The Experts below are selected from a list of 23985 Experts worldwide ranked by ideXlab platform
Takayoshi Kobayashi - One of the best experts on this subject based on the ideXlab platform.
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Development of Ultrashort Pulse Lasers for Ultrafast Spectroscopy
Photonics, 2018Co-Authors: Takayoshi KobayashiAbstract:Principles and information obtained by Ultrafast Spectroscopy and scheme of optical parametric amplifier are discussed. Realization of ultrashort visible and ultraviolet lasers based on the parametric processes are discussed.
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Development of Sub 10 fs Visible-NIR, UV, and DUV Pulses and Their Applications to Ultrafast Spectroscopy
Photonics, 2016Co-Authors: Takayoshi Kobayashi, Atsushi Yabushita, Yuichiro KidaAbstract:In the first section of this Chapter, the basics of nonlinear optical (NLO) processes are systematically described. Then the generation of the visible pulse utilizing the NLO processes is described and Ultrafast Spectroscopy using the visible pulse is discussed. By using such short pulse, fast chemical reactions, which cannot be identified by utilizing strobe light or flash lamp, can be studied. After the development of femtosecond lasers, they have been widely applied to observe the transition state of various chemical reactions. In the near infrared (NIR) region, a commercial light source of Ti:sapphire laser is available as a femtosecond light source, but not available in the visible and ultraviolet (UV) regions. In this article, we report our development of sub 10 fs visible-NIR, UV, and deep-ultraviolet (DUV) pulses and their applications to Ultrafast Spectroscopy.
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Ultrafast Spectroscopy of poly-thiophene derivative by using sub-10 fs visible pulse
Conference on Lasers and Electro-Optics 2012, 2012Co-Authors: Atsushi Yabushita, Yu Hsien Lee, Chain-shu Hsu, Sheng-hsiung Yang, Chih-wei Luo, Takayoshi KobayashiAbstract:Ultrafast Spectroscopy was performed for a poly(3-hexylthiophene) (P3HT) film changing pump power. The result clarified the femtosecond time constant for generation and relaxation of the bound polaron pair in the film.
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Ultrafast Spectroscopy of Oxyhemoglobin during Photodissociation
The journal of physical chemistry. B, 2010Co-Authors: Atsushi Yabushita, Takayoshi KobayashiAbstract:Ultrafast time-resolved pump−probe Spectroscopy was studied to clarify the detailed mechanism in the photodissociation process of oxyhemoglobin in the visible spectral range. The photodissociation had not been time-resolved and only the upper limit of the time needed for the dissociation process was claimed to be faster than 50 fs; it was time-resolved to be 45 ± 5 fs with 10 fs time resolution. The broadband spectrum of the visible laser pulses enabled us to observe the signal over a broad spectral range. A broadband multichannel detector array was used to simultaneously obtain the pump−probe signal at all probe frequencies. Thus, we obtained for the first time the spectra of the ultrashort lifetime electronic excited state of HbO2 in the visible range from 523 nm (19 109 cm−1) to 719 nm (13 914 cm−1). After the photodissociation, subpicosecond time constant was found and attributed to the dynamics of the photolyzed Hb. Time-resolved difference absorption spectra in 0−100 fs showed oscillatory motion ref...
Nadja Regner - One of the best experts on this subject based on the ideXlab platform.
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light switchable hemithioindigo hemistilbene containing peptides Ultrafast Spectroscopy of the z e isomerization of the chromophore and the structural dynamics of the peptide moiety
Journal of Physical Chemistry B, 2012Co-Authors: Nadja Regner, Teja T Herzog, Karin Haiser, Christian Hoppmann, Michael Beyermann, Jorg Sauermann, Martin Engelhard, Thorben Cordes, K RuckbraunAbstract:Two hemithioindigo–hemistilbene (HTI) derivatives, designed to operate as structural switches in peptides, as well as two HTI peptides are characterized by Ultrafast Spectroscopy in the visible and the infrared. The two HTI switches follow the reaction scheme published for other HTI compounds with a picosecond excited state reaction (τ1 ≈ 6 ps) and isomerization from Z to E with τ2 = 13 and 51 ps. As compared to the isolated chromophores, the isomerization reaction is slowed down in the chromopeptides to τ2 = 24 and 69 ps. For the smaller peptide containing 6 amino acids, the structural changes of the peptide moiety observed via the IR spectrum in the amide I band follow the isomerization of the molecular switch closely. In the larger cyclic chromopeptide, containing 20 amino acids and mimicking a β-hairpin structure in the Z-form of the chromophore, the peptide moiety also changes its structure during isomerization of the chromophore. However, the IR spectrum at the end of the observation period of 3 ns ...
