. 2021 Dec 21;7(1):921–932. doi: 10.1021/acsomega.1c05386

Table 5. Luminescence Lifetimes for Ln³⁺ in Choline Chloride-Based DES. Nd³⁺: λ_Ex. = 355 nm, Monitor the ⁴F_3/2 → ⁴I_9/2 Emission. Eu³⁺: λ_Ex. = 416 nm, Monitor the ⁵D₀ → ⁷F₂ Transition. Dy³⁺: λ_Ex. = 435 nm, Monitor the ⁴F_9/2 → ⁶H_13/2 Transition.

	HBD	[Ln³⁺]/mol kg^–1	lifetime/μs	R²
Eu³⁺	ethylene glycol	0.020	71.6	0.9989
		0.015	103.5	0.9979
		0.010	137.9	0.9992
	urea	0.020	467.3	0.9992
		0.015	523.6	0.9989
		0.010	617.3	0.9992
	lactic acid	0.020	308.6	0.9997
		0.015	386.1	0.9997
		0.010	427.3	0.9995
Dy³⁺	ethylene glycol	0.020	7.2	0.9998
		0.015	7.3	0.9996
		0.010	7.3	0.9995
	urea	0.020	20.7	0.9995
		0.015	20.7	0.9996
		0.010	20.5	0.9993
Nd³⁺	ethylene glycol	0.020	79.8 × 10^–3	0.9992
		0.015	78.4 × 10^–3	0.9995
		0.010	77.5 × 10^–3	0.9993
	urea	0.020	197.6 × 10^–3	0.9999
		0.015	198.8 × 10^–3	0.9998
		0.010	202.4 × 10^–3	0.9998
	lactic acid	0.020	157.2 × 10^–3	0.9998
		0.015	156.0 × 10^–3	0.9997
		0.010	151.5 × 10^–3	0.9989

Table 5. Luminescence Lifetimes for Ln3+ in Choline Chloride-Based DES. Nd3+: λEx. = 355 nm, Monitor the 4F3/2 → 4I9/2 Emission. Eu3+: λEx. = 416 nm, Monitor the 5D0 → 7F2 Transition. Dy3+: λEx. = 435 nm, Monitor the 4F9/2 → 6H13/2 Transition.