Nonequilibrium response spectroscopy is a novel method of analyzing the molecular kinetics of voltage-sensitive proteins that involves measuring of the nonequilibrium response of the molecules to fluctuating fields with large amplitudes and frequencies. This response is exquisitely sensitive to features of the kinetics that are difficult or impossible to resolve by means of more traditional relaxation transient experiments.

• Received 23 June 1997

DOI:https://doi.org/10.1103/PhysRevLett.80.401