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Exptl. evidence is presented for the process of MO Rydbergization postulated by Mulliken, whereby an antibonding orbital continuously changes its character from predominantly Rydberg to predominantly valence on its way to dissocn. By matrix-isolation spectroscopy of the ~A1B1 state of H2O in Ar and Kr matrixes and in ice, the authors show that the absorption threshold behaves like a valence transition while the max. has a behavior typical of Rydberg transitions in condensed matter, in agreement with the pre

Using broadband UV-vis femtosecond transient absorption and fluorescence up-conversion, we investigate the interaction between the haem moiety of ferric and ferrous Horse heart Cytochrome c and its single Tryptophan (Trp) residue and the energy dissipation ...

Steady-state and picosecond (ps) fluorescence studies of wild-type bacteriorhodopsin (wt-bR) and of a nonisomerizing analog locked in the all-trans configuration have been performed. Extending earlier work done by femtosecond absorption spectroscopy, we observe a strong similarity between both proteins in both fluorescence spectra and Stokes shift thus confirming the previous result that the fluorescent state I460 of the native bR proteins is in the all-trans configuration. Comparison of the spectra of fluo

Electron transfer and subsequent charge separation across donor-acceptor heterojunctions remain the most important areas of study in the field of third-generation photovoltaics. In this context, it is particularly important to unravel the dynamics of indiv ...

The spectroscopy of Hg2 mols. in Ne matrixes was studied using absorption, excitation and emission spectroscopy. Emission spectra show fluorescence from the lowest A0g+ and the B1g states, sepd. by .apprx.1500 cm-1, to the ground state X0+g. Their excitation spectra show clearly the absorption bands of the D1u and F0u+ states. The relaxation processes leading to the B and A emission bands are discussed. At higher excitation laser power, emission from the G0u+ state to the ground state is also obsd. Also, se

A theor. model is presented to account for the Fano-like interference lineshapes on multiphonon continua in the electronic spectrum of NO in rare-gas solids. The model is based on the coupling of the optical transitions to 1 single local mode, while the latter is coupled to lattice modes. The model complements the original Fano theory by considering the finite lifetime of the continuum states. Lineshapes are simulated for the case of the interference between the B(v = 12) valence level and the C(v = 0) Rydb

Structural dynamics in solid hydrogens is impulsively triggered by femtosecond excitation of the lowest Rydberg state of the NO impurity. The resulting charge redistribution induces a local radial deformation of the medium ("bubble" formation) around the impurity. The dynamics of bubble expansion and the ensuing medium response are probed in real-time by pump-probe spectroscopy. The results show that bubble formation is a one-way process without recurrence of the cage motion and is complete in .apprx.1-2

The authors present the case for exploiting time-resolved x-ray absorption to study structural dynamics in the liq. phase. With this aim in mind and considering the large differences between absorption coeffs. in the optical and the x-ray domains as well as the x-ray absorption cross sections due to unexcited species, the authors have estd. the anticipated signal-to-noise ratio (S/N) under realistic conditions with femtosecond laser pump pulses and synchrotron radiation x-ray probe pulses. As a model system

Changes in electronic structure are the source of structural modifications in photochem. and photobiol. processes, occurring at ultrafast time scales (between femto- and picosecond times). An original method to probe these changes based upon a pump probe m ...

Catalase and methaemoglobin have very similar haem groups, which are both ferric, yet catalase decomposes hydrogen peroxide to water and oxygen very efficiently, while methaemoglobin does not. Structural studies have attributed this behaviour to their diff ...

The fluorescence-excitation and fluorescence spectra as well as the fluorescence decay times were recorded for Hg atoms excited to the 61P1 state by synchrotron radiation in Ar, Kr, Xe, N2, and CH4 matrixes and in Ar matrixes with a low NH3 content. Sequential decays from the 61P1 to different 63PJ levels involve the intersystem crossing and intramultiplet relaxation, the dependence of the relaxation rate on the properties of the matrix being different for the 2 mechanisms. [on SciFinder (R)]

Energy- and time-resolved IR emission spectra of NO trapped in Kr and Xe matrixes following excitation by an ArF laser were recorded. In Kr matrixes, the ground-state levels are predominantly populated by radiative decay from the a 4P state. The Xe matrixes ground-state v - v - 2 IR emission bands were obsd. for v = 22-3, confirming that in the NO/Xe system most of the excited-state energy is dissipated nonradiatively into the ground state. The IR bands show typical radiative decay times in the ms range but

Chirality is a structural property of molecules lacking mirror symmetry that has strong implications in diverse fields, ranging from life sciences to materials science. Chirality-sensitive spectroscopic methods, such as circular dichroism, exhibit weak sig ...

