Binary And Ternary Recombination Of H3\u3csup\u3e+\u3c/sup\u3e And D 3\u3csup\u3e+\u3c/sup\u3e Ions With Electrons In Low Temperature Plasma

Measurements of recombination rate coefficients of binary and ternary recombination of H3+ and D3+ ions with electrons in a low temperature plasma are described. The experiments were carried out in the afterglow plasma in helium with a small admixture of Ar and parent gas (H2 or D2). For both ions a linear increase of measured apparent binary recombination rate coefficients (αeff) with increasing helium density was observed: αeff = αBIN + KHe[He]. From the measured dependencies, we have obtained for both ions the binary (αBIN) and the ternary (KHe) rate coefficients and their temperature dependence. For the description of observed ternary recombination a mechanism with two subsequent rate determining steps is proposed. In the first step, in H3++ e- (or D3++ e-) collision, a rotationally excited long-lived Rydberg molecule H3* (or D 3*) is formed. In the following step H 3* (or D3*) collides with a He atom of the buffer gas and this collision prevents autoionization of H3* (or D3*). Lifetimes of the formed H3* (or D3*) and corresponding ternary recombination rate coefficients have been calculated. The theoretical and measured binary and ternary recombination rate coefficients obtained for H3+ and D3+ ions are in good agreement. © 2010 Taylor & Francis