X₁. Zwischenmolekularer Übergang von Elektronenanregungsenergie

The studies of sensitized fluorescence in gases and liquids arc discussed, and the possibility of detecting an nontrivial transfer of electronic energy considered. The elementary process of excitation transfer between molecules in thermal equilibrium with their environment is quantitatively treated for pure dipole‐dipole coupling and discussed qualitatively for other cases. The theorie of the elementary process is applied to solutions with statistical distributions of molecules. The transfer between like molecules can occur in several steps. Recent research at very low temperatures can be taken as evidence that such processes are important for the fluorescence of foreign molecules in molecular cristals.