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Light-switchable hemithioindigo-hemistilbene-containing peptides: Ultrafast Spectroscopy of the Z → E isomerization of the chromophore and the structural dynamics of the peptide moiety.
The journal of physical chemistry. B, 2012Co-Authors: Nadja Regner, Teja T Herzog, Karin Haiser, Christian Hoppmann, Michael Beyermann, Jorg Sauermann, Martin Engelhard, Thorben Cordes, Karola Rück-braun, Wolfgang ZinthAbstract:Two hemithioindigo–hemistilbene (HTI) derivatives, designed to operate as structural switches in peptides, as well as two HTI peptides are characterized by Ultrafast Spectroscopy in the visible and the infrared. The two HTI switches follow the reaction scheme published for other HTI compounds with a picosecond excited state reaction (τ1 ≈ 6 ps) and isomerization from Z to E with τ2 = 13 and 51 ps. As compared to the isolated chromophores, the isomerization reaction is slowed down in the chromopeptides to τ2 = 24 and 69 ps. For the smaller peptide containing 6 amino acids, the structural changes of the peptide moiety observed via the IR spectrum in the amide I band follow the isomerization of the molecular switch closely. In the larger cyclic chromopeptide, containing 20 amino acids and mimicking a β-hairpin structure in the Z-form of the chromophore, the peptide moiety also changes its structure during isomerization of the chromophore. However, the IR spectrum at the end of the observation period of 3 ns ...
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Light-Switchable Hemithioindigo–Hemistilbene-Containing Peptides: Ultrafast Spectroscopy of the Z → E Isomerization of the Chromophore and the Structural Dynamics of the Peptide Moiety B
The Journal of Physical Chemistry, 2012Co-Authors: Nadja Regner, Teja T Herzog, Karin Haiser, Christian Hoppmann, Michael Beyermann, Jorg Sauermann, Martin Engelhard, Thorben Cordes, K. Rück-braun, Wolfgang ZinthAbstract:Two hemithioindigo–hemistilbene (HTI) derivatives, designed to operate as structural switches in peptides, as well as two HTI peptides are characterized by Ultrafast Spectroscopy in the visible and the infrared. The two HTI switches follow the reaction scheme published for other HTI compounds with a picosecond excited state reaction (τ₁ ≈ 6 ps) and isomerization from Z to E with τ₂ = 13 and 51 ps. As compared to the isolated chromophores, the isomerization reaction is slowed down in the chromopeptides to τ₂ = 24 and 69 ps. For the smaller peptide containing 6 amino acids, the structural changes of the peptide moiety observed via the IR spectrum in the amide I band follow the isomerization of the molecular switch closely. In the larger cyclic chromopeptide, containing 20 amino acids and mimicking a β-hairpin structure in the Z-form of the chromophore, the peptide moiety also changes its structure during isomerization of the chromophore. However, the IR spectrum at the end of the observation period of 3 ns deviates significantly from the stationary difference spectrum. These signatures indicate that strong additional structural changes, e.g., breaking of interchain hydrogen bonds, also occur on longer time scales.
Wolfgang Zinth - One of the best experts on this subject based on the ideXlab platform.
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Light-switchable hemithioindigo-hemistilbene-containing peptides: Ultrafast Spectroscopy of the Z → E isomerization of the chromophore and the structural dynamics of the peptide moiety.
