The Experts below are selected from a list of 196080 Experts worldwide ranked by ideXlab platform
Collet Eric - One of the best experts on this subject based on the ideXlab platform.
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Femtosecond photoswitching dynamics and microsecond thermal conversion driven by laser heating in FeIII spin-crossover solids.
Coordination Chemistry Reviews, 2016Co-Authors: Bertoni R., Lorenc Maciej, Tissot A., Boillot M.L., Collet EricAbstract:In this paper we review time-resolved studies of ultrafast light-induced spin-state switching, triggered by a Femtosecond laser flash,and the following out-of-equilibrium dynamics in FeIII spincrossover crystals. The out-of-equilibrium dynamics involves several steps, resulting fromthe ultrafast molecular photoswitchingof low-spin (LS) to high-spin (HS) states in solids. First, the transient HS state is reached within 200 Femtoseconds, and mayrapidly decayinto the stable LS state of the system. A second process at longer delay,associated with volume expansion, drives additional conversion to the HS state during the so-called elastic step occurring at nanosecond time scale. Finally,the laser heating process induces a temperature jump in the crystal that may result in a significant thermal population of the HS state on microsecond time scale. The photoswitching mechanism is of local nature and has linear dependenceon the excitation fluence, whereas the heating effect can macroscopically perturb the LS/HS equilibrium. We discuss similarities and differences between photoswitching dynamics in solution and in different crystals for which the thermal spin conversion is of more or less pronounced cooperative nature.
Richard Neutze - One of the best experts on this subject based on the ideXlab platform.
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opportunities and challenges for time resolved studies of protein structural dynamics at x ray free electron lasers
Philosophical Transactions of the Royal Society B, 2014Co-Authors: Richard NeutzeAbstract:X-ray free-electron lasers (XFELs) are revolutionary X-ray sources. Their time structure, providing X-ray pulses of a few tens of Femtoseconds in duration; and their extreme peak brilliance, delivering approximately 1012 X-ray photons per pulse and facilitating sub-micrometre focusing, distinguish XFEL sources from synchrotron radiation. In this opinion piece, I argue that these properties of XFEL radiation will facilitate new discoveries in life science. I reason that time-resolved serial Femtosecond crystallography and time-resolved wide angle X-ray scattering are promising areas of scientific investigation that will be advanced by XFEL capabilities, allowing new scientific questions to be addressed that are not accessible using established methods at storage ring facilities. These questions include visualizing ultrafast protein structural dynamics on the Femtosecond to picosecond time-scale, as well as time-resolved diffraction studies of non-cyclic reactions. I argue that these emerging opportunities will stimulate a renaissance of interest in time-resolved structural biochemistry.
Weiping Hu - One of the best experts on this subject based on the ideXlab platform.
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Femtosecond dynamics on excited state proton charge transfer reaction in 4 n n diethylamino 3 hydroxyflavone the role of dipolar vectors in constructing a rational mechanism
Journal of Physical Chemistry A, 2005Co-Authors: Pitai Chou, Shihchieh Pu, Yiming Cheng, Weishan Yu, Yuehchi Yu, Fatsai Hung, Weiping HuAbstract:The excitation behaviors for 4‘-N,N-diethylamino-3-hydroxyflavone (Ia) have been investigated via Femtosecond fluorescence upconversion approaches to gain detailed insights into the mechanism of the proton/charge-transfer coupling reaction. In polar solvents such as CH2Cl2 and CH3CN, in addition to a slow, solvent-polarity-dependent rate (a few tens of picoseconds-1) of excited-state intramolecular proton transfer (ESIPT) reported previously, early Femtosecond relaxation dynamics clearly reveal that the proton-transfer tautomer emission consists of a rise component of a few hundred Femtoseconds. The temporal spectral evolution at the time domain of zero to a few hundred Femtoseconds further resolves two distinct emission bands consisting of a proton-transfer tautomer emission and a time-dependent Stokes shifted emission. The results, in combination with ab initio calculations on the dipolar vectors for normal and tautomer species, lead us to unveil the importance of the relationship of the dipolar vectors...
Wilfried Wurth - One of the best experts on this subject based on the ideXlab platform.
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Time-resolved observation of band-gap shrinking and electron-lattice thermalization within X-ray excited gallium arsenide
Scientific Reports, 2015Co-Authors: Beata Ziaja, Nikita Medvedev, Victor Tkachenko, Theophilos Maltezopoulos, Wilfried WurthAbstract:Femtosecond X-ray irradiation of solids excites energetic photoelectrons that thermalize on a timescale of a few hundred Femtoseconds. The thermalized electrons exchange energy with the lattice and heat it up. Experiments with X-ray free-electron lasers have unveiled so far the details of the electronic thermalization. In this work we show that the data on transient optical reflectivity measured in GaAs irradiated with Femtosecond X-ray pulses can be used to follow electron-lattice relaxation up to a few tens of picoseconds. With a dedicated theoretical framework, we explain the so far unexplained reflectivity overshooting as a result of band-gap shrinking. We also obtain predictions for a timescale of electron-lattice thermalization, initiated by conduction band electrons in the temperature regime of a few eVs. The conduction and valence band carriers were then strongly non-isothermal. The presented scheme is of general applicability and can stimulate further studies of relaxation within X-ray excited narrow band-gap semiconductors.
Bertoni R. - One of the best experts on this subject based on the ideXlab platform.
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Femtosecond photoswitching dynamics and microsecond thermal conversion driven by laser heating in FeIII spin-crossover solids.
Coordination Chemistry Reviews, 2016Co-Authors: Bertoni R., Lorenc Maciej, Tissot A., Boillot M.L., Collet EricAbstract:In this paper we review time-resolved studies of ultrafast light-induced spin-state switching, triggered by a Femtosecond laser flash,and the following out-of-equilibrium dynamics in FeIII spincrossover crystals. The out-of-equilibrium dynamics involves several steps, resulting fromthe ultrafast molecular photoswitchingof low-spin (LS) to high-spin (HS) states in solids. First, the transient HS state is reached within 200 Femtoseconds, and mayrapidly decayinto the stable LS state of the system. A second process at longer delay,associated with volume expansion, drives additional conversion to the HS state during the so-called elastic step occurring at nanosecond time scale. Finally,the laser heating process induces a temperature jump in the crystal that may result in a significant thermal population of the HS state on microsecond time scale. The photoswitching mechanism is of local nature and has linear dependenceon the excitation fluence, whereas the heating effect can macroscopically perturb the LS/HS equilibrium. We discuss similarities and differences between photoswitching dynamics in solution and in different crystals for which the thermal spin conversion is of more or less pronounced cooperative nature.
