The Experts below are selected from a list of 106722 Experts worldwide ranked by ideXlab platform
John D. Simon - One of the best experts on this subject based on the ideXlab platform.
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Primary Processes of the Electronic Excited States of trans-Urocanic Acid
Journal of Physical Chemistry A, 1997Co-Authors: Bulang Li, Kerry M. Hanson, John D. SimonAbstract:The primary photoreactivity of the excited states of trans-urocanic acid (t-UA) is investigated by ultrafast transient-absorption spectroscopy. Fundamentally different Photophysics were observed when t-UA is excited at 266 nm, near the peak of the absorption spectrum, and 306 nm, in the red tail of the absorption spectrum. The data support the conclusion that the wavelength-dependent Photophysics of t-UA is due to the presence of two different closely spaced electronic states. Excitation at 266 nm populates a ππ* state that is localized on the imidazole ring. The transient data following photoexcitation of t-UA at 266 nm in both a pH 5.6 and a pH 7.2 solution are similar, even though the protonation state of the tertiary nitrogen on the imidazole ring is different at these two pH values. The data therefore support that the Photophysics at pH 5.6 and pH 7.2 must involve a common excited state. Steady-state excitation spectra suggest that a proton transfer process from t-UA to the solvent occurs following t...
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Primary Processes of the Electronic Excited States of trans-Urocanic Acid
The Journal of Physical Chemistry A, 1997Co-Authors: Kerry M. Hanson, John D. SimonAbstract:The primary photoreactivity of the excited states of trans-urocanic acid (t-UA) is investigated by ultrafast transient-absorption spectroscopy. Fundamentally different Photophysics were observed wh...
Kerry M. Hanson - One of the best experts on this subject based on the ideXlab platform.
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Primary Processes of the Electronic Excited States of trans-Urocanic Acid
Journal of Physical Chemistry A, 1997Co-Authors: Bulang Li, Kerry M. Hanson, John D. SimonAbstract:The primary photoreactivity of the excited states of trans-urocanic acid (t-UA) is investigated by ultrafast transient-absorption spectroscopy. Fundamentally different Photophysics were observed when t-UA is excited at 266 nm, near the peak of the absorption spectrum, and 306 nm, in the red tail of the absorption spectrum. The data support the conclusion that the wavelength-dependent Photophysics of t-UA is due to the presence of two different closely spaced electronic states. Excitation at 266 nm populates a ππ* state that is localized on the imidazole ring. The transient data following photoexcitation of t-UA at 266 nm in both a pH 5.6 and a pH 7.2 solution are similar, even though the protonation state of the tertiary nitrogen on the imidazole ring is different at these two pH values. The data therefore support that the Photophysics at pH 5.6 and pH 7.2 must involve a common excited state. Steady-state excitation spectra suggest that a proton transfer process from t-UA to the solvent occurs following t...
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Primary Processes of the Electronic Excited States of trans-Urocanic Acid
The Journal of Physical Chemistry A, 1997Co-Authors: Kerry M. Hanson, John D. SimonAbstract:The primary photoreactivity of the excited states of trans-urocanic acid (t-UA) is investigated by ultrafast transient-absorption spectroscopy. Fundamentally different Photophysics were observed wh...
Peter R Ogilby - One of the best experts on this subject based on the ideXlab platform.
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temperature sensitive singlet oxygen photosensitization by lov derived fluorescent flavoproteins
Journal of Physical Chemistry B, 2017Co-Authors: Michael Westberg, Mikkel Bregnhoj, Michael Etzerodt, Peter R OgilbyAbstract:Optogenetic sensitizers that selectively produce a given reactive oxygen species (ROS) constitute a promising tool for studying cell signaling processes with high levels of spatiotemporal control. However, to harness the full potential of this tool for live cell studies, the Photophysics of currently available systems need to be explored further and optimized. Of particular interest in this regard, are the flavoproteins miniSOG and SOPP, both of which (1) contain the chromophore flavin mononucleotide, FMN, in a LOV-derived protein enclosure, and (2) photosensitize the production of singlet oxygen, O2(a1Δg). Here we present an extensive experimental study of the singlet and triplet state Photophysics of FMN in SOPP and miniSOG over a physiologically relevant temperature range. Although changes in temperature only affect the singlet excited state Photophysics slightly, the processes that influence the deactivation of the triplet excited state are more sensitive to temperature. Most notably, for both protein...
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temperature sensitive singlet oxygen photosensitization by lov derived fluorescent flavoproteins b
The Journal of Physical Chemistry, 2017Co-Authors: Michael Westberg, Mikkel Bregnhoj, Michael Etzerodt, Peter R OgilbyAbstract:Optogenetic sensitizers that selectively produce a given reactive oxygen species (ROS) constitute a promising tool for studying cell signaling processes with high levels of spatiotemporal control. However, to harness the full potential of this tool for live cell studies, the Photophysics of currently available systems need to be explored further and optimized. Of particular interest in this regard, are the flavoproteins miniSOG and SOPP, both of which (1) contain the chromophore flavin mononucleotide, FMN, in a LOV-derived protein enclosure, and (2) photosensitize the production of singlet oxygen, O₂(a¹Δg). Here we present an extensive experimental study of the singlet and triplet state Photophysics of FMN in SOPP and miniSOG over a physiologically relevant temperature range. Although changes in temperature only affect the singlet excited state Photophysics slightly, the processes that influence the deactivation of the triplet excited state are more sensitive to temperature. Most notably, for both proteins, the rate constant for quenching of ³FMN by ground state oxygen, O₂(X³Σg–), increases ∼10-fold upon increasing the temperature from 10 to 43 °C, while the oxygen-independent channels of triplet state deactivation are less affected. As a consequence, this increase in temperature results in higher yields of O₂(a¹Δg) formation for both SOPP and miniSOG. We also show that the quantum yields of O₂(a¹Δg) production by both miniSOG and SOPP are mainly limited by the fraction of FMN triplet states quenched by O₂(X³Σg–). The results presented herein provide a much-needed quantitative framework that will facilitate the future development of optogenetic ROS sensitizers.
