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International Journal of Photoenergy
Volume 2012, Article ID 458126, 10 pages
Research Article

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

1Department of Chemistry, Faculty of Science, Tanta University, Tanta 31527, Egypt
2Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia
3Department of Physics, Faculty of Science, Tanta University, Tanta 31527, Egypt
4Faculty of Engineering, MUST, 6th of October City, Egypt
5Center of Excellence for Advanced Materials Research, King Abdul Aziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia

Received 20 February 2012; Accepted 6 April 2012

Academic Editor: Vincenzo Augugliaro

Copyright © 2012 Samy A. El-Daly et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


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 1 0 . 4 × 1 0 1 2 and 2 6 . 2 × 1 0 1 2 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.