Absorption of Light by Potassium Vapor between 2856 and 1150 Å

The continuous atomic and molecular cross sections of potassium vapor have been measured using photoelectric techniques from the 4s²S→np²P⁰ series limit at 2856 to 1150 {}. The bandwidth of the monochromator was 0.75 {} and values of the cross sections were obtained at 2-{} intervals. The value obtained for the atomic absorption cross section at the series limit was 0.010±{}0.003 Mb or 0.012±{}0.003 Mb, depending on which vapor-pressure formula was used in the analysis of the results. A minimum of 0.002±{}0.002 Mb was observed between 2730 and 2600 {}. This latter result disagrees with previous experimental results but is in agreement with theoretical predictions.