From Langmuir-Blodgett films to single molecules

The author recollects his time in the group of D. Möbius in 1985-1986, within the department headed by Hans Kuhn, and the influence of Kuhn's concept of molecular assembly in the gestation of the first single-molecule experiments. He then briefly surveys the recent applications of single-molecule spectroscopy to complex and heterogeneous systems. In particular the field of single-molecule microscopy in membranes and at biological interfaces is now strongly growing, closing the circle back to Langmuir films, the systems which led to the development of single-molecule optical techniques.