Fluorescence and fluorescence excitation spectra of 77 K glasses and room temperature solutions of a series of compounds homologous to trans-β-carotene with 5 (mini-5), 7 (mini-7), 9 (mini-9) and 11 (β-carotene) conjugated double bonds were measured. Dual emission of mini-5, 7 and 9 were observed at 77 K. For mini-5 and 7 the emission was largely dominated by a Stokes-shifted 2 1A - g(S 1) → 1 1A - g(S 0) emission, while the 1 1B + u(S 2) → 1 1A - g emission was dominating in mini-9 and β-carotene. From the 77 K absorption and fluorescence spectra of mini-5, 7 and 9 the 0-0 excitation energies of S 0 → S 2 ( E(S 2)) and S 0 → S 1 ( E(S 1)) transitions were estimated. From the shortest to the longest carotene E(S 2 was 29 400±500, 24 900±200 and 21 900±100 cm -, respectively, and for E(S 1) it was 22 700±1000, 19 900±1000 and 16 600±1000 cm -1. E(S 1) of β-carotene is extrapolated from the energies of the min-carotenes to be located at 14 500±1000 cm -1, which is significantly lower than the value found earlier by Raman spectroscopy (17 230±100 cm -1). The trend for linear (un)substituted polyenes, that the energy gap (Δ E) between S 2 and S 1 increases with the length of conjugation, was not observed for the mini-carotenes. For mini-5 Δ E is about 2000 cm -1 larger than for the unsubstituted polyene decapentaene, while Δ E for mini-7 agrees well with (un)substituted heptaene. In n-hexane at room temperature the fluorescence quantum yields of the S 1 → S 0 emission (φ 1) for mini-5 and 7 were to be (7±3)×10 -3 and (8±4)×10 -4, respectively, and the S 2 → S 0 emission (φ 2) for mini-9 and β-carotene they were (1.0±0.5)×10 -4 and (2±1)×10 -4, respectively. The estimated yield ratio (φ 1/φ 2) of the compounds decreased from ∾ 7000 for mini-5 to ∾ 0.1 for mini-9. For mini-9 in n-hexane, no emission from the S 1 state was observed while the emission showed up in carbon disulfide, which is explained by the smaller Δ E of mini-9 in carbon disuifide. The fluorescence lifetime of 2 1A - g of mini-5 in n-hexane at room temperature was found, by single-photon counting technique, to be (2.0±0.2) ns.