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Excimer

About: Excimer is a research topic. Over the lifetime, 3725 publications have been published within this topic receiving 75104 citations.


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Journal ArticleDOI
TL;DR: In this paper, it was shown that the emission spectrum of non-crystalline layers of anthracene, prepared by vacuum sublimation onto a 80 K substrate, consists of three distinct excimer bands.
Abstract: By employing time-resolved fluorescence spectroscopy it is shown that the emission spectrum of non-crystalline layers of anthracene, prepared by vacuum sublimation onto a 80 K substrate, consists of three distinct excimer bands. The band maxima are at 21 900 cm-1, 21 500 cm-1 and 19 600 cm-1, the corresponding lifetimes are 10 ns, 35 ns and 170 ns, respectively. The underlying molecular pair conformations, formed during sample preparation, must be metastable in the groundstate.

30 citations

Journal ArticleDOI
TL;DR: In this paper, four different pyrene-labeled polymers were prepared by radical copolymerization of n-butyl methacrylate (BMA) and 1-pyrenemethyl methacylate (PyEG0-MA), and the only structural difference between the polymers was the length of the oligo(ethylene glycol) spacer separating the pyrene label from the main chain.
Abstract: Four different pyrene-labeled polymers were prepared by radical copolymerization of n-butyl methacrylate (BMA) and 1-pyrenemethyl methacrylate (PyEG0-MA), 1-pyrenemethoxyethyl methacrylate (PyEG1-MA), 1-pyrenemethoxyethoxyethyl methacrylate (PyEG2-MA), and 1-pyrenemethoxydiethoxyethyl methacrylate (PyEG3-MA) to yield PyEG0–PBMA, PyEG1–PBMA, PyEG2–PBMA, and PyEG3–PBMA, respectively. The only structural difference between the polymers was the length of the oligo(ethylene glycol) spacer separating the pyrene label from the main chain. Steady-state and time-resolved fluorescence were applied to investigate how the length of the spacer affected the photophysical properties of the pyrene-labeled polymers. Excimer formation between an excited-state and a ground-state pyrene was enhanced by a longer spacer which increased the probability of encounter between two pyrene labels. This conclusion was supported through the analysis of the fluorescence decays of the polymers according to the fluorescence blob model (FB...

30 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used 2-(2′-hydroxyphenyl)-benzoxazole to suppress the laser action of dyes emitting in the transient absorption band.
Abstract: Molecules undergoing excited-state intramolecular proton transfer often show transient absorption after pulsed optical excitation, due to the tautomeric form in the singlet ground state. This absorption may be used to suppress, after a short time, the laser action of dyes emitting in the transient absorption band. The method is designed for high photochemical stability. Lasing from PBBO, pumped 10 times above threshold by an excimer pumped PTP dye laser, was suppressed after 3.3ns by the addition of 2-(2′-hydroxyphenyl)-benzoxazole, which absorbed 30% of the pump energy. At higher concentrations, intense and stable 80ps PBBO laser pulses were obtained. The pulse evolution is simulated by model calculations. A hypothetical super-dye, consisting of chemically linked laser- and absorber-moities, is also discussed. Here Forster energy transfer should result in particularly efficient laser pulse shortening.

30 citations

Journal ArticleDOI
TL;DR: In this paper, the optical and photophysical properties of fluorene-based polyesters in solution and in the solid state (thin films) were reported, and the red-shifted emission bands observed in the photoluminescence spectra of the thin films were rationalized in terms of stronger π−π intermolecular interactions due to the closeness of the molecules.
Abstract: The optical and photophysical properties of fluorene-based polyesters in solution and in the solid state (thin films) are reported. The red-shifted emission bands observed in the photoluminescence spectra of the thin films are rationalized in terms of stronger π−π intermolecular interactions due to the closeness of the molecules (molecular packing) in the solid state. This is further corroborated by time-resolved fluorescence decay measurements. However, these electronic interactions are not strong enough to induce excimer or aggregate formation. As such, the quenching excimer and/or aggregate deactivation channel found in many polymeric systems are less efficient in the present polyesters. As expected, the presence of ester linkages between adjacent oligomers causes an interruption of the electronic conjugation, thus limiting the fluorescence to the blue region. The fluorescence efficiencies of thin films, estimated from lifetime measurements of the polyesters in solution and in the solid state, are rela...

30 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023106
2022253
202142
202045
201959
201847