Abstract
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 A 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.
Highlights
Fluorescent organic compounds possessing high Stokes shift values [1, 2] are prospective candidates for practical application in various fields of science and technology, where high concentrations or long optical paths are required [3, 4], for example, in scintillation techniques [5, 6], sunlight collection, and conversion of solar energy into electricity [7, 8], electroluminescent light sources (OLEDs) [9,10,11], and various biological applications, and so forth
In the present we report photophysical parameters, excitation energy transfer, and photoreactivity of POPOP laser dye (Scheme 1)
The emission spectra become red-shifted, Figure 2. This indicates that the singlet excited state of the POPOP molecule is more polar than the ground state
Summary
Fluorescent organic compounds possessing high Stokes shift values [1, 2] are prospective candidates for practical application in various fields of science and technology, where high concentrations or long optical paths are required [3, 4], for example, in scintillation techniques [5, 6], sunlight collection, and conversion of solar energy into electricity [7, 8], electroluminescent light sources (OLEDs) [9,10,11], and various biological applications, and so forth. Several physicochemical mechanisms can be applied to increase the fluorescence Stokes shift of organic compounds [12]; not all lead to emissions with high quantum yields [13]. Derivatives of 1,2-bis-(5-phenyloxazol-2-yl)benzene [23,24,25] are ortho analogs of the well-known scintillation luminophore POPOP [1,4-bis-(5-phenyloxazol-2-yl)benzene] They belong to the class of efficient fluorescent organic compounds with abnormally high Stokes shifts [26]. Further increase of the Stokes shift values is possible by combination of several photophysical mechanisms in one molecule: for example, excited state planarization and solvatochromic effects. In the present we report photophysical parameters, excitation energy transfer, and photoreactivity of POPOP laser dye (Scheme 1)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
