Publications de Andreas Osterwalder

Ne*(3P2,0) + CO chemi-ionization reactions: Atomic alignment and molecular orientation effects

The present study exploits the recent formulation of the optical potential that provided an internally consistent representation of the interaction between Ne*(3P2,0) + CO reagents and Ne + CO+(X2Σ, A2Π) products. The coupling between neutral entrance and ...

2025

The optical potential for Ne*(3P2,0) + CO chemi-ionization reactions: Nature of the intermolecular forces and selective formation of CO+ in ground (2Σ) and excited (2Π) electronic states

Andreas Osterwalder, Junwen Zou

Ionization processes, promoted by the collisions of CO molecule with noble gas atoms electronically excited in a metastable state, as Ne*, are known as chemi-ionization (CHEMI) reactions. CHEMI reactions of CO have been experimentally investigated in vario ...

2025

Alignment of ND3 molecules in dc-electric fields (vol 160, 204305, 2024)

Andreas Osterwalder, Viet Le Duc

AIP Publishing2025

Alignment of ND3 molecules in dc-electric fields

Andreas Osterwalder, Junwen Zou, Viet Le Duc

The control of movement and orientation of gas-phase molecules has become the focus of many research areas in molecular physics. Here, ND3 molecules are polarized in a segmented, curved electrostatic guide and adiabatically aligned inside a rotatable mass ...

Aip Publishing2024

MARTEMIS: Martian Analog Research and Training Experiments on the Moon with International Simulations

Andreas Osterwalder

International Astronautical Federation (IAF)2024

Imaging of Chemical Kinetics at the Water–Water Interface in a Free-Flowing Liquid Flat-Jet

Andreas Osterwalder, Bruno Credidio

We present chemical kinetics measurements of the luminol oxidation chemiluminescence (CL) reaction at the interface between two aqueous solutions, using liquid jet technology. Free-flowing liquid microjets are a relatively recent development that have foun ...

2022

Ultimate control in chemistry

Andreas Osterwalder

Controlling reactions between molecules is a major fundamental goal in chemistry and doing so on the level of individual quantum states is very challenging. Now, control over the reactant state and full characterization of the product-state distribution of ...

2021

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

Andreas Osterwalder, Junwen Zou, Sean Dennis Steven Gordon, 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

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

Energy and orientation independence of the channel branching in Ne* + ND3 chemi-ionisation

Andreas Osterwalder, Sean Dennis Steven Gordon

Collisions of excited neon atoms with ammonia molecules can lead to two reaction processes, dissociative ionisation and Penning ionisation. Both processes result in the ionisation of the ammonia molecule and redistribution of the electronic energy into the ...

2019

Sub-Kelvin stereodynamics of the Ne(3P2)+N2 reaction

Andreas Osterwalder, Junwen Zou, Sean Dennis Steven Gordon

We present an experimental study of the low-energy stereodynamics of the Ne(3P2)+N2 reaction. Supersonic expansions of the two reactants are superposed in a merged beam experiment, where individual velocity control of the two beams allows us to reach avera ...

AMER PHYSICAL SOC2019

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

Andreas Osterwalder, Junwen Zou, Sean Dennis Steven Gordon, 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

Stereodynamics of Ne(3P2) reacting with Ar, Kr, Xe, and N2

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

Stereodynamics experiments of Ne(3P2) reacting with Ar, Kr, Xe, and N2 leading to Penning and associative ionization have been performed in a crossed molecular beam apparatus. A curved magnetic hexapole was used to state-select and polarize Ne(3P2) atoms w ...

2018

Energy dependent stereodynamics of the Ne(3P2)+Ar reaction

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

The stereodynamics of the Ne(3P2)+Ar Penning and Associative ionization reactions have been studied using a crossed molecular beam apparatus. The experiment uses a curved magnetic hexapole to polarise the Ne(3P2) which is then oriented with a shaped magnet ...

American Physical Society2017

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

Oriented O(3P2), Ne(3P2), and He(3S1) atoms emerging from a bent magnetic guide

Andreas Osterwalder, Justinas Jankunas

We describe our observation of strongly oriented total electronic angular momentum J in O(P-3(2)), Ne(P-3(2)), and He(S-3(1)) atoms emerging from a bent magnetic multipole guide, as measured by resonant multiphoton ionisation. This was contrary to our expe ...

Taylor & Francis2016

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

Merged neutral beams

Andreas Osterwalder

A detailed description of a merged beam apparatus for the study of low energy molecular scattering is given. This review is intended to guide any scientist who plans to construct a similar experiment, and to provide some inspiration in describing the appro ...

2015

Preparation of state purified beams of He, Ne, C, N, and O atoms

Andreas Osterwalder, Justinas Jankunas

The production and guiding of ground state and metastable C, N, and O atoms in a two-meter-long, bent magnetic guide are described. Pure beams of metastable He(3S1) and Ne(3P2), and of ground state N(4S3/2) and O(3P2) are obtained using an Even-Lavie valve ...

Amer Inst Physics2015