Experimental Estimate of the Oscillator Strength of the P2_32,12←S2_12 Transition of the Hydrogen Atom

The oscillator strength of the Lyman-α transition in the hydrogen atom has been determined by the line-absorption method. Hydrogen atoms were produced in a fast-flow system by a microwave discharge in a H2–He mixture. The hydrogen atoms absorbed the Lyman-α radiation at 1216 Å emitted by a hydrogen-neon lamp, and absolute atom concentration was determined by titration with NO2. On the basis of the photometric calibration curve determined in this way, oscillator strengths were calculated as a function of assumed emission-line profiles. The best fit to the experimental data yielded an oscillator strength of 1.09±0.27.