Drift Velocities of Slow Electrons in Methane, Ethane, Ethylene, Propylene, Acetylene, and 1-Butene

A double-shutter drift tube was used to measure the drift velocities of electrons in methane, ethane, ethylene, acetylene, propylene, and 1-butene for low E/P values. The data were analyzed to obtain values of the momentum transfer cross section as a function of electron energy in the interval 0.010 to 0.063 eV. Cross sections were obtained by fitting a power series in electron velocity to the slope of electron-drift-velocity data in the thermal equilibrium range where electron velocities can be represented by a Maxwellian distribution.