Spectroscopic and computational studies of 1,4-bis[β-(6-tertbutyl-2-benzoxazolyl)vinyl]benzene(BTBVB) laser dye

The electronic absorption, fluorescence spectra and photophysical parameters such as, molar absorptivity (ε), oscillator strength (f), transition dipole moment (μ12), and fluorescence quantum yield (φf) of BTBVB were determined in different solvents and micelles. Both electronic absorption and emission spectra are less sensitive to medium polarity which indicates little change in the dipole moment of singlet (S0) ground and excited state (S1) of BTBVB molecule upon excitation. The quantum yield for photochemical transformation (Фc) of BTBVB was calculated in different organic solvents such as DMSO, DMF, EtOH and CHCl3 at room temperature. The dye solutions in DMSO, DMF, CHCl3 and EtOH give laser emission in the blue-green region upon excitation by a 337.1 nm nitrogen pulse. The tuning range, gain coefficient (α) and emission cross-section (σe) have been determined. Excitation energy transfer from BTBVB to rhodamine B was studied in n-butanol, methanol and ethylene glycol to improve the laser emission from RB dye when excited by nitrogen laser. Such an energy transfer dye laser system (ETDL) obeys a long range columbic energy transfer mechanism with a critical transfer distance, R0, of 36 Å and kET equal 6×1012 M−1 s−1. The density functional theory (DFT) was used to optimize the ground and excited state geometry of the dye, the computed peaks of absorption and emission spectra are in a reasonable agreement with the experimental results.