Anisotropic collisional relaxation of excited hydrogen atoms

Journal Article · Sat Apr 01 04:00:00 EST 1995 · Optics and Spectroscopy

OSTI ID:223793

Petrashen`, A G; Rebane, V N; Rebane, T K ^[1]

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1. St. Petersburg State Univ. (Russian Federation)

Polarization phenomena observed in anisotropic collisions of excited hydrogen atoms with a beam of low-energy charged particles (protons) are studied theoretically. Polarization moments of a set of excited states of hydrogen atoms with a principal quantum number n = 2 are classified by irreducible representations of the symmetry group of the collisional problem taking into account the energy level degeneracy in the orbital quantum number 1. It is shown that the joint anisotropic collisional relaxation of the 2s state and three Zeeman sublevels of the 2p state is determined by the relaxation of 16 components of six polarization moments, including both diagonal and nondiaconal moments with respect to 1, and is described by 20 independent effective cross sections. The effective cross sections are calculated as functions of the proton velocity by computer solution of a system of the equation of the method of the impact parameter with allowance for particle trajectory bending. The results are applied to an investigation of deexcitation of the metastable 2s state (with a lifetime of 0.12 s) in collisions with a proton beam accompanied by a transition to the 2p state (with a lifetime of 1.6 x 10{sup -9}s) and subsequent emission of light, The alignment signal of the 2p state populated and aligned by collisions and the degree of linear polarization of the 2p-1s {alpha}-line of the Lyman series are calculated. In the maximum of the alignment signal, the degree of polarization reaches 60% (with the largest linear polarization along a proton beam) and is sufficient for detecting fluxes of charged particles in laboratory and astrophysical objects by measurements of the polarization of the Lyman {alpha}-line.

• OSTI ID: 223793
• Journal Information: Optics and Spectroscopy, Journal Name: Optics and Spectroscopy Journal Issue: 4 Vol. 78; ISSN OPSUA3; ISSN 0030-400X
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ANISOTROPY
CROSS SECTIONS
EXCITED STATES
HYDROGEN
ION-ATOM COLLISIONS
PROTONS
RELAXATION