Calibration of oscillator-strength measurements for the principal-series transitions of potassium

Abstract

Oscillator-strength measurements have been calibrated against the radiative lifetime for the $4s-4p$ transition of potassium. This yields a value of (8.1±0.5)×${10}^{-21\mathrm{}}$ ${\mathrm{cm}}^2$ for the photoionization cross section at the series limit, and implies a value for the cross-section minimum in good quantitative agreement with that calculated by Seaton.