Direct evidence for the sensitized formation of a metastable state of β-carotene

Abstract

β-Carotene solutions in deoxygenated hexane do not exhibit detectable transient changes in their absorption spectra, when flash-illuminated in apparatus having a resolution time of about 10^–5 sec. However, solutions containing in addition to β-carotene, substances such as anthracene, tetracene, benzanthracene or chlorophyll a, show a transient absorption with a maximum at 514 mµ, when so illuminated. The transient appears only when the actinic light is absorbed, partially or entirely, by the donor (i.e., anthracene, etc.); but not when it is absorbed only by the carotene.