Probe absorption spectroscopy as a tool to study the excited states in a cooperative system of two organic molecules

The applicability of the method for measuring the probe absorption and gain spectra in a system of quantum emitters excited by a resonant driving field for studying cooperative photoluminescence is considered. The gain and attenuation of a probe signal in the system of two quantum emitters with the dipole–dipole interaction have been calculated for the conditions of observing the cooperative photoluminescence of a pair of impurity molecules described in the literature and close to them. The resulting dependences demonstrate the structure of excited collective molecular states, which can be used to reconstruct the positions of molecules in a matrix and to determine the difference in their photophysical properties. Thus, the probe absorption and gain spectra can be used to analyze the photoluminescence of quantum-entangled particles and to transform light signals.