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Research subject Atomic Physics

In atomic physics we performs fundamental experimental and theoretical research on inherent properties of atomic systems and on atomic collision processes in the broad sense.

The experiments are mostly carried out at the DESIREE facility at the Department of Physics, a very powerful facility for different types of experiments with ions from atoms, molecules and clusters at low temperatures. We also study antihydrogen and interactions between atoms and electromagnetic radiation on extremely short time scales (attoseconds). Our activities are connected to nearby fields of research, in particular to astrophysics but also to atmospheric sciences and biophysics on a molecular level.

Related research subject

Physics
Atomfysik

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Researchers

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Research groups

DESIREE

The Atomic Physics division is pursuing experimental research in atomic collision physics dealing with interactions of positively and negatively charged atomic ions, molecular ions such as fullerenes, polycyclic aromatic hydrocarbons (PAHs), biomolecules, and clusters.

DESIREE - experimental research in nuclear collision physics
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Research projects

Ab initio studies of reactive scattering processes

Quantum mechanical studies of reactive scattering processes are performed involving small reaction complexes in highly excited states where non-adiabatic effects are crucial. The theoretical model is tested by close collaboration with experiments.

Antimatter atoms and ions

We study methods to create and probe atoms and ions made of antimatter, with the purpose to test fundamental symmetries of nature.

Foto: CERN
Experiments with beams of cold stored ions in DESIREE

Mutual Neutralization (MN) is studied at the DESIREE ion-beam storage ring. In MN, an electron is transferred from a negative to a positive ion forming two neutral particles. This fundamental process is important in many natural environment.

DESIREE - experimentell forskning inom atomär kollisionsfysik
Few-body physics

We examin universal properties of certain three-body systems using theoretical and numerical methods.

Foto: CERN
Timing many-body effects in small quantum systems

When atomic systems are exposed to light it is the electrons that react first. They absorb the radiation and convert the photon energy into excitation and ionization. Ultra-short light pulses are tools to study this dynamics in real time.

Artistic illustration of how a train of attosecond pulses (blue) and a IR-laser pulse (red)

Courses and programmes

At the Department of Physics at Stockholm University, we offer high-quality education with a strong connection to frontier research. We promise exciting studies in tight student groups and with active researchers as your teachers.

Courses and programmes

Doctoral studies

At Fysikum there are four postgraduate subjects: physics, theoretical physics, chemical physics and medical radiation physics.

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News

Svante Jonsell, lektor i teoretisk atomfysik på Fysikum
Department of Physics

Svante researches antiatoms and antiions

After completing his PhD in Uppsala and later researching at Nordita in Copenhagen and Umeå University, he moved on to the University of Swansea, Wales. Eventually he returned to Sweden and Fysikum. He lives in Uppsala again and has two grown-up daughters who are studying biology and the history of ideas. “Since 2010, I have a lectureship at Fysikum and research on antiatoms and antiions. Many researchers are part of the international ALPHA collaboration, which have published an article in Nature Physics in January 2025.

Physics - Theme page
Bild på det interstellära molnet Carina-nebulosan tagen med hjälp av James Webb Space Telescope.NASA
Department of Physics

Six researchers share 175 million from the Wallenberg Foundation

Basic research at Stockholm University has been granted funding by the Knut and Alice Wallenberg Foundation. Henning Schmidt, Professor of Atomic Physics division at Fysikum, has received SEK 35,000,000 over five years for the project 'Making and breaking of molecular bonds'.

Kvinnliga fysiker på Kvinnodagen 2024
Department of Physics

International Women's Day 2024: Women in physics

March 8 is International Women's Day and today we want to highlight women in physics. There are many examples including Marie Curie, Maria Goeppert Mayer and Lise Meitner to Fabiola Gianotti and Lene Hau. We also mention some of the female professors of physics who belong to the Fysikum.

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Figur 2: En sällsynt vy inifrån det unika Double ElectroStatic Ion-Ring Experiment, DESIREE
Department of Physics

The mutual neutralization of hydronium and hydroxide

Using the unique DESIREE facility, researchers at Stockholm University and The Hebrew University of Jerusalem have for the first time been able to directly visualise the neutral products of the mutual neutralization of hydronium and hydroxide, and report three different product channels: two channels were attributed to a predominant electron-transfer mechanism, and a smaller channel was associated with proton transfer. The two-beam collision experiment is an important step toward understanding the quantum dynamics of this fundamental reaction. Their findings are published in the journal Science. A team of scientists led by Prof. Daniel Strasser at The Hebrew University in Israel joined with a team led by Dr. Richard Thomas at The Department of Physics at Stockholm University, to investigate this reaction using the DESIREE facility.

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N-O internuclear separation
Department of Physics

When Opposites Fatally Attract: The Mutual Neutralisation Story

One reaction involving atomic and molecular ions which is extremely difficult to measure and explore in detail is mutual neutralisation, where a positive ion and a negative ion meet up, and neutralise. Thanks to a unique ion storage ring device, DESIREE, in Stockholm Sweden, these oppositely charged ions can be stored and controlled, then merged together in a cryogenically cold environment where the MN reaction happens. Using a cutting edge camera, we identify the reaction products and reconstruct the moment these opposites became fatally attracted, and neutralised.

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Foto från CRP mötet
Department of Physics

Understanding the role of molecules in fusion plasmas

For a long time, physicists have been dreaming about using fusion processes to produce energy on earth. ITER is a giant fusion tokamak being built in France as a large collaboration of several nations. The idea for a joint fusion project was launched in 1985 and the construction has been underway since 2010. The International Atomic Energy Agency (IAEA) organizes Coordinated Research Projects (CRP) were experts on fusion plasma modeling as well molecular physicists working on theoretical calculations of molecular scattering processes are invited. Professor Åsa Larson, Atomic Physics division, participated in this confererence.

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Michael Gatchell, Postdoctoral Fellow, Fysikum
Department of Physics

Coronene molecules contribute to complex chemistry in space

Carbon forms the basis of all organic chemistry and thus the building blocks of life. There is increasing evidence that amino acids and other complex organic molecules can be formed in space and spread to planets through, e.g., comet impacts. Large carbon-based molecule such as coronene could play an important role in how such organic molecules are produced in astronomical environments. Michael Gatchell has been interested in understanding the universe for as long as he can remember. Here he tells us about his research at Atomic Physics division of Fysikum and new results can change how we imagine molecules such as coronene contribute to chemistry in space.

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Molecular structures of 1-cyanonaphtalene
Department of Physics

Yet another breakthrough for researchers at DESIREE!

An international collaboration led by Mark H. Stockett (Fysikum) and James N. Bull (University of East Anglia) last week published results from experiments conducted at the DESIREE infrastructure at Fysikum in Nature Communications. After decades of speculation and searching, astronomers have recently begun to identify complex Polycyclic Aromatic Hydrocarbon (PAH) molecules in interstellar clouds.

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Moa Kristiansson and Gustav Eklund, the DESIREE Group
Department of Physics

Precision electron affinity measurement in DESIREE

The electron affinity of an element is defined as the amount of energy released when an additional electron is bound to the system, which is—of course—equal to the energy needed to remove the negatively charged ion. An efficient way to determine electron affinities is to expose an ensemble of negative ions to a laser field and then vary the wavelength of the light to find the threshold for a signal relating to the photodetachment process separating an electron from the now neutralized atom. The longest wavelength where this happens corresponds to a photon energy equal to the electron affinity, so by finding the threshold and transforming from wavelength to photon energy one can determine the electron affinity.

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Departments and centres

Research in the subject is mainly carried out at Fysikum in the division of Atomic Physics.

Department of Physics