Linewidths in the Electron Paramagnetic Resonance Spectrum of Gaseous Atomic Hydrogen

Abstract

A theory of the paramagnetic linewidth in gaseous atomic hydrogen, based on the theory of Baranger, and on an expansion of the spin correlation function in powers of the density is presented. To the approximations considered, the line shape is Lorentzian, the linewidth is proportional to the H atom density, and the relevant cross section involves an interference between the scattered amplitudes from the singlet and triplet potential curves. Comparison with experiment yields a velocity averaged cross section of 28.3×10—16 cm2 at 325°K. This value is compared to other estimates found in the literature.