scholarly journals Controlled ultrafast ππ*-πσ* dynamics in tryptophan-based peptides with tailored micro-environment

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Marius Hervé ◽  
Alexie Boyer ◽  
Richard Brédy ◽  
Isabelle Compagnon ◽  
Abdul-Rahman Allouche ◽  
...  
Keyword(s):  
Structural Dynamics ◽  
Potential Energy Surfaces ◽  
Molecular Ions ◽  
Microscopic Level ◽  
Nuclear Motion ◽  
Length Scale ◽  
Molecular Processes ◽  
Striking Increase ◽  
Order Of Magnitude ◽  
Energy Surfaces

AbstractUltrafast charge, energy and structural dynamics in molecules are driven by the topology of the multidimensional potential energy surfaces that determines the coordinated electronic and nuclear motion. These processes are also strongly influenced by the interaction with the molecular environment, making very challenging a general understanding of these dynamics on a microscopic level. Here we use electrospray and mass spectrometry technologies to produce isolated molecular ions with a controlled micro-environment. We measure ultrafast photo-induced ππ*-πσ* dynamics in tryptophan species in the presence of a single, charged adduct. A striking increase of the timescale by more than one order of magnitude is observed when changing the added adduct atom. A model is proposed to rationalize the results, based on the localized and delocalized effects of the adduct on the electronic structure of the molecule. These results offer perspectives to control ultrafast molecular processes by designing the micro-environment on the Angström length scale.

The photolysis of gaseous aldehydes. II. The decomposition of formyl and acetyl radicals

1956 ◽  
Vol 9 (1) ◽  
pp. 34 ◽  
Author(s):  
FH Dorman ◽  
AS Buchanan
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Kcal Mole ◽  
Correct Order ◽  
Order Of Magnitude ◽  
Energy Surfaces ◽  
Parameter Values

The potential energy surfaces for the decomposition of HCO, CH3CO, and COCl radicals have been constructed using Bawn's (1938, 1939) method with new parameter values. The values obtained for the energies of activation for decomposition were of the order of 26, 18, and 6 kcal mole-1 respectively. The CH3CO and COCl values agree with experimental estimates and consequently it is believed that the formyl value is of the correct order of magnitude.

Internal conversion and the crossing of molecular potential energy surfaces

1962 ◽  
Vol 268 (1335) ◽  
pp. 437-451 ◽  
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Internal Conversion ◽  
Careful Analysis ◽  
Molecular Potential ◽  
Order Of Magnitude ◽  
Molecular Potential Energy ◽  
Energy Surfaces ◽  
New Formula ◽  
Crossing Point

A re-examination is made of the Landau-Zener formula relating to the probability of an electronic jump near the crossing-point of two potential energy curves (or surfaces). Three cases are distinguished: discrete-discrete, discrete-continuum and continuum-continuum transitions. Different formulae are obtained for each of these cases. These formulae involve certain matrix elements of the interaction between the energy curves. A careful analysis is made of the order of magnitude of the terms that appear, and some corrections are made of previous work. It appears that the limits within which the original Landau-Zener formula is valid are seldom found in actual practice. A new formula (50) of greater validity is presented.

`Making the molecular movie': first frames

2010 ◽  
Vol 66 (2) ◽  
pp. 137-156 ◽  
Author(s):  
R. J. Dwayne Miller ◽  
Ralph Ernstorfer ◽  
Maher Harb ◽  
Meng Gao ◽  
Christoph T. Hebeisen ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Potential Energy ◽  
Structural Dynamics ◽  
Potential Energy Surfaces ◽  
Structural Changes ◽  
Single Shot ◽  
Sufficient Intensity ◽  
Energy Surfaces ◽  
Structural Probes

Recent advances in high-intensity electron and X-ray pulsed sources now make it possible to directly observe atomic motions as they occur in barrier-crossing processes. These rare events require the structural dynamics to be triggered by femtosecond excitation pulses that prepare the system above the barrier or access new potential energy surfaces that drive the structural changes. In general, the sampling process modifies the system such that the structural probes should ideally have sufficient intensity to fully resolve structures near the single-shot limit for a given time point. New developments in both source intensity and temporal characterization of the pulsed sampling mode have made it possible to make so-called `molecular movies',i.e.measure relative atomic motions faster than collisions can blur information on correlations. Strongly driven phase transitions from thermally propagated melting to optically modified potential energy surfaces leading to ballistic phase transitions and bond stiffening are given as examples of the new insights that can be gained from an atomic level perspective of structural dynamics. The most important impact will likely be made in the fields of chemistry and biology where the central unifying concept of the transition state will come under direct observation and enable a reduction of high-dimensional complex reaction surfaces to the key reactive modes, as long mastered by Mother Nature.

