Ctr Astrophys, ITAMP, Cambridge, MA 02138 USA
来源
ASTROPHYSICAL JOURNAL | 2012年 / 747卷 / 01期
基金
美国国家科学基金会;
关键词
atomic processes; cosmic background radiation; planetary nebulae: general; stars: atmospheres; stars: early-type; CHARGED-PARTICLES; STATES; IONS; RECOMBINATION; EQUILIBRIUM; POPULATIONS; NEBULAE;
D O I
10.1088/0004-637X/747/1/56
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Collisions between electrically charged particles and neutral atoms are central for understanding the dynamics of neutral gases and plasmas in a variety of physical situations of terrestrial and astronomical interest. Specifically, redistribution of angular momentum states within the degenerate shell of highly excited Rydberg atoms occurs efficiently in distant collisions with ions. This process is crucial in establishing the validity of the local thermal equilibrium assumption and may also play a role in determining a precise ionization fraction in primordial recombination. We provide an accurate expression for the non-perturbative rate coefficient of collisions between protons and H(nl) ending in a final state H(nl'), with n being the principal quantum number and l, l' the initial and final angular momentum quantum numbers, respectively. The validity of this result is confirmed by results of classical trajectory Monte Carlo simulations. Previous results, obtained by Pengelly and Seaton only for dipole-allowed transitions l -> l +/- 1, overestimate the l-changing collisional rate coefficients approximately by a factor of six, and the physical origin of this overestimation is discussed.
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页数:7
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