Studies of the photophysics of highly fluorescent Red Mega 480 laser dye in solutions: Steady state spectroscopy

• Solvent effect on absorption and fluorescence spectra of highly fluorescent Red Mega 480 laser dye studied.
• Bathochromic shift is observed with increasing polarity.
• Excited state dipole moments are larger than the ground state due to high polarity in excited state.
• Dipole moments are calculated by various methods.
• Linear solvation energy relationships are studied on the dye in reference to degree of solvation strength.

The absorption and fluorescence spectra of highly fluorescent industrially useful medium sized Red Mega 480 dye have been studied in various solvents at 298 K. The solute photophysical behavior depends strongly on the solute–solvent interactions. In order to understand the effect of inter molecular interactions on spectral behaviors of the dye in different solvents extent of this behavior can be analyzed by linear solvation energy relationships. In addition, ground and excited state dipole moments were evaluated by various methods. It is observed that excited state dipole moment (μe) is larger than the ground state (μg), absorption spectra show a bathochromic shift with increasing polarity indicating that transition involved is π → π∗ and Onsager cavity radius is determined by atomic increment method.

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