Miroslaw Piotr Skrzypkowski

Measurement of the absolute yield of CO(a 3Π)+O products in the dissociative recombination of CO2+ ions with electrons

A flowing-afterglow technique is described for measuring the absolute yield of a radiative product state from ion–electron recombination. The technique is applied to CO2++e− dissociative recombination. The measured yield of CO(a 3Π)+O(3P) is 0.29±0.10. This includes cascade from higher triplet states of CO. The vibrational distribution in CO(a 3Π,v=0–3) is approximately Boltzmann, with an effective temperature of 4200±300 K. The measured rate constant for quenching of CO(a) by CO2 is (1.0±0.2)×10−11 cm3 s−1, somewhat lower than previous measurements.

ELECTRON-TEMPERATURE DEPENDENCE OF THE RECOMBINATION OF NH4+(NH3)N IONS WITH ELECTRONS

Abstract The two-body recombination of NH4+(NH3)2,3 cluster-ions with electrons has been studied in an afterglow experiment in which the electron temperature Te was elevated by radio-frequency heating from 300 K up to 900 K. The recombination coefficients for the n = 2 and n =3 cluster ions were found to be equal, α2(2) = α3(2) = (4.8 ± 0.5) × 10−6 cm3/s, and to vary with electron temperature as Te−0.65 rather than to be nearly temperature-independent as had been inferred from measurements in microwave-heated plasmas.

Optical Spectroscopy of Recombining Ions in Flowing Afterglow Plasmas

Spectroscopy has been an important tool in studies of dissociative recombination (DR) for many years. The early work by Biondi1 and coworkers established the dissociative nature of the process by demonstrating the Doppler broadening of spectral lines due to the momentum that is imparted to the separating recombination fragments. In more recent work, spectroscopic methods have been used to identify products of DR of diatomic and polyatomic ions and to quantitatively measure yields for specified states of radiating recombination products. The formation of products in radiating states is of potential interest for the interpretation of planetary spectra and perhaps those observed from interstellar clouds, and of course, experimenters hope that identification of product states will lead to new insights into the mechanisms of recombination.