Experimental Values of the Atomic Absorption Cross Section of Potassium Between 580 Å and 1000 Å*

The atomic absorption cross section of potassium has been measured between 580 and 1000 Å. The region between 685 and 1000 Å showed continuous absorption and the values around 1000 Å were consistent with those obtained previously. In the region between 580 and 685 Å several autoionization lines were observed, in particular two strong lines corresponding to the (3p)64s→(3p)5(4s)22P32,12 transitions. This spectral region was studied photoelectrically at a bandwidth of 0.37 Å and photographically at 0.075 Å. Curves and tables are presented of the atomic absorption cross sections of potassium versus energy from the series limit to 580 Å, and a comparison is made between these results and recent theoretical estimates. An attempt was made to fit Fano–Beutler profiles to the measured line shapes of the (3p)64s→(3p)5(4s)2-2P32,12 transitions and the resulting line-shape parameters are given. The sum of the oscillator strengths of these transitions was found to be 0.147.