Publications associées à Théorie des collisions

Molecular dynamics simulations of the evaporation of hydrated ions from aqueous solution

Although important for atmospheric processes and gas-phase catalysis, very little is known about the hydration state of ions in the vapor phase. Here we study the evaporation energetics and kinetics of a chloride ion from liquid water by molecular dynamics ...

NATURE PORTFOLIO2022

Landing Proteins on Graphene Trampoline Preserves Their Gas-Phase Folding on the Surface

Klaus Kern, Stephan Rauschenbach, Sven Alexander Szilagyi, Hannah Julia Ochner

Molecule-surface collisions are known to initiate dynamics that lead to products inaccessible by thermal chemistry. These collision dynamics, however, have mostly been examined on bulk surfaces, leaving vast opportunities unexplored for molecular collision ...

AMER CHEMICAL SOC2023

Low-energy stereodynamics of ion-forming reactions

Junwen Zou

In this thesis, an experimental study of low-temperature stereodynamics in the reactive scattering of Ne(3P2) + X collisions (X = Ar, Kr, Xe, CO and N2) is presented. The steric effect of Ne(3P2) in these reactions is observed experimentally using a contro ...

EPFL2021

Intermolecular Pd(0)-Catalyzed Atropo-enantioselective C-H Arylation of Heteroarenes and Other Investigations into the Enantioselective Activation of Challenging C(sp3)-H Bonds

Qui-Hien Nguyen

The direct construction of stereogenic axes by enantioselective C-H arylation has been regarded as a very challenging transformation. Very few examples have been reported, despite the indisputable straight-forwardness of the methodology. This is due to the ...

EPFL2021

Photoisomerization of Linear and Stacked Isomers of a Charged Styryl Dye: A Tandem Ion Mobility Study

Eduardo Carrascosa Casado

The photoisomerization behavior of styryl 9M, a common dye used in material sciences, is investigated using tandem ion mobility spectrometry (IMS) coupled with laser spectroscopy. Styryl 9M has two alkene linkages, potentially allowing for four geometric i ...

AMER CHEMICAL SOC2021

Studies of cold chemistry in crossed and merged neutral beams

Silvia Tanteri

In this thesis we present the design of two setups to study low-energy collisions between neutral species: an electron velocity map imaging for chemi-ionisation reactions and a merged electrostatic guide for polar molecules scattering. In the past few yea ...

EPFL2021

Study of He/Ne+Ar, Kr, N2, H2, D2 Chemi-Ionization Reactions by Electron Velocity-Map Imaging

Andreas Osterwalder, Sean Dennis Steven Gordon, Junwen Zou, Silvia Tanteri

The chemi-ionization of Ar, Kr, N2, H2, and D2 by Ne(3P2) and of Ar, Kr, and N2 by He(3S1) was studied by electron velocity map imaging (e-VMI) in a crossed molecular beam experiment. A curved magnetic hexapole was used to state-select the metastable speci ...

2021

Atomistic dynamics of elimination and nucleophilic substitution disentangled for the F- + CH3CH2Cl reaction

Eduardo Carrascosa Casado

Chemical reaction dynamics are studied to monitor and understand the concerted motion of several atoms while they rearrange from reactants to products. When the number of atoms involved increases, the number of pathways, transition states and product chann ...

NATURE PORTFOLIO2021

Investigation of the low-energy stereodynamics in the Ne(3P2) + N2, CO reactions

Andreas Osterwalder, Junwen Zou

We report on an experimental investigation of the low-energy stereodynamics of the energy transfer reactions Ne(3P2) + X, producing Ne(1S) + X+ and [Ne–X]+ (X = N2 or CO). Collision energies in the range 0.2 K–700 K are obtained by using the merged beam te ...

2020

The stereodynamics of ion forming reactions

Andreas Osterwalder, Sean Dennis Steven Gordon

Energy transfer reactions occur in all areas of chemistry. One fundamental form of this is demonstrated by reactions in which an electronically excited atom transfers energy to a neutral, resulting in spontaneous ionisation, potentially combined with compl ...

