A definition of photoexcitation free energy of solvated molecules, Delta A(exc), is proposed by exploiting an analogy between optical transitions driven by the electromagnetic radiation and steered transformations in classical systems. We postulate the applicability of a 'spectroscopic version' of the Jarzynski equality (which was originally derived in the classical context) with a likely work distribution function obtainable from the experimental UV-vis spectrum, so to yield Delta A(exc) on empirical basis. Motivations that support such a postulate are provided, and tests of internal consistency are made on some model cases. (C) 2012 Elsevier B. V. All rights reserved.