Experimental Studies on Electronic Configuration Mixing for the Even-Parity Levels of Gd I Using Isotope Shifts Recorded in the Visible Region with FTS

B K Ankush,M N Deo

doi:10.1155/2013/741020

Abstract

Electronic configuration (4f6s6p + 4f5d6s6p + 4f5d6p) mixing studies in the high even-parity energy levels of Gd I spectrum have been carried out on the basis of isotope shift (IS) Δσ156,160 data recorded in 49 spectral lines partially in the visible wavelength region on Fourier Transform Spectrometer (FTS) and the relevant spectral line IS data available in the literature. We employed “Sharing rule” to the experimentally observed level isotope shifts (LIS) of the even-parity levels for finding the percentage composition of each configuration being mixed. An FTS spectrum of Gd I in the region of 365–495 nm acquired employing the highly enriched Gd isotopes in liquid nitrogen cooled hollow cathode lamp (HCL) as a light source and photomultiplier tube as the detector. The studies of altogether 48 even-levels have revealed that amongst the 20 high even parity levels assigned previously to>95%4f5d6s6p configuration, 10 levels have agreed verywell whereas 7 have exhibited large contribution of 4f5d6s6p configuration compared to 4f5d6p configuration and 3 levels have equal contribution of 4f5d6s6p and 4f5d6p configurations. Out of 8 unassigned levels, 6 have dominant 4f5d6s6p configuration compared to 4f5d6p configuration and the remaining two have dominancy in 4f5d6p configuration.

Highlights

Gadolinium occupies position in the middle of the lanthanide series and has the [Xe] 4f75d6s2ground state configuration generating highly complex first spectrum of neutral gadolinium atom (Gd I) [1]
Detailed electronic configuration interaction of the type (4f76s26p + 4f75d6s6p + 4f75d26p) configurations in 24 high even-parity levels has been established by Kronfeldt et al [26] employing theoretical and experimental hfs spectrum generated by laser induced resonance fluorescence spectroscopy
Energy level classification previously reported by us for the line at 418.2760 nm has been revised on the basis of data published in [3]

Summary

Introduction

Gadolinium occupies position in the middle of the lanthanide series and has the [Xe] 4f75d6s2ground state configuration generating highly complex first spectrum of neutral gadolinium atom (Gd I) [1]. Detailed electronic configuration interaction of the type (4f76s26p + 4f75d6s6p + 4f75d26p) configurations in 24 high even-parity levels has been established by Kronfeldt et al [26] employing theoretical and experimental hfs spectrum generated by laser induced resonance fluorescence spectroscopy. An identification of odd-parity energy level at 38024.792 cm−1 of 4f75d6s8s configuration was made by Nortershauser et al [27] in addition to the experimental IS and hfs splitting produced by double resonance-enhanced two-photon transition mass spectroscopic technique. A high-resolution diode-laser spectroscopy of some rare earths including a 682.83 nm transition of Gd I has been performed by Wakui et al [32] to derive the field shifts and 6s-electron densities. Jin et al [34] have studied IS and hfs in 5 transitions of Gd I using high-resolution atomic-beam UV laser spectroscopy technique. The present experimental studies have been taken up to investigate the detailed configuration mixings in the high even-parity levels of Gd I

Experimental

Results and Discussion

Literature data

Configuration Interaction Analysis of the High Even-Parity

Conclusion