Effect of optical saturation on hyperfine intensities in optogalvanic spectroscopy

Abstract

The hyperfine structure of the 22 125-cm−1, 2D°⅔ ← 2D⅔ lutetium transition has been examined by both Fourier-transform emission and laser optogalvanic spectroscopy. The component intensities of the Fourier-transform spectrum closely agree with classical intensities. The optogalvanic spectra show progressively larger deviations from classical intensities as the laser power is increased. Introduction of a single optical saturation parameter into the intensity formula is sufficient to fit the observed intensities even at high laser powers. These spectra were used to derive accurate values for the 176Lu line origin, the upper-state hyperfine constants of 175Lu, and the isotope shift between 176Lu and 175Lu.