Table 1.

S₀ (1¹A_g⁻) → S₂ (1₁B_u⁺) and S₀ (1₁A_g⁻) → S₁(2₁A_g⁻) transition energies of various carotenoids. n, number of conjugated double bonds; THF, tetrahydrofuran; EPA, ether/isopentane/ethanol = 5/5/2(v/v/v); RT, room temperature.

		transition energy (cm−1)		condition
n	carotenoid	S0(11Ag−) → S2(11Bu+)	S0(11Ag−) → S1(21Ag−)	solvent, temperature (K)		references
13	all-trans-spirilloxanthin	18 900(100)		5% benzene/3-methyl pentane	295,150	[72,73]
		18 083		THF	RT	[74]
12	all-trans-anhydrorhodovibrin	19 400		n-hexane or 3-methyl pentane	295	[72]
		19 100(100)		n-hexane	295,150	[72,73]
11	all-trans-β-carotene	22 040		n-hexane	293	[60]
		21 390(100)		toluene, isopentane	293,77	[60]
		20 890(150)		quinoline	293	[60]
		20 300(100)	13 200(300)	n-hexane	170,RT	[63]
		19 700(100)	13 100(300)	toluene	RT	[63]
		19 580		isopentane	4.2	[60]
		19 380		carbon disulfide	RT	[61]
		19 150		n-hexane	77	[10]
		18 800(100)	13 200(300)	carbon disulfide	RT	[75]
		18 400	14 500	single crystal	11	[68]
	β-apo-4'-carotene	19 700(10)		EPA	77	[66]
	all-trans-lycopene	19 800(200)		n-hexane, acetone	170,RT	[73]
		18 600		n-hexane	77	[75]
			13 300	5% benzene/3-methyl pentane	RT	[76]
10	β-apo-6'-carotene	20 450(15)		EPA	77	[66]
	rhodopin	18 490		carbon disulfide	RT	[61]
	all-trans-spheroidene	20 800		methanol	RT	[64]
		20 250(150)	14 200	n-hexane	200	[65,72]
		19 600	14 200	film, n-hexane	77	[69]
		18 138		carbon disulfide	RT	[61]
			14 250(50)	n-hexane	77, RT	[75,76]
9	all-trans-neurosporene	21 100		n-hexane	190	[65]
		20 880(80)		n-hexane	190, RT	[65]
		19 800		n-hexane	RT	[61]
			15 300	n-hexane	RT	[76]
	β-apo-6'-carotenol	20 490		EPA	77	[62]
	isozeaxanthin	19 890		EPA	77	[62]