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Ion-neutral chemistry in the sub-Kelvin regime

English title Ion-neutral chemistry in the sub-Kelvin regime
Applicant Willitsch Stefan
Number 140834
Funding scheme SNSF Professorships
Research institution Physikalische Chemie Departement Chemie Universität Basel
Institution of higher education University of Basel - BS
Main discipline Physical Chemistry
Start/End 01.09.2012 - 31.08.2014
Approved amount 578'299.00
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Keywords (7)

cold molecules; laser cooling; cold chemistry; ion traps; chemical reaction dynamics; ion-molecule chemistry; Coulomb crystals

Lay Summary (English)

Lead
Lay summary
Recent advances in the preparation of "cold" molecules and ions at very low temperatures T<<1 K in the gas phase have opened up perspectives to study chemical reactions in a new physical regime. In conjunction with recently established techniques for the simultaneous control of the internal (rotational-vibrational) motion of the cold molecules, it has become possible not only to investigate, but also to control chemical processes at a level of accuracy which has not been possible before.

The present project aims at investigating chemical reactions of atomic and molecular ions with neutral atoms at collision energies corresponding to the range 1 mK-1 K (often called the "cold regime") and thereby realising full control over the internal motion (quantum state) of the reaction partners. These objectives will be reached by extending a recently developed "hybrid trap" for the simultaneous trapping and cooling of atomic ions and neutral atoms by a recently developed method for the state-selected generation of molecular ions. Subsequent cooling of the motion of the ions will enable the study of reactive processes with ultracold Rb atoms down to mK energies.

In a first step, we will study the dynamics of reactive collisions of simple systems, i.e., atomic ions and ultracold atoms to characterise general features of cold ionic collisions. These include light-assisted processes such as radiative charge exchange and molecule formation. Our experiments will also serve to test ion-neutral chemistry models in the cold regime. Subsequently, we will enhance the scope of our studies to molecular collision partners and investigate reactive processes between state-selected molecular ions such as nitrogen and bromine molecular ions and ultracold Rb atoms. The aim is to to elucidate molecular phenomena in cold ionic collisions, in particular electron transfer and radiation-driven processes. Finally, we will take the first steps to extend our studies to reactions of polyatomic ions such as water, ammonia and carbon dioxide.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Chemical reactions of conformationally selected 3-aminophenol molecules in a beam with Coulomb-crystallized Ca plus ions
Roesch Daniel, Willitsch Stefan, Chang Yuan-Pin, Kuepper Jochen (2014), Chemical reactions of conformationally selected 3-aminophenol molecules in a beam with Coulomb-crystallized Ca plus ions, in JOURNAL OF CHEMICAL PHYSICS, 140(12), 124202.
Ion-neutral chemistry at ultralow energies: dynamics of reactive collisions between laser-cooled Ca+ ions and Rb atoms in an ion-atom hybrid trap
Hall Felix H. J., Eberle Pascal, Hegi Gregor, Raoult Maurice, Aymar Mireille, Dulieu Olivier, Willitsch Stefan (2013), Ion-neutral chemistry at ultralow energies: dynamics of reactive collisions between laser-cooled Ca+ ions and Rb atoms in an ion-atom hybrid trap, in MOLECULAR PHYSICS, 111(14-15), 2020-2032.
Light-assisted cold chemical reactions of barium ions with rubidium atoms
Hall Felix H. J., Aymar Mireille, Raoult Maurice, Dulieu Olivier, Willitsch Stefan (2013), Light-assisted cold chemical reactions of barium ions with rubidium atoms, in MOLECULAR PHYSICS, 111(12-13), 1683-1690.
MOLECULAR PHYSICS Ultracold menage a trois
Willitsch Stefan (2013), MOLECULAR PHYSICS Ultracold menage a trois, in NATURE PHYSICS, 9(8), 461-462.
Specific Chemical Reactivities of Spatially Separated 3-Aminophenol Conformers with Cold Ca+ Ions
Chang Yuan-Pin, Dlugolecki Karol, Küpper Jochen, Rösch Daniel, Wild Dieter, Willitsch Stefan (2013), Specific Chemical Reactivities of Spatially Separated 3-Aminophenol Conformers with Cold Ca+ Ions, in Science, 342(6254), 98.
Ultracold ménage a trois
Willitsch Stefan (2013), Ultracold ménage a trois, in Nature Physics, 9, 461.
Millikelvin Reactive Collisions between Sympathetically Cooled Molecular Ions and Laser-Cooled Atoms in an Ion-Atom Hybrid Trap
Hall Felix H. J., Willitsch Stefan (2012), Millikelvin Reactive Collisions between Sympathetically Cooled Molecular Ions and Laser-Cooled Atoms in an Ion-Atom Hybrid Trap, in PHYSICAL REVIEW LETTERS, 109(23), 233202.

