Line-narrowing transient Raman technique which resolves closely spaced hydrogen-bonded aggregates

An ultrafast coherent Raman spectroscopy with tunable excitation is
presented. It is applied to the analysis of vibrational spectra of
hydrogen-bonded aggregates of pyridine and methanol. Whereas the
spontaneous Raman spectrum exhibits a broad and featureless band,
the line-narrowed spectra reveal three distinct lines. The
concentration dependence of these lines suggests an assignment to
well-defined aggregates of different sizes.