scholarly journals Analyzing Angular Distributions for Two-Step Dissociation Mechanisms in Velocity Map Imaging

2013 ◽  
Vol 117 (32) ◽  
pp. 7102-7106 ◽  
Author(s):  
Daniel B. Straus ◽  
Lynne M. Butler ◽  
Bridget W. Alligood ◽  
Laurie J. Butler
Keyword(s):  
Angular Distributions ◽  
Velocity Map Imaging ◽  
Step Dissociation ◽  
Dissociation Mechanisms

scholarly journals Interference stabilization of autoionizing states in molecular N2 studied by time- and angular-resolved photoelectron spectroscopy

2016 ◽  
Vol 194 ◽  
pp. 509-524 ◽  
Author(s):  
Martin Eckstein ◽  
Nicola Mayer ◽  
Chung-Hsin Yang ◽  
Giuseppe Sansone ◽  
Marc J. J. Vrakking ◽  
...  
Keyword(s):  
Decay Rate ◽  
Photoelectron Spectroscopy ◽  
Rydberg States ◽  
Electronic States ◽  
The Other ◽  
Photoelectron Spectra ◽  
Angular Distributions ◽  
Velocity Map Imaging ◽  
Imaging Spectrometer ◽  
Exponential Decay Rate

An autoionizing resonance in molecular N2 is excited by an ultrashort XUV pulse and probed by a subsequent weak IR pulse, which ionizes the contributing Rydberg states. Time- and angular-resolved photoelectron spectra recorded with a velocity map imaging spectrometer reveal two electronic contributions with different angular distributions. One of them has an exponential decay rate of 20 ± 5 fs, while the other one is shorter than 10 fs. This observation is interpreted as a manifestation of interference stabilization involving the two overlapping discrete Rydberg states. A formalism of interference stabilization for molecular ionization is developed and applied to describe the autoionizing resonance. The results of calculations suggest, that the effect of the interference stabilization is facilitated by rotationally-induced couplings of electronic states with different symmetry.

A velocity map imaging study of the photodissociation of the methyl iodide cation

2017 ◽  
Vol 19 (11) ◽  
pp. 7886-7896 ◽  
Author(s):  
S. Marggi Poullain ◽  
D. V. Chicharro ◽  
J. González-Vázquez ◽  
L. Rubio-Lago ◽  
L. Bañares
Keyword(s):  
Ab Initio ◽  
Methyl Iodide ◽  
Imaging Study ◽  
Velocity Map Imaging ◽  
Dissociation Mechanisms

The photodissociation dynamics of the methyl iodide cation has been studied using velocity map imaging and ab initio theory to disentangle the dissociation mechanisms.

Insights into atomic orbital polarization in polyatomic dissociation from DC slide velocity map imaging

2019 ◽  
Author(s):  
◽  
Hashini Chaya Weeraratna
Keyword(s):  
Chemical Reactivity ◽  
Atomic Orbital ◽  
Detection Methods ◽  
Angular Distributions ◽  
Velocity Map Imaging ◽  
Ion Imaging ◽  
Recoil Velocity ◽  
University Of Missouri ◽  
Photoelectron Imaging ◽  
The University

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] "The field of chemical reaction dynamics is based upon understanding the details of elementary chemical reactions. It seeks to answer fundamental questions such as, what pathways does the reaction follow? what product states are formed? what determines the energy disposal, and the angular distributions of the products? State-of-the-art experimental methods developed over time along with theoretical techniques and advanced computational methods provide a toolset to address these questions. Achieving deep insight into reaction mechanisms ultimately permits the control over their chemical reactivity. One way of apprehending these processes is to characterize the potential energy surface (PES) since they completely embody the forces between the constituent atoms. .. Photodissociation of small molecules has been studied using variety of detection methods, such as, photofragment translational spectroscopy, [4,5] Laser-induced fluorescence (LIF), [6] Doppler-related methods, [7] Rydberg tagging, [8,9] photofragment ion imaging [10] and photoelectron imaging. [11] Photofragment imaging is now the most widely used method to study photodissociation dynamics. In the simplest illustration, it maps the recoil velocity distribution of the state selected product onto a position sensitive detector plane and energy and the angular distributions information are extracted by reconstruction of the experimentally observed images. The main objective of the this work is to study the vector correlations of photodissociation using photofragment ion imaging technique."--Introduction.

Association/dissociation Mechanisms of Intrinsically Disordered Region of Protein Beyond Conformational Selection and Induced Fit

2019 ◽  
Author(s):  
Duy Phuoc Tran ◽  
Akio Kitao
Keyword(s):  
Free Energy ◽  
Transcriptional Activation ◽  
Binding Free Energy ◽  
Energy Structure ◽  
Induced Fit ◽  
Hydrogen Bond Formation ◽  
Conformational Selection ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Region ◽  
Dissociation Mechanisms

<p>We investigate association and dissociation mechanisms of a typical intrinsically disordered region (IDR), transcriptional activation subdomain of tumor repressor protein p53 (TAD-p53) with murine double-minute clone 2 protein (MDM2). Using the combination of cycles of association and dissociation parallel cascade molecular dynamics, multiple standard MD, and Markov state model, we are successful in obtaining the lowest free energy structure of MDM2/TAD-p53 complex as the structure very close to that in crystal without prior knowledge. This method also reproduces the experimentally measured standard binding free energy, and association and dissociation rate constants solely with the accumulated MD simulation cost of 11.675 μs, in spite of the fact that actual dissociation occurs in the order of a second. Although there exist a few complex intermediates with similar free energies, TAD-p53 first binds MDM2 as the second lowest free energy intermediate dominantly (> 90% in flux), taking a form similar to one of the intermediate structures in its monomeric state. The mechanism of this step has a feature of conformational selection. In the second step, dehydration of the interface, formation of π-π stackings of the side-chains, and main-chain relaxation/hydrogen bond formation to complete α-helix take place, showing features of induced fit. In addition, dehydration (dewetting) is a key process for the final relaxation around the complex interface. These results demonstrate a more fine-grained view of the IDR association/dissociation beyond classical views of protein conformational change upon binding.</p>

scholarly journals Anomaly in photoelectron angular distributions

2007 ◽  
Vol 76 (1) ◽  
Author(s):  
Jingtao Zhang ◽  
L. D. van Woerkom ◽  
Dong-Sheng Guo ◽  
R. R. Freeman
Keyword(s):  
Angular Distributions ◽  
Photoelectron Angular Distributions
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