Electron capture in collisions of H(+) ions with S atoms and its reverse process below keV-energies

Abstract

The potential curves and nonadiabatic coupling matrix elements for the HS(+) system were obtained from multireference single and double excitation configuration interaction calculations employing a relatively large basis set. A semiclassical molecular orbital expansion method with a straight line trajectory of the incident ion was employed to study the collision dynamics below 10 keV. A set of first order coupled equations was solved numerically to obtain scattering amplitudes for transitions. The molecular states included for the H + S(+)(quadruplet-S) collision system are H + S(+)(quadruplet-S) for the initial, H(+) + S(triplet-P) for charge transfer, and H + S(+)(doublet-D) for excitation. The spin averaged electron capture cross section from the ground state S(triplet-P) atoms by H(+) impact was illustrated. Both electron capture cross sections to H + S(+)(doublet-P) and H + S(+)(doublet-D) states increased rapidly as the collision energy increases from 10 eV, with a slightly larger magnitude for H + S(+)(doublet-P) formation.

比較的大きい基底関数系を用いた多重基準1重および2重励起配置間相互作用計算によりHS(+)系のポテンシャル曲線と非断熱結合行列要素を求めた。入射イオンの直線軌道をもつ半古典的分子軌道展開法を用いて10keV以下の衝突力学を調べた。遷移のための散乱振幅を得るために1組の1次連立方程式の数値解を求めた。H+S(+)(4重項-S)衝突系に含まれる分子状態は初期状態に対するH+S(+)(4重項-S)、電荷移動に対するH(+)+S(3重項-P)、および励起状態に対するH+S(+)(2重項-D)である。H(+)衝突による基底状態S(3重項-P)原子からのスピン平均電子捕獲断面積を図示した。H+S(+)(2重項-P)およびH+S(+)(2重項-D)に対する電子捕獲断面積は衝突エネルギーが10eV以上になると急激に増大した。それと同時にH+S(+)(2重項-P)の生成が若干増大した。