Table 2. Energy and Lifetime of the Carotenoid S₁ (2¹A_g^–) State along with B850* Quenching Rate (if Evident).

carotenoid	Na	NC=C	NC=O	environment	S1 (cm–1) [nm]b	τS1c (ps) RTe	τS1c (ps) 77 K [10 K]	kq–1 (ns)d	ref
neurosporene	9	9	0	v.s.f	14 170–14 400 [695–706]				(44, 45)
						21–24			(44−47)
							34.8		(45)
				ΔcrtCg		1.2	1.2	n.e.h	this work
				G1Cg		1.2	[0.9]		(10)
				G1Cg		1.3			(48)
spheroidene	10	10	0	v.s.	13 400 [746]				(44, 49)
						7.7–9.3			(33, 48, 50, 51)
							11.5		(45)
				ΔcrtAg		1.4	1.6	n.e.	this work
				W.T.g		1.5	[1.5]		(10)
				W.T.		1.7			(48)
lycopene	11	11	0	v.s.	12 500 [800]				(33)
						4–4.7			(48, 52)
				ΔcrtI::crtIPaΔcrtCg		3.4	3.3	5.9	this work
				DPF240 [pERWI2]g		3.2			(33)
				Rps. molischianum		3.4			(48)
rhodopin	11	11	0	benzene	12 450 [803]	3.3			(53)
				ΔcrtI::crtIPaΔcrtDg		2.9	3.2	5.9	this work
spirilloxanthin	13	13	0	v.s.	11 350–11 500 [870–881]				(45, 53, 54)
						1.3–1.7			(41, 44, 45, 52−56)
							2.0		(45)
				ΔcrtI:crtIPa (PS)g	11 300 [885]	1.4	1.6		(24)
								2.6	this work
diketospirilloxanthin	15	13	2	v.s.	11 000–11 100 [900–909]	0.8	1.2		(24)
				ΔcrtI:crtIPa (SA)g	11 500 [870]	1.1	1.8		(24)
								1.6	this work

^aTotal number of conjugated double bonds (N = N_C=C + N_C=O).

^bEnergy value defined via measuring S₁ → S₂ energy gap.

^cCarotenoid S₁ (2¹A_g^–) state lifetime,

^dB850-to-carotenoid time constant (inverse rate constant) in LH2 assuming that unquenched B850 lifetime is 1.35 ns.

^eRoom temperature.

^fVarious solvents.

^gRb. sphaeroides strain.

^hNot evident.