ESR line shape analysis for strongly distorted signals due to an intense paramagnetic sample: Application to spin polarized atomic hydrogen

We present a method suitable for a real time computer analysis of ESR signals strongly distorted due to an intense paramagnetic sample. This occurs typically in experiments with highQ cavities and narrow lines carried out at low temperatures. We have applied this method to ESR of gaseous spin polarized atomic hydrogen. During an experiment the density of gas atoms in a cavity may decrease a few orders of magnitude. Thus the ESR line shape evolves correspondingly from a regime of heavily distorted signals to that of undistorted ones. We have compared our analysis with independent measurements of the hydrogen density by a sensitive pressure gauge.