Professor Nibler is supported by the Experimental Physical Chemistry Program in a continuing investigation of the properties of molecular clusters probed by nonlinear optical techniques. The work spans the size range from dimers to much larger clusters and addresses issues ranging from dimer structure and spectroscopic properties to the study of nucleation, growth, and surface and bulk properties of larger condensates. Large clusters of molecules, such as nitrogen, oxygen, hydrogen, carbon dioxide, and acetylene, are being probed by stimulated Raman scattering and coherent antistokes Raman scattering at various distances from the source nozzle of a free jet expansion. Both vibrational and pure rotational spectra are being produced, yielding information on the evolution of the cluster expansion and the condensation processes occuring. Work continues on Raman probing of dimers of nitrogen, oxygen, and hydrogen; these are important dimers whose centers of symmetry make them inaccessible spectroscopically except through use of Raman techniques.
