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 Kuhnʹs 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.