Eur. Phys. J. D 35, 307-312 (2005)
https://doi.org/10.1140/epjd/e2005-00087-7

Measurements of thermal electron attachment rate coefficients to molecules using an electron swarm technique

¹ School of Physics and Astronomy, University of Birmingham, Edgbaston B15 2TT, UK
² Walsall College of Arts and Technology, St. Pauls Street, Walsall WS1 1XN, UK

Corresponding author: ^a c.mayhew@bham.ac.uk

Received: 7 March 2005
Published online: 14 June 2005

Abstract

An existing electron swarm apparatus has been redesigned and upgraded. In particular, the new design incorporates a novel planar radioactive foil to form an integral part of the drift tube, allowing us to overcome inherent problems present in our earlier system which used a cylindrical radioactive source. In addition to this, substantial upgrades have been made to improve the gating and amplification electronics and the data acquisition system. This has resulted in a much greater signal to noise ratio and improved accuracy. This paper describes the upgraded apparatus and its use in obtaining thermal (300 K) attachment rate coefficients to a number of molecules. The quality of the measurements and data are illustrated through the measurement of the thermal attachment rate coefficient for SF₆ (k_th(SF cm³ s. Thermal electron attachment rate coefficients for four other molecules are presented, namely for two derivatives of SF₆, SF₅CF₃ and SF₅Cl, and two perfluorocarbons, c-C₄F₈ and 2-C₄F₈.