Michael Westberg - One of the best experts on this subject based on the ideXlab platform.
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temperature sensitive singlet oxygen photosensitization by lov derived fluorescent flavoproteins
Journal of Physical Chemistry B, 2017Co-Authors: Michael Westberg, Mikkel Bregnhoj, Michael Etzerodt, Peter R OgilbyAbstract:Optogenetic sensitizers that selectively produce a given reactive oxygen species (ROS) constitute a promising tool for studying cell signaling processes with high levels of spatiotemporal control. However, to harness the full potential of this tool for live cell studies, the Photophysics of currently available systems need to be explored further and optimized. Of particular interest in this regard, are the flavoproteins miniSOG and SOPP, both of which (1) contain the chromophore flavin mononucleotide, FMN, in a LOV-derived protein enclosure, and (2) photosensitize the production of singlet oxygen, O2(a1Δg). Here we present an extensive experimental study of the singlet and triplet state Photophysics of FMN in SOPP and miniSOG over a physiologically relevant temperature range. Although changes in temperature only affect the singlet excited state Photophysics slightly, the processes that influence the deactivation of the triplet excited state are more sensitive to temperature. Most notably, for both protein...
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temperature sensitive singlet oxygen photosensitization by lov derived fluorescent flavoproteins b
The Journal of Physical Chemistry, 2017Co-Authors: Michael Westberg, Mikkel Bregnhoj, Michael Etzerodt, Peter R OgilbyAbstract:Optogenetic sensitizers that selectively produce a given reactive oxygen species (ROS) constitute a promising tool for studying cell signaling processes with high levels of spatiotemporal control. However, to harness the full potential of this tool for live cell studies, the Photophysics of currently available systems need to be explored further and optimized. Of particular interest in this regard, are the flavoproteins miniSOG and SOPP, both of which (1) contain the chromophore flavin mononucleotide, FMN, in a LOV-derived protein enclosure, and (2) photosensitize the production of singlet oxygen, O₂(a¹Δg). Here we present an extensive experimental study of the singlet and triplet state Photophysics of FMN in SOPP and miniSOG over a physiologically relevant temperature range. Although changes in temperature only affect the singlet excited state Photophysics slightly, the processes that influence the deactivation of the triplet excited state are more sensitive to temperature. Most notably, for both proteins, the rate constant for quenching of ³FMN by ground state oxygen, O₂(X³Σg–), increases ∼10-fold upon increasing the temperature from 10 to 43 °C, while the oxygen-independent channels of triplet state deactivation are less affected. As a consequence, this increase in temperature results in higher yields of O₂(a¹Δg) formation for both SOPP and miniSOG. We also show that the quantum yields of O₂(a¹Δg) production by both miniSOG and SOPP are mainly limited by the fraction of FMN triplet states quenched by O₂(X³Σg–). The results presented herein provide a much-needed quantitative framework that will facilitate the future development of optogenetic ROS sensitizers.
Xavier Allonas - One of the best experts on this subject based on the ideXlab platform.
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joint spectroscopic and theoretical investigation of cationic cyanine dye astrazon orange r solvent viscosity controlled relaxation of excited states
Physical Chemistry Chemical Physics, 2015Co-Authors: Patrice Bordat, Luciano H Di Stefano, Lola Remongin, Patrice Jacques, Ahmad Ibrahim, Xavier AllonasAbstract:In this paper, the first study of cationic cyanine dye Astrazon Orange-R by combined spectroscopic and theoretical investigation is presented. It is shown that molecular modeling of Astrazon Orange-R is in very good agreement with experiment, allowing us to gain insight into its complicated Photophysics. A solvent viscosity controlled relaxation of excited states, involving cyanine isomerization, is also outlined.
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Joint spectroscopic and theoretical investigation of cationic cyanine dye Astrazon Orange-R: Solvent viscosity controlled relaxation of excited states
Physical Chemistry Chemical Physics, 2015Co-Authors: C. Ley, Luciano H Di Stefano, Lola Remongin, Patrice Bordat, Ahmad Ibrahim, P. Jacquesa, Xavier AllonasAbstract:In this paper, the first study of cationic cyanine dye Astrazon Orange-R by combined spectroscopic and theoretical investigation is presented. It is shown that molecular modeling of Astrazon Orange-R is in very good agreement with experiment, allowing us to gain insight into its complicated Photophysics. A solvent viscosity controlled relaxation of excited states, involving cyanine isomerization, is also outlined. © the Owner Societies 2015.
