Dynamics of the refractive index in Langmuir monolayers

We present theoretical description of dynamics of the refractive index in Langmuir monolayers subjected to continuous-wave (CW) laser radiation, using the mechanism of the local temperature fluctuations. Such mechanism can be applied to all monolayer systems that consist of rodlike molecules. The CW laser radiation induces conformational transitions of molecules in monolayer, which, after some time being in the excited state, come back into the ground state, thus renewing their initial shape and releasing energy into the medium, locally heating it. This leads to the local temperature change, which promotes new conformational transitions of molecules. Such nonlinear energy redistribution mechanism permits the conformational transition boundary to move. The existence of the transitions is seen from the change of the refractive index.