Charge-state dependence of binary-encounter-electron cross sections and peak energies

Journal Article · Tue Nov 30 23:00:00 EST 1993 · Physical Review A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.48.4421· OSTI ID:5800021

Hidmi, H I; Richard, P; Sanders, J M; Schoene, H; Giese, J P; Lee, D H; Zouros, T J.M.; Varghese, S L ^[1]

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1. J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States)

The charge-state dependence of the binary-encounter-electron (BEE) double-differential cross section (DDCS) at 0[degree] with respect to the beam direction resulting from collisions of 1 MeV/amu H[sup +], C[sup [ital q]+], N[sup [ital q]+], O[sup [ital q]+], F[sup [ital q]+], Si[sup [ital q]+], and Cl[sup [ital q]+], and 0.5 MeV/amu Cu[sup [ital q]+] with H[sub 2] is reported. The data show an enhancement in the BEE DDCS as the charge state of the projectile is decreased, in agreement with the data reported by Richard [ital et] [ital al]. [J. Phys. B 23, L213 (1990)]. The DDCS enhancement ratios observed for the three-electron isoelectronic sequence C[sup 3+]:C[sup 6+], N[sup 4+]:N[sup 7+], O[sup 5+]:O[sup 8+], and F[sup 6+]:F[sup 9+] are about 1.35, whereas a DDCS enhancement of 3.5 was observed for Cu[sup 4+]. The BEE enhancement with increasing electrons on the projectile has been shown by several authors to be due to the non-Coulomb static potential of the projectile and additionally to the [ital e]-[ital e] exchange interaction. An impulse-approximation (IA) model fits the shape of the BEE DDCS and predicts a [ital Z][sub [ital p]][sup 2] dependence for the bare-ion cross sections. The IA also predicts a binary peak energy that is independent of [ital q] and [ital Z][sub [ital p]] and below the classical value of 4[ital t], where [ital t] is the energy of electrons traveling with the projectile velocity. We observed a BEE energy shift [Delta][ital E] ([Delta][ital E]=4[ital t][minus][ital E][sub peak], where [ital E][sub peak] is the measured energy at the peak of the binary encounter electrons) that is approximately independent of [ital q] for the low-[ital Z][sub [ital p]] ions, whereas the measured [Delta][ital E] values for Si, Cl, and Cu were found to be [ital q] dependent.

• OSTI ID: 5800021
• Journal Information: Physical Review A; (United States), Journal Name: Physical Review A; (United States) Vol. 48:6; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

664300* -- Atomic & Molecular Physics-- Collision Phenomena-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
BINARY ENCOUNTER METHOD
CALCULATION METHODS
CARBON IONS
CATIONS
CHARGE STATES
CHARGED PARTICLES
CHLORINE IONS
COLLISIONS
COPPER IONS
CORRELATIONS
CROSS SECTIONS
DIFFERENTIAL CROSS SECTIONS
ELECTRON LOSS
ELEMENTS
ENERGY RANGE
FLUORINE IONS
HYDROGEN
HYDROGEN IONS
HYDROGEN IONS 1 PLUS
IMPACT PARAMETER
ION COLLISIONS
ION-MOLECULE COLLISIONS
IONS
MEV RANGE
MEV RANGE 01-10
MOLECULE COLLISIONS
MULTICHARGED IONS
NITROGEN IONS
NONMETALS
OXYGEN IONS
SILICON IONS