Fourier transform high-resolution spectroscopic studies of Gd I: optical isotope shifts in the spectral region of 18 700–20 200 cm−1

Abstract

Isotope shift (IS) measurements in 67 spectral lines were carried out for the neutral gadolinium atom in the wavelength region of 4950–5350 Å using a BOMEM DA8 Fourier transform spectrometer with a liquid-nitrogen-cooled hollow cathode lamp as a source and a photomultiplier tube as the detector. The present investigation provided experimental IS data in 44 lines for the first time. Out of 53 high even levels encountered in the studies, level ISs have become available for 13 for the first time. The study also contributed to confirmations of previously assigned 4f75d6s6p, 4f75d26p and 4f85d6s configurations for some of the even-parity energy levels. Strong configuration interaction has been observed in the few high even-parity levels pertaining to 4f75d6s6p and 4f75d26p configurations.