Measurement and analysis of the spectrum of neutral arsenic

The atomic-emission spectrum of neutral arsenic has been remeasured from 1644 A to 1.2 μm and extended to 3.6 μm. The light source was a microwave-excited electrodeless discharge tube. Instrumentation used included two Fourier spectrometers and a number of concave grating spectrographs. The number of emission lines was increased from the published 333 lines to 1478, 1295 of which are classified as transitions between 95 odd-parity levels and 96 even-parity levels. Of these 191 levels, 104 were the result of this experimental endeavor. Of the previously known 87, 13 were newly classified and 15 reclassified as a result of our analysis. At present, 175 of the 191 levels are classified. The classifications of these levels were accomplished with the help of ab initio calculations and least-squares fitting methods. Designations are given in both LS and JK representation when possible along with calculated compositions in both representations of the levels consisting of less than 75% of a dominant eigenvector component