Figure 3: Emission spectra of pyrene ([Py]=10-4 M) in benzene (a) and ACN (b) and that of DMA ([DMA]=6 × 10-2 M) in benzene (c) and ACN (d). Intensities of the vibration peaks of pyrene show the well known dependence on the local permittivity. DMA emission is far weak than that of pyrene and it is structureless. The spike in (c) is due to the room temperature phosphoresence from solvent benzene itself.