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

Table 5

Even-parity energy levels (cm⁻¹) belonging to 4f⁸5d6s configuration are listed separately in Table 5. Configurations, terms, and 𝐽 values have been taken from [1]. LIS Δ𝑇^156,160 (cm⁻¹) values have been referred from [6–9].

Configuration	Term	Energy level (cm^−1)	𝐽	LIS, Δ𝑇^156,160 (cm^−1)	Suggested configuration
4f^85d6s	^9G	24854.297^c	6	0.037	4f^85d6s
		25380.885^b,c	5	0.043	4f^85d6s
		25820.720^a,b	4	0.038	4f^85d6s
(4f^85d6s)	^9F	27040.865^d	4	0.055	4f^85d6s
(4f^85d6s)	^9F	27041.751^a	3	0.063	4f^85d6s
—	^9F	27129.239	1	0.058	4f^85d6s
4f^85d6s?	^7F?	28414.925^a	5	0.037	4f^85d6s
4f^85d6s?	^7D?	31327.520^c	3	0.048	4f^85d6s

^aThis level has been encountered in [6]. ^bThis level has been encountered in [7]. ^cThis level has been encountered in [8]. ^dThis level has been encountered in [9]. Configuration stated in parenthesis of a level is the configuration assignment made in this laboratory and reported in [6].