A review. Time-resolved X-ray absorption fine structure (XAFS) spectroscopy with picosecond temporal resoln. is a new method to observe electronic and geometric structures of short-lived reaction intermediates. It combines an intense femtosecond laser sour ...

Excitation of the A(3ss) Rydberg state of NO leads to an extensive rearrangement of the environment, which was studied by classical mol. dynamics simulations and normal mode anal., using pair potentials from the literature. The medium response is independent of the details at long range of the excited state NO A-Ar potential, stressing the fact that it is mainly driven by the short range repulsive forces between the Rydberg electron and the matrix atoms. The authors establish the inertial character of the 1

The L-3 X-ray absorption spectrum of aqueous iodide is reported, and its EXAFS is compared to theoretical spectra reconstructed from the radial distribution function of the iodide hydration obtained from classical, hybrid Quantum Mechanics Molecular Mechanics, (QM/MM) and full quantum (density functional theory, DFT) molecular dynamics simulations. Since EXAFS is mainly sensitive to short distances around the iodide ion, it is a direct probe of the local solvation structure. The comparison shows that QM/MM

Broadband transient absorption (TA) spectroscopy, three-pulse photon echo peak shift (3PEPS), and anisotropy decay measurements were used to study the solvation dynamics in bulk water and interfacial water at ZrO2 surfaces, using Eosin Y as a probe. The 3P ...

The electronic properties of correlated insulators are governed by the strength of Coulomb interactions, enabling the control of electronic conductivity with external stimuli. This work highlights that the strength of electronic correlations in nickel oxide (NiO), a prototypical charge-transfer insulator, can be coherently reduced by tuning the intensity of an optical pulse excitation. This weakening of correlations persists for hundreds of picoseconds and exhibits a recovery time independent of photodoping

Structural changes of the Fe(II)-tris-bipyridine ([FeII(bpy)3]2+) complex induced by ultrashort pulse excitation and population of its short-lived (?0.6 ns) quintet high spin state were detected by picosecond x-ray absorption spectroscopy. The structural r ...

The resonance Raman overtone progressions of I2 in liq. Xe following excitation of the B state are discussed, and compared with similar data in solid Ar. It is shown that the Raman contribution from the B state is damped by predissocn. within one recurrence and the Raman emission can be treated as that of an outgoing wave packet crossing over to purely repulsive B'', a, and a' states. The potential curve crossing can be localized in space and time from the Raman data. Predissocn. to B" is important, esp. f

Majed Chergui

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Experimental evidence to Rydbergization of antibonding molecular orbitals

Energy transfer and relaxation mechanisms in Cytochrome c

Spectral and kinetic fluorescence properties of native and nonisomerizing retinal in bacteriorhodopsin

Charge separation and carrier dynamics in donor-acceptor heterojunction photovoltaic systems

Spectroscopy and energy relaxation processes of Hg2 and Hg in solid Ne

Theoretical description of interference effects in the absorption spectra of NO in rare-gas matrixes

Ultrafast Structural dynamics in solid hydrogens: A model for condensed phase quantum systems

Towards structural dynamics in condensed chemical systems exploiting ultrafast time-resolved x-ray absorption spectroscopy

Time-resolved X-ray absorption spectroscopy

RETRACTED: On the enzymatic activity of catalase: an iron L-edge X-ray absorption study of the active centre

Mechanisms of the Electronic Relaxation of the Hg(1P1) State in Low-Temperature Matrixes

Intramolecular electronic-to-vibrational energy conversion in NO trapped in Xe matrices

Hard X-ray helical dichroism of disordered molecular media

Exploiting EXAFS and XANES for time-resolved molecular structures in liquids

The medium response to an impulsive redistribution of charge in solid argon: molecular dynamics simulations and normal mode analysis

The solvent shell structure of aqueous iodide: X-ray absorption spectroscopy and classical, hybrid QM/MM and full quantum molecular dynamics simulations

Aqueous Solvation Dynamics at Metal Oxide Surfaces

Dynamic control of electron correlations in photodoped charge-transfer insulators

Structural Determination of a Short-Lived Excited Iron(II) Complex by Picosecond X-Ray Absorption Spectroscopy

Ultrafast dynamics of the B state of I2 in condensed rare gases