Collaboration

Group / person Country
Types of collaboration
Deutsches Elektronen-Synchrotron Germany (Europe)
- Publication
Laboratoire Aime-Cotton du CNRS France (Europe)
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
557. WE Hereaus Workshop ”Trapped ions meet cold atoms” Talk given at a conference Chemistry in hybrid traps: next-generation experiments 27.03.2014 Bad Honnef, Germany Willitsch Stefan;
Workshop on Cold and Ultracold Molecules Talk given at a conference New avenues with Coulomb-crystallized ions 04.11.2013 Granada, Spain Willitsch Stefan;
IonTech 2 Workshop Talk given at a conference Cold chemistry with atomic and molecular ions in an ion-atom hybrid trap 23.10.2013 Paris, France Willitsch Stefan;
Leopoldina Symposium on Spectroscopy and Dynamics Talk given at a conference Chemistry with cold ions 11.09.2013 Zürich, Switzerland Willitsch Stefan;
International School of Physics Enrico Fermi Talk given at a conference Cold atoms and ions 20.07.2013 Varenna, Italy Willitsch Stefan;
25. International Symposium on Molecular Beams Talk given at a conference Chemistry with Coulomb-crystallized ions in traps 09.06.2013 Prag, Czech Republic Willitsch Stefan;
245. National Meeting of the American Chemical Society Talk given at a conference Cold and Controlled Chemistry with Coulomb-crystallized ions 09.04.2013 New Orleans, United States of America Willitsch Stefan;
KITP Conference on New Science with Ultracold Molecules Talk given at a conference Cold and Controlled Chemistry with Coulomb-crystallized atomic and molecular ions 11.03.2013 Santa Barbara, United States of America Willitsch Stefan;
ESF Conference on Cold and Ultracold Molecules Talk given at a conference Cold reactive collisions in ion-atom hybrid traps 18.11.2012 Obergurgl, Austria Hall Felix Henry Joynson; Willitsch Stefan;
19. European Conference on the Dynamics of Molecular Systems (MOLEC) Talk given at a conference Cold and controlled chemistry with Coulomb-crystallised atomic and molecular ions in traps 13.09.2012 Oxford, Great Britain and Northern Ireland Willitsch Stefan;


Self-organised

Title Date Place
2. Workshop on Cold Molecular Ions 02.09.2013 Arosa, Switzerland
Rigi Workshop 2013 20.01.2013 Rigi Kulm, Switzerland

Awards

Title Year
Molecular Physics Young Author's Prize 2014

Associated projects

Number Title Start Funding scheme
118921 Quantum-state selected cold molecular ions: preparation, properties, spectroscopy and chemistry 01.09.2008 SNSF Professorships
157874 Conformationally controlled chemistry 01.09.2015 SNSF Consolidator Grants

Abstract

Recent advances in the preparation of "cold" molecules and ions at very low translational energies (E_trans/k_B<1 K) in the gas phase have opened up perspectives to study chemical reactions in a new physical regime. In conjunction with recently established techniques for the simultaneous preparation of the internal, i.e., rotational-vibrational, quantum state of the cold molecules, it has become possible not only to investigate, but also to control chemical processes at a level of accuracy which has not been possible before. The present project aims at investigating chemical reactions of atomic and molecular ions with neutral atoms at collision energies E_coll/k_B>1 mK (the "cold regime"). By simultaneously preparing the reaction partners in a well-defined internal quantum state, ion-neutral chemical processes will be studied with full quantum-state resolution over a collision energy range spanning up to six orders magnitude. These objectives will be reached by extending a recently developed "hybrid trap" for the simultaneous trapping and cooling of atomic ions and neutral atoms with a threshold-photoionisation setup for the state-selected generation of molecular ions. Subsequent sympathetic cooling of their translational motion will enable the study of reactive processes with ultracold Rb atoms down to mK energies. Besides taking ion-neutral reaction studies into a new physical domain, the experimental tools established in the present project will also enable unprecedented levels of control over reactive processes with molecular ions by precisely determining their quantum state and position in space as well as accurately controlling the collision energy with the neutrals. In a first step, we will study the dynamics of reactive collisions of simple systems, i.e., atomic ions and ultracold atoms. Using the model reactions Ca^+ + Rb and Ba^+ + Rb, we will characterise general features of cold ionic collisions. These include light-assisted processes such as radiative charge exchange and molecule formation. Our experiments will also serve to test ion-neutral scattering models in the cold regime. Subsequently, we will enhance the scope of our studies to molecular collision partners and investigate reactive processes between state-selected molecular ions such as N_2^+ and Br_2^+ and ultracold Rb atoms. The aim is to to elucidate molecular phenomena in cold ionic collisions, in particular electron transfer and radiation-driven processes. Finally, we will take the first steps to extend our studies to reactions of polyatomic ions such as H_2O^+, CO_2^+ and NH_3^+.
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