The journal of physical chemistry. B, 2012Co-Authors: Nadja Regner, Teja T Herzog, Karin Haiser, Christian Hoppmann, Michael Beyermann, Jorg Sauermann, Martin Engelhard, Thorben Cordes, Karola Rück-braun, Wolfgang ZinthAbstract:Two hemithioindigo–hemistilbene (HTI) derivatives, designed to operate as structural switches in peptides, as well as two HTI peptides are characterized by Ultrafast Spectroscopy in the visible and the infrared. The two HTI switches follow the reaction scheme published for other HTI compounds with a picosecond excited state reaction (τ1 ≈ 6 ps) and isomerization from Z to E with τ2 = 13 and 51 ps. As compared to the isolated chromophores, the isomerization reaction is slowed down in the chromopeptides to τ2 = 24 and 69 ps. For the smaller peptide containing 6 amino acids, the structural changes of the peptide moiety observed via the IR spectrum in the amide I band follow the isomerization of the molecular switch closely. In the larger cyclic chromopeptide, containing 20 amino acids and mimicking a β-hairpin structure in the Z-form of the chromophore, the peptide moiety also changes its structure during isomerization of the chromophore. However, the IR spectrum at the end of the observation period of 3 ns ...
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Light-Switchable Hemithioindigo–Hemistilbene-Containing Peptides: Ultrafast Spectroscopy of the Z → E Isomerization of the Chromophore and the Structural Dynamics of the Peptide Moiety B
The Journal of Physical Chemistry, 2012Co-Authors: Nadja Regner, Teja T Herzog, Karin Haiser, Christian Hoppmann, Michael Beyermann, Jorg Sauermann, Martin Engelhard, Thorben Cordes, K. Rück-braun, Wolfgang ZinthAbstract:Two hemithioindigo–hemistilbene (HTI) derivatives, designed to operate as structural switches in peptides, as well as two HTI peptides are characterized by Ultrafast Spectroscopy in the visible and the infrared. The two HTI switches follow the reaction scheme published for other HTI compounds with a picosecond excited state reaction (τ₁ ≈ 6 ps) and isomerization from Z to E with τ₂ = 13 and 51 ps. As compared to the isolated chromophores, the isomerization reaction is slowed down in the chromopeptides to τ₂ = 24 and 69 ps. For the smaller peptide containing 6 amino acids, the structural changes of the peptide moiety observed via the IR spectrum in the amide I band follow the isomerization of the molecular switch closely. In the larger cyclic chromopeptide, containing 20 amino acids and mimicking a β-hairpin structure in the Z-form of the chromophore, the peptide moiety also changes its structure during isomerization of the chromophore. However, the IR spectrum at the end of the observation period of 3 ns deviates significantly from the stationary difference spectrum. These signatures indicate that strong additional structural changes, e.g., breaking of interchain hydrogen bonds, also occur on longer time scales.
Eric Vauthey - One of the best experts on this subject based on the ideXlab platform.
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Bimolecular photoinduced electron transfer reactions in liquids under the gaze of Ultrafast Spectroscopy
Physical chemistry chemical physics : PCCP, 2014Co-Authors: Arnulf Rosspeintner, Eric VautheyAbstract:Because of their key role in many areas of science and technology, bimolecular photoinduced electron transfer reactions have been intensively studied over the past five decades. Despite this, several important questions, such as the absence of the Marcus inverted region or the structure of the primary reaction product, have only recently been solved while others still remain unanswered. Ultrafast Spectroscopy has proven to be extremely powerful to monitor the entire electron transfer process and to access, with the help of state-of-the-art theoretical models of diffusion-assisted reactions, crucial information like e.g. the intrinsic charge separation dynamics beyond the diffusion limit. Additionally, extension of these experimental techniques to other spectral regions than the UV-visible, such as the infrared, has given a totally new insight into the nature, the structure and the dynamics of the key reaction intermediates, like exciplexes and ions pairs. In this perspective, we highlight these recent progresses and discuss several aspects that still need to be addressed before a thorough understanding of these processes can be attained.
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Investigations of bimolecular photoinduced electron transfer reactions in polar solvents using Ultrafast Spectroscopy
Journal of Photochemistry and Photobiology A-chemistry, 2006Co-Authors: Eric VautheyAbstract:Several controversial questions in the field of bimolecular photoinduced electron transfer reactions in polar solvents are first briefly reviewed. Results obtained in our group using Ultrafast Spectroscopy and giving a new insight into these problems will then be described. They concern the driving force dependence of the charge separation distance, the formation of the reaction product in an electronic excited state, the absence of normal region for weakly exergonic charge recombination processes and the excitation wavelength dependence of the CR dynamics of donor–acceptor complexes.
Christian Hoppmann - One of the best experts on this subject based on the ideXlab platform.
