2025-10-21

Department of Physics

How oxygen molecules neutralize each other – and why their vibrations matter

When positively and negatively charged oxygen molecules meet, they usually neutralize and fall apart into separate atoms. Using ultra-cold ion beams and advanced imaging, researchers have shown that most of these reactions produce oxygen atoms in their normal state, while a smaller fraction end up excited. The study reveals that tiny molecular vibrations can change how the reaction unfolds — a key insight for understanding processes in phenomena like lightning sprites and electrical discharges in air. The editors at Nature Communications have put together an Editors’ Highlights webpage of recent research called “Inorganic and physical chemistry” and are pleased to inform that the editor chose to feature your article, entitled “Vibrationally-dependent molecular dynamics in mutual neutralisation reactions of molecular oxygen ions”.

2025-10-16

Department of Physics

Air spirits occur high up in the Earth's atmosphere

High up in the Earth's atmosphere, so-called air spirits occur, which are a weather phenomenon consisting of a gigantic network of electric discharges with a lifetime of a many milliseconds giving rise to a varied range of visual shapes flickering in the night sky. Using the Swedish National Infrastructure, DESIREE, located at Stockholm University, the study was led by Senior Lecturer Rich Thomas and PhD student Mathias Poline at the physics department of SU, and in a collaboration with the US Air Force Office of Scientific Research.

2025-10-07

Department of Physics

Executive Vice-President Roxana Mînzatu, EU Commission, visited Fysikum

Roxana Mînzatu is leading the work on the Union of Skills. "My priority throughout this mandate will remain to encourage girls & women to pursue STEM careers." She was welcomed by Tony Hansson, Head of Fysikum. The visit to Stockholm University included a tour to the DESIREE laboratory in the AlbaNova building where she met the PhD's Rachel Poulose and Truly Rylander. The Dean Lena Mäler, presented statistics for gender and STEM at the of the Faculty of Science. Professor Sara Strandberg presented gender diversity at Fysikum. Professor Anna Sobek, Head of Department of Environmental Science, presented the TRACEE Master Program. The visit to Sweden lasted for two days.

2024-10-17

Six researchers share SEK 175 million from the Wallenberg Foundation

The importance of Arctic methane emissions for the climate, how matter is formed and broken down, evolutionary shifts in the plant kingdom, and new effective methods for producing bioactive substances that will meet future needs for medicines and advanced electronics. These are just a few examples of basic research at Stockholm University that has received funding from the Knut and Alice Wallenberg Foundation.

2024-10-15

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'.

2024-01-22

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.

2024-01-18

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.

2023-06-29

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.

2023-02-02

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.

2022-10-12

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.