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 3

Odd-parity energy levels (cm⁻¹), their configurations, term, and 𝐽 values have been taken from [1]. LIS Δ𝑇^156,160 (cm⁻¹) have been referred from [6–9].

Configuration	Term	Energy level (cm^−1)	𝐽	LIS, Δ𝑇^156,160 (cm^−1)	Reference
4f^75d6s^2	^9D^0	0.000	2	0.176^$	[6–9]
		215.124	3	0.177^$	[6–9]
		532.977	4	0.178^$	[6–9]
		999.121	5	0.178^$	[6–9]
		1719.087	6	0.178	[6–9]
4f^75d^26s	^11F^0	6378.146	2	0.091^$	[8, 9]
		6550.395	3	0.089^$	[8, 9]
		6786.184	4	0.093^$	[8, 9]
		7103.420	5	0.095^$	[7, 8]
		7480.348	6	0.086	[8]
		7947.294	7	0.084	[7, 8]
		8498.434	8	0.085	[7, 8]
4f^75d6s^2	^7D^0	6976.508	5	0.177^$	[6, 7, 9]
		7234.910	4	0.178	[6–9]
		7426.710	3	0.179^$	[6–9]
		7562.457	2	0.179^$	[6–9]
4f^75d^26s	^9F^0	10883.505	4	0.076	[7–9]
		11830.393	6	0.073	[7–9]
		12486.547	7	0.074	[7–9]
4f^75d6s7s	^9D^0	39458.410	6	0.110
4f^86s6p		40894.570	5	0.114	[8]
4f^86s6p		41370.473	4	0.110	[8]

^$We have marginally revised the LIS Δ𝑇^156,160 (cm⁻¹) values of these levels on the basis of present IS data obtained using FTS combining with the data available in the literature mostly studied by laser spectroscopy.