Study of magnetic field effect on Py-DMA exciplex luminescence in THF–DMF binary solvents: Evidence of multiple exciplex formation at higher bulk dielectric constant

Magnetic field effects (MFE) on pyrene-DMA (N,N-dimethylaniline) exciplex system in THF–DMF binary solvents of varying bulk dielectric constant (ε) has been studied. The MFE has been wavelength resolved over the emission band of the exciplex. The data indicates formation of two types of exciplexes at higher bulk value of ε. At lower value of ε (ε < 9) essentially there is a single type of exciplex which is supported by the wavelength resolved MFE and life-time (τ) measurements. However, at higher value of ε (ε > 15) when the solvent reorganization energy is more prominent; the wavelength resolved MFE and life-time studies show evidence of two types of exciplexes.