Photophysical Parameters, Excitation Energy Transfer, and Photoreactivity of 1,4-Bis(5-phenyl-2-oxazolyl)‎benzene (POPOP)‎ Laser Dye

Abstract EN

The effect of solvents on the absorption and emission spectra of 1,4-bis(5-phenyl-2-oxazolyl)benzene (POPOP) laser dye has been studied in various solvents at 298 K.

A bathochromic shift was observed in absorption and fluorescence spectra upon increase of solvent polarity, which indicates that this transition is π-π*.

The ground and excited state dipole moments were calculated as 2.23 and 6.34 Debye, respectively.

The dye solution in MeOH, n-heptane, and methyl isobutyl ketone gives laser emission in the blue region upon excitation by a 337.1 nm nitrogen pulse; the gain coefficient and emission cross section as well as normalized photostability have been determined.

Excitation energy transfer from POPOP to rhodamine B and fluorescine was studied to improve the laser emission from these dyes.

Such an energy transfer dye laser system (ETDL) obeys a long range columbic energy transfer mechanism with a critical transfer distance, R0, of 25 and 33 Å and kq equal to 10.4×1012 and 26.2×1012 M−1 s −1 for the POPOP/RB and POPOP/fluorescine pair, respectively.

The POPOP dye is highly photostable in polar protic and polar aprotic solvents, while it displays photodecomposition in chloromethane solvent via formation of a contact ion pair.

The photochemical quantum yield and rate of photodecomposition depend on the electron affinity of solvent.