Doppler Effects in Hydrogen Canal Rays of Uniform Energies

Positive ions were produced by bombarding hydrogen with low-voltage electrons from a hot cathode. The ions formed passed beside the cathode into a strong field where they were accelerated by potentials up to 15 ,ooo volts. The ions then passed into an observation chamber, where the light emitted by the accelerated particles was photographed with a large three-prism spectrograph. With the usual canal-ray tubes broad displacements are obtained as Doppler effects due to the velocity distributions in the ions, maxima are sometimes present suggesting ions of various masses, and the ob- served displacement is always considerably less than that calculated from the potential difference on the tube. With the present tube sharp displaced lines of the Balmer series are obtained indicating homogeneous velocities, the displacements agree with those calculated from the potential for atomic ions, molecular ions, and triatomic molecular ions. These ions break up in the observation chamber giving hydrogen atoms which emit the Balmer series lines with Doppler effects corresponding to the velocities of the ions. At low pressures the displaced line due to the molecule ion becomes the strongest as suggested by previous experiments on the positive-ray analysis of ionization products