Current Pulses in β-Carotene

Abstract

WE are at present investigating the absorption spectra and photoconduction behaviour, as well as the electric properties of polyene molecules, in particular, of the molecule β-carotene. This molecule occurs widely in plants and animals. Although β-carotene itself does not occur in the visual pigments it can be considered a precursor of retinene, the C₂₀ carotenoid, which occurs in the rods and cones of the retina. An attractive feature of this molecule to us was the possibility of growing single crystals and making our electrical and spectroscopic measurements along the different crystal directions. We have been able to make extremely thin crystals (∼ 500 Å thick), as well as much larger crystals, and we shall be reporting a full account of the work elsewhere¹. Here we wish to point out an interesting phenomenon observed during the electrical measurements.