Optically induced angular motion of single-molecules

Optically induced angular motion of individual molecules exhibiting both fluorescence and photo-isomerization properties is investigated in polymer films, by means of a polarized resonant optical pump and probe scheme. The single-molecule dynamics is analyzed using a kinetic model accounting for both photo-isomerization and thermal diffusion phenomena. This study shows that the process is strongly diffusion driven and reveals the relevant time scales that can lead to a pure light-induced molecular-rotation control.