Research Group
Prof. Hühnerfuss
 

Characterization of anthropogenic and biogenic monolayers at the air/water interface

Monolayers at the air/water interface can be regarded as model systems for biomembranes and for sea surface films (so-called „slicks") which may accumulate at the air/ocean interface and thus interfer with various air/sea interaction processes. All processes, be it enzymatic processes at membrane surfaces or be it air/sea exchange processes, are closely related to the chemical structure and the intermolecular interaction between the film-forming molecules as well as to the macroscopic arrangement of the film molecules („morphology") and their interaction with the adjacent water layer.

Having in mind the implications of monolayer structure summarised above we perform systematic laboratory investigations that allow a characterization of monolayers at the air/water interface including Langmuir-trough, surface viscosity, surface potential, and surface tension measurements as well as External Infrared Reflection-Absorption Spectroscopy (IRRAS) and Brewster Angle Microscopy (BAM). Thus we gain deepened insight both into intermolecular interactions between the film-forming molecules, between the film molecules and the adjacent water molecules (i.e., on a molecular scale) and into the macroscopic thermodynamic implications of the intermolecular interactions.

Presently, special emphasis is being placed upon the study of chiral film-forming substances. The interactions between such compounds exhibiting a single chiral centre are generally classified as follows: a preferential D:D or L:L interaction is denoted as „homochiral" behaviour, while preferential D:L interaction is called „heterochiral". Homochiral interactions are of particular interest, because they raise the possibility of phase separation into regions of the L- and the D-enantiomers (sometimes referred to as „chiral discrimination" or „symmetry breaking").

The results thus obtained supply a valuable input into the experiments performed in the wind-wave tank of the University of Hamburg and into the experiments performed on the open sea in connection with international remote sensing campaigns (e.g., JONSWAP; MARSEN; SAR 580; SAXON-FPN; SIR-C X-SAR).

Furthermore, the results shed light on problems related to „self-organisation and function" as well as to „recognition processes at organic membranes".