Infrared Spectrum and Revised Energy Levels for Neutral Krypton
Craig J. Sansonetti, Marion Greene
We observed the spectrum of neutral krypton (Kr I) in its naturally occurring isotopic mixture as emitted by a microwave-excited electrodeless discharge lamp with the National Institute of Standards and Technology 2-m Fourier transform spectrometer. The spectra cover the region from 6699 to 12 200 with a resolution of 0.01 cm-1 and the region from 9000 to 47 782 with a resolution of 0.007 cm-1. We present a line list that includes more than 630 classified lines, about 290 newly observed, and provides an accurate and comprehensive description of the infrared spectrum. The response of the Fourier transform spectrometer was characterized by using a radiometrically calibrated tungsten strip lamp to obtain relative intensities accurate to 10 % or better over the entire spectral range for lines with good signal-to-noise ratio. All eight levels of the 4s24p5(2P3/2)6g configuration have been located as well as one previously unknown level of the 4s24p5(2P3/2)6f configuration. Our new data have been combined with previous precise measurements to determine improved values for 64 even and 77 odd parity levels of Kr I.