Three tunable lasers are used to generate a fully resonant nonparametric process that generates new coherent output at a higher energy than fluorescence interference in condensed phase molecular systems. The pentacene:phyphen;terphenyl system is used as a model to test the basic ideas of the method and to compare the results with comparable spectra obtained with a parametric process. The resonance enhancement is shown to reflect intermode coupling between different vibrational and vibronic modes. Interference is observed between transitions of different pentacene sites that reflects the differences in the parametric and nonparametric processes. These differences become the dominant characteristic determining the potential for fourhyphen;wave nonlinear mixing methods to provide resolution within inhomogeneously broadened electronic bands.
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