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light switchable hemithioindigo hemistilbene containing peptides Ultrafast Spectroscopy of the z e isomerization of the chromophore and the structural dynamics of the peptide moiety
Journal of Physical Chemistry B, 2012Co-Authors: Nadja Regner, Teja T Herzog, Karin Haiser, Christian Hoppmann, Michael Beyermann, Jorg Sauermann, Martin Engelhard, Thorben Cordes, K RuckbraunAbstract:Two hemithioindigo–hemistilbene (HTI) derivatives, designed to operate as structural switches in peptides, as well as two HTI peptides are characterized by Ultrafast Spectroscopy in the visible and the infrared. The two HTI switches follow the reaction scheme published for other HTI compounds with a picosecond excited state reaction (τ1 ≈ 6 ps) and isomerization from Z to E with τ2 = 13 and 51 ps. As compared to the isolated chromophores, the isomerization reaction is slowed down in the chromopeptides to τ2 = 24 and 69 ps. For the smaller peptide containing 6 amino acids, the structural changes of the peptide moiety observed via the IR spectrum in the amide I band follow the isomerization of the molecular switch closely. In the larger cyclic chromopeptide, containing 20 amino acids and mimicking a β-hairpin structure in the Z-form of the chromophore, the peptide moiety also changes its structure during isomerization of the chromophore. However, the IR spectrum at the end of the observation period of 3 ns ...
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Light-switchable hemithioindigo-hemistilbene-containing peptides: Ultrafast Spectroscopy of the Z → E isomerization of the chromophore and the structural dynamics of the peptide moiety.
The journal of physical chemistry. B, 2012Co-Authors: Nadja Regner, Teja T Herzog, Karin Haiser, Christian Hoppmann, Michael Beyermann, Jorg Sauermann, Martin Engelhard, Thorben Cordes, Karola Rück-braun, Wolfgang ZinthAbstract:Two hemithioindigo–hemistilbene (HTI) derivatives, designed to operate as structural switches in peptides, as well as two HTI peptides are characterized by Ultrafast Spectroscopy in the visible and the infrared. The two HTI switches follow the reaction scheme published for other HTI compounds with a picosecond excited state reaction (τ1 ≈ 6 ps) and isomerization from Z to E with τ2 = 13 and 51 ps. As compared to the isolated chromophores, the isomerization reaction is slowed down in the chromopeptides to τ2 = 24 and 69 ps. For the smaller peptide containing 6 amino acids, the structural changes of the peptide moiety observed via the IR spectrum in the amide I band follow the isomerization of the molecular switch closely. In the larger cyclic chromopeptide, containing 20 amino acids and mimicking a β-hairpin structure in the Z-form of the chromophore, the peptide moiety also changes its structure during isomerization of the chromophore. However, the IR spectrum at the end of the observation period of 3 ns ...
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Light-Switchable Hemithioindigo–Hemistilbene-Containing Peptides: Ultrafast Spectroscopy of the Z → E Isomerization of the Chromophore and the Structural Dynamics of the Peptide Moiety B
The Journal of Physical Chemistry, 2012Co-Authors: Nadja Regner, Teja T Herzog, Karin Haiser, Christian Hoppmann, Michael Beyermann, Jorg Sauermann, Martin Engelhard, Thorben Cordes, K. Rück-braun, Wolfgang ZinthAbstract:Two hemithioindigo–hemistilbene (HTI) derivatives, designed to operate as structural switches in peptides, as well as two HTI peptides are characterized by Ultrafast Spectroscopy in the visible and the infrared. The two HTI switches follow the reaction scheme published for other HTI compounds with a picosecond excited state reaction (τ₁ ≈ 6 ps) and isomerization from Z to E with τ₂ = 13 and 51 ps. As compared to the isolated chromophores, the isomerization reaction is slowed down in the chromopeptides to τ₂ = 24 and 69 ps. For the smaller peptide containing 6 amino acids, the structural changes of the peptide moiety observed via the IR spectrum in the amide I band follow the isomerization of the molecular switch closely. In the larger cyclic chromopeptide, containing 20 amino acids and mimicking a β-hairpin structure in the Z-form of the chromophore, the peptide moiety also changes its structure during isomerization of the chromophore. However, the IR spectrum at the end of the observation period of 3 ns deviates significantly from the stationary difference spectrum. These signatures indicate that strong additional structural changes, e.g., breaking of interchain hydrogen bonds, also occur on longer time scales.
