Schematic illustration of dynamic discrimination for two molecules with identical static absorption spectra. Similar but slightly different potential energy surfaces (which display energy versus two vibrational coordinates in the molecule) are shown for the two molecules FMN and RBF. A shaped UV pump pulse launches a tailored wave function on the potential energy surface of each molecule (large blue arrow). The wave functions evolve on the excited state surface (dotted white line) and are shaped (via the shaped UV laser pulse) to maximize the differences between them when the probe pulse arrives. The unshaped infrared probe pulse (small red arrow) transfers a portion of the wave function for one molecule (FMN in this case) to a final state from which fluorescence is not detected (small red arrow). The wave function in the other molecule (RBF) is in a different location when the probe pulse arrives, and it is therefore not transferred to the final state, leading to a larger fluorescence signal. A different shaped UV pulse can reverse the situation, leading to suppression of RBF fluorescence relative to FMN.