scholarly journals Diagonal Born-Oppenheimer Corrections to the Ground Electronic State Potential Energy Surfaces of Ozone: Improvement of Ab Initio Vibrational Band Centers for the 16O3, 17O3 and 18O3 Isotopologues

2020 ◽  
Author(s):  
Attila Tajti ◽  
Péter Szalay ◽  
Roman V. Kochanov ◽  
Vladimir G. Tyuterev
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Potential Energy Surfaces ◽  
Vibrational States ◽  
Theoretical Predictions ◽  
Order Of Magnitude ◽  
State Potential ◽  
Effective Models ◽  
Energy Surfaces ◽  
Mass Dependent

<div>Mass-dependent diagonal Born-Oppenheimer corrections (DBOC) to the ab initio electronic ground state potential energy surface for tseveral isotopologues of the ozone molecule are reported for the first time. The comparison with experimental band centers shows a significant improvement of the accuracy with respect to the best Born-Oppenheimer (BO) ab initio calculations reducing the total root-mean-squares (calculated - observed) deviations by about factor of two. For the set of 16O3 vibrations up to five bending and four stretching quanta, the mean (calculated - observed) deviations drop down from 0.7 cm-1 (BO) to about 0.1 cm-1, with the most pronounced improvement seen for bending states and for mixed bend-stretch polyads. In case of bending band centers directly observed under high spectral resolutions, the errors are reduced by more than order of magnitude from observed levels, approaching nearly experimental accuracy. New sets of ab initio vibrational states can be used for improving spectroscopic effective models for analyses of observed high-resolution spectra, particularly in cases of accidental resonances with ,,dark'' states requiring accurate theoretical predictions.</div>

Potential energy surfaces and dissociation mechanisms of molecular ions

1980 ◽  
Vol 77 ◽  
pp. 719-724 ◽  
Author(s):  
J.C. Lorquet ◽  
D. Dehareng ◽  
C. Sannen ◽  
G. Raseev
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Molecular Ions ◽  
Dissociation Mechanisms ◽  
Energy Surfaces

FINITE-TEMPERATURE SIMULATION OF ABSORPTION SPECTRA IN SMALL ARGON-CLUSTER IONS ${\rm Ar}_n^ + $(n=3, 4, 8, 13, AND 19)

1996 ◽  
Vol 03 (01) ◽  
pp. 211-215 ◽  
Author(s):  
M. GRIGOROV ◽  
F. SPIEGELMANN
Keyword(s):  
Absorption Spectra ◽  
Finite Temperature ◽  
Potential Energy Surfaces ◽  
Monte Carlo Algorithm ◽  
Cluster Ions ◽  
Nuclear Motion ◽  
Spin Orbit Coupling ◽  
Metropolis Monte Carlo ◽  
Energy Surfaces

We report finite-temperature simulations of the absorption spectra of argon-cluster ions using a diatomics in molecules (DIM) Hamiltonian (including spin-orbit coupling) for the determination of the potential-energy surfaces (PES), a point-charge approximation for the dipole transition moments and a Metropolis Monte-Carlo algorithm for the nuclear motion. The dependency of the absorption spectrum on cluster size (3≤n≤19) and on temperature (100 K≤T≤500 K) is analyzed.

scholarly journals Diagonal Born-Oppenheimer Corrections to the Ground Electronic State Potential Energy Surfaces of Ozone: Improvement of Ab Initio Vibrational Band Centers for the 16O3, 17O3 and 18O3 Isotopologues

2020 ◽  
Author(s):  
Attila Tajti ◽  
Péter Szalay ◽  
Roman V. Kochanov ◽  
Vladimir G. Tyuterev
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Potential Energy Surfaces ◽  
Vibrational States ◽  
Theoretical Predictions ◽  
Order Of Magnitude ◽  
State Potential ◽  
Effective Models ◽  
Energy Surfaces ◽  
Mass Dependent

<div>Mass-dependent diagonal Born-Oppenheimer corrections (DBOC) to the ab initio electronic ground state potential energy surface for tseveral isotopologues of the ozone molecule are reported for the first time. The comparison with experimental band centers shows a significant improvement of the accuracy with respect to the best Born-Oppenheimer (BO) ab initio calculations reducing the total root-mean-squares (calculated - observed) deviations by about factor of two. For the set of 16O3 vibrations up to five bending and four stretching quanta, the mean (calculated - observed) deviations drop down from 0.7 cm-1 (BO) to about 0.1 cm-1, with the most pronounced improvement seen for bending states and for mixed bend-stretch polyads. In case of bending band centers directly observed under high spectral resolutions, the errors are reduced by more than order of magnitude from observed levels, approaching nearly experimental accuracy. New sets of ab initio vibrational states can be used for improving spectroscopic effective models for analyses of observed high-resolution spectra, particularly in cases of accidental resonances with ,,dark'' states requiring accurate theoretical predictions.</div>

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