In this project in Experimental Physical Chemistry, Chemistry Division, Felker will use rotational coherence spectroscopy to obtain geometric structures of large species in supersonic molecular beams. This includes studies of aromatic-aromatic dimers and higher clusters, and investigations of how hydrogen-bonded networks evolve with cluster size. %%% By exposing molecules in the gas phase to short, sharp pulses of laser light at the proper frequency, Prof. Felker (UCLA) will obtain information about geometric structures of a small, controlled number of interacting molecules. This information is very useful for understanding how molecules behave in the initial stages of a wide variety of chemical reactions.