2020

Toward catchment hydro-biogeochemical theories

Andrea Rinaldo, Paolo Benettin, Ilja van Meerveld, Li Li

Headwater catchments are the fundamental units that connect the land to the ocean. Hydrological flow and biogeochemical processes are intricately coupled, yet their respective sciences have progressed without much integration. Reaction kinetic theories tha ...

WILEY2020

High-Current Low-Voltage Power Supply for Superconducting Magnets

Émilien Luc Henri Coulinge

In the wide range of applications for power supplies, the ones dedicated to feeding superconducting magnets occupy a niche. This particular kind of magnets has the intrinsic property of having zero resistance, and is only used in high-end facilities for fu ...

EPFL2020

Unexpected Indirect Dynamics in Base-Induced Elimination

Eduardo Carrascosa Casado

Base-induced elimination (E2) and bimolecular nucleophilic substitution (S(N)2) are two of the most versatile reactions that are important in preparative organic chemistry. These stereospecific reactions are often found in direct competition with each othe ...

AMER CHEMICAL SOC2019

Combined Nuclear Magnetic Resonance and Molecular Dynamics Study of Methane Adsorption in M-2(dobdc) Metal-Organic Frameworks

Berend Smit, Efrem Daniel Braun, Rocio Mercado, Amber Kashan Mace

We examine the diffusion of methane in the metal organic frameworks M-2(dobdc) (M = Mg, Ni, Zn; dobdc(4-) = 2,5-diwddo-1,4-benzenedicarboxylate) as a function of methane loading through a combination of nuclear magnetic resonance and molecular dynamics sim ...

2019

Bimolecular charge transfer reactions at and through the liquid-liquid interface

Grégoire Clément Gschwend

Interfaces are ubiquitous in Nature. Among them, soft interfaces are essential constituents of biological tissues. Indeed, many electrochemical reactions and phenomena take place at these interfaces. In this respect, ITIES are an interesting model to study ...

EPFL2019

Particle transport at arbitrary timescales with Poisson-distributed collisions

Ambrogio Fasoli, Ivo Furno, Paolo Ricci, Marcelo Baquero Ruiz, Fabian Manke

We develop a model to investigate the time evolution of the mean location and variance of a random walker subject to Poisson-distributed collisions at constant rate. The collisions are instantaneous velocity changes where a new value of velocity is generat ...

2019

Quantum-state-controlled channel branching in cold Ne(3P2)+Ar chemi-ionization

Andreas Osterwalder, Sean Dennis Steven Gordon, Junwen Zou, Silvia Tanteri

A prerequisite to gain a complete understanding of the most basic aspects of chemical reactions is the ability to perform experiments with complete control over the reactant degrees of freedom. By controlling these, details of a reaction mechanism can be i ...

2018

Collisional damping rates for electron plasma waves reassessed

Stephan Brunner, Trach-Minh Tran

Collisional damping of electron plasma waves, the primary damping for high phase velocity waves, is proportional to the electron-ion collision rate, nu(ei,th). Here, it is shown that the damping rate normalized to nu(ei,th) depends on the charge state, Z, ...

Amer Physical Soc2017

Importance of rotationally inelastic processes in low-energy Penning ionization of CHF3

Andreas Osterwalder, Justinas Jankunas

Low energy reaction dynamics can strongly depend on the internal structure of the reactants. The role of rotationally inelastic processes in cold collisions involving polyatomic molecules has not been explored so far. Here we address this problem performin ...

American Institute of Physics2016

Experimental and Theoretical Studies of Low-Energy Penning Ionization of NH3, CH3F, and CHF3

Andreas Osterwalder, Justinas Jankunas

We present results from a joint theoretical and experimental study of the low-energy Penning ionization of NH3, CH3F, and CHF3 by metastable Ne(P-3(2)) and He(S-3(1)) atoms. We combine the merged neutral beams experiment, covering a range of collision ener ...

Wiley-Blackwell2016