7 May 1997 Coumarin fluorescent probes by electro-optical and laser spectrofluorimetry methods
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Proceedings Volume 2980, Advances in Fluorescence Sensing Technology III; (1997) https://doi.org/10.1117/12.273543
Event: BiOS '97, Part of Photonics West, 1997, San Jose, CA, United States
Abstract
Modified electro-optical absorption and emission methods were used to measure the dipole moments of six coumarin fluorescent probes (CU1, CU4, CU7, CU30, CU120, CU334) in the equilibrated ground, excited Franck-Condon and equilibrated excited states. The measurements were performed in cyclohexane and dioxane at room temperature. The equilibrated ground and excited states dipole measured by electro-optical methods are compared with those derived from other measurements techniques and from semiempirical calculations. Experiments and calculations performed in this work reveal a set of anomalous and interesting properties of CU7 and CU30 in solutions. The spectral dependence of some electro-optical coefficients and, consequently, dipole moments in excited Franck-Condon state indicates that the absorption band is a superposition of several (at least two) electronic transitions. Most probably there are two close- lying singlet electronic states which contribute to the first absorption band. Our electro-optical and laser spectrofluorimetry measurements do not support the formation of twisted intramolecular charge transfer state after optical excitation in the studied coumarins, at least in cyclohexane and dioxane.
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Nicolai A. Nemkovich, Wolfram Baumann, Heribert Reis, Yurii V. Zvinevich, "Coumarin fluorescent probes by electro-optical and laser spectrofluorimetry methods", Proc. SPIE 2980, Advances in Fluorescence Sensing Technology III, (7 May 1997); doi: 10.1117/12.273543; https://doi.org/10.1117/12.273543
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