Making and breaking molecular bonds - in space and in the laboratory
Matter on Earth, on other planets and in space is made up of atoms that form molecules, liquids and solids through chemical bonds. But how do molecules form and how do they decompose?
Colliding ions bring answers
Making and Breaking Molecular Bonds investigates how bonds are formed and broken when a positively charged ion interacts with a negatively charged ion under well-controlled conditions. This knowledge will contribute to the understanding of phenomena ranging from the formation of stars to the functioning of DNA molecules.
Research Field: atomic, molecular and optical physics
Project: "Making and Breaking Molecular Bonds"
Main researcher: Henning Schmidt, professor of atomic physics at Stockholm University
Grant: SEK 35,000,000 over five years
The same conditions as at the birth of the stars
The research team studies atoms and molecules at very low temperatures, around 13 Kelvin or -260 °C, which is similar to the temperature of gas clouds in the so-called interstellar medium, where new stars and planetary systems are born.
“At such low temperatures, the molecules move slowly, which prevents many types of chemical reactions. However, if a collision occurs between a positively charged ion and a negatively charged ion, a so-called charge transfer process can take place. More energy is then available than when two neutral particles meet, which leads to bonds being broken and new molecules being formed,“ says Henning Schmidt, professor of atomic physics at the Department of physics and director of the national research infrastructure, DESIREE, at Stockholm University.
Combination of methods
By combining theory, modelling and experiments, the research group will develop detailed descriptions of the mechanisms that control reactive charge transfer processes, i.e. processes in which the structure or composition of colliding molecules changes at the same time as electrons are transferred from one ion to the other.
“Our hypothesis is that these processes are of great importance for the growth of molecules in the interstellar medium, where the temperature of the dilute gas is very low, but where atoms and molecules can still be ionized by various forms of radiation,“ says Henning Schmidt.
Advanced research infrastructure
The research team plans to study the process using DESIREE's two electrostatic storage rings, where ions with opposite charges are stored in separate rings. In a common straight section, the ions move together in the same direction, and collisions between the ions occur at low relative velocities. The neutral molecules or atoms, which are created when an electron jumps from a negative to a positive ion, then leave the storage rings and hit a detector.
“We want to be able to see which reactions take place in connection with the electron transfer, even for molecules consisting of many atoms. To achieve this, we are developing a new type of detector together with German colleagues, a so-called microcalorimeter. This will enable us to measure the kinetic energy of the neutral products and thus derive their masses and identities,“ says Henning Schmidt
Theory becomes practice
The aim is that the new experimental results and the theoretical calculations together will be able to determine how efficient different reactive charge transfer processes are, in order to be able to assess how much they affect different types of cold environments exposed to ionizing radiation.
“By participating in a large international project related to the James Webb Space Telescope, we will then apply and test our new knowledge and models to contribute to new interpretations of the increasingly refined information about the universe provided by the telescope,“ says Henning Schmidt.
Last updated: October 17, 2024
Source: Communications Office