Relative Orbital and Magnetic Substate Amplitudes in Single-Foil Excitation of Fast Hydrogen Atoms

Within the limits set by our experimental apparatus, large-amplitude zero-field oscillations of H fine-structure amplitudes treated in a recent letter of Macek were not observed in polarization---versus---flight-path measurements on H_β, H_γ, and Ly_α emissions from suddenly excited H atoms (50- and 150-keV incident protons). Random initial phases for orbital and magnetic substates and approximately equal magnetic substate populations are indicated, in contrast to binary electron capture in gases. A successful test of the theoretical polarization of $2s$ Stark quench radiation was also made.