Temperature dependence of the electron attachment coefficient in iodine

The attachment coefficient for iodine in a (1% I2+99% N2) mixture, 50 Torr total pressure, has been measured in an electron swarm experiment from 1 to 50 Townsends (1 Townsend=1Td=10−17 V cm2). As the temperature was increased from 35 to 110 °C, the attachment coefficient increased for any E/N (electric field intensity/gas number density) values greater than 7 Td. These results are compared to other experimental data and an explanation for the temperature dependence, based on the population of upper vibrational states, is presented.