Measurements of the Total Cross Section for the Scattering of Low-Energy Electrons by Metastable Argon

Measurements are presented of the total cross section for scattering of low-energy electrons by a mixture of ${}_{}{}^3{}_{}{}^{}P_0^{}{}_{}{}^{}$ and ${}_{}{}^3{}_{}{}^{}P_2^{}{}_{}{}^{}$ metastable argon. The atom-beam-recoil method was used to make an absolute measurement. The cross section was measured from 0.35 to 6.75 eV with an angular resolution of 16.1° in the electron polar scattering angle at an electron energy of 1 eV. The velocity distribution of the atom beam was measured by time-of-flight spectroscopy. Electron beams with typical energy distributions of 0.3-eV full width at half-maximum were used. The over-all error in the cross section is estimated at ± 13% and the electron-energy determination is believed accurate to ± 0.150 eV.