Publications de Andreas Osterwalder

Publications associées (32)

Dynamics of gas phase Ne* + NH3 and Ne* + ND3 Penning ionisation at low temperatures

Andreas Osterwalder, Justinas Jankunas, Benjamin Bertsche

Two isotopic chemical reactions, Ne* + NH_3, and Ne* + ND_3, have been studied at low collision energies by means of a merged beams technique. Partial cross sections have been recorded for the two reactive channels, namely, Ne* + NH_3 → Ne + NH^+_3 + e −, ...

American Institute of Physics2014

Dynamics of individual rotational states in an electrostatic guide for neutral molecules

Andreas Osterwalder, Benjamin Bertsche

The guiding properties of individual rotational states of deuterated ammonia inside an electrostatic hexapole guide are presented. The guide is combined with resonance enhanced multiphoton ionization detection to assess the guiding probabilities and veloci ...

2011

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

Slow electron velocity-map imaging photoelectron spectra of the methoxide anion

Andreas Osterwalder

High resoln. anion photodetachment spectra are presented for the methoxide anion and its fully deuterated counterpart. The spectra were obtained with slow electron velocity-map imaging. Improved electron affinities are detd. for CH3O as 1.5690 +- 0.0019 eV ...

2006

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

A traveling wave decelerator for neutral polar molecules

Andreas Osterwalder

Recently, a decelerator for neutral polar molecules has been presented that operates on the basis of macroscopic, three-dimensional, traveling electrostatic traps [A. Osterwalder, S. A. Meek, G. Hammer, H. Haak, and G. Meijer, Phys. Rev. A 81, 051401 (2010 ...

American Institute of Physics2011

Study of the Ne(3P2) + CH3F Electron-Transfer Reaction below 1 K

Andreas Osterwalder, Justinas Jankunas, Benjamin Bertsche

Relatively little is known about the dynamics of electron-transfer reactions at low collision energy. We present a study of Penning ionization of ground-state methyl fluoride molecules by electronically excited neon atoms in the 13 μeV–4.8 meV (150 mK–56 K ...

Amer Chemical Soc2014

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

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

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

Low-temperature Collisions between Neutral Molecules in Merged Molecular Beams

Andreas Osterwalder, Justinas Jankunas, Benjamin Bertsche

We have developed an experiment for the investigation of neutral molecular collisions in the gas phase at temperatures as low as 100 mK. These low temperatures are obtained by merging two supersonic expansions, using an electric and a magnetic guide, and b ...

Schweizerische Chemische Gesellschaft2014

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

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

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

High resolution photoelectron spectra of carbon cluster anions and their monohydrides

Andreas Osterwalder

The smaller carbon cluster anions, Cn- (n = 2-11), and their monohydrides, CnH- have been studied previously using anion photoelectron spectroscopy. In many cases, vibrational structure is obsd., but much of the structure remains hidden due to the resoln. ...

2005

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

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

Andreas Osterwalder, Sean Dennis Steven Gordon, Junwen Zou, 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

Preparation of Translationally Cold Neutral Molecules

Andreas Osterwalder, Giulia Di Domenicantonio, Benjamin Bertsche

Efforts at EPFL to obtain translationally cold neutral molecules are described. Active deceleration of polar molecules is performed by confining the molecules in moving three-dimensional electrostatic traps, and by appropriately choosing the velocity of th ...

2011

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

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