Capturing negative ions in the interstellar space

How are negatively charged molecules created in the interstellar environment?

The interstellar cloud is the birthplace of new stars, but it also plays an important role in the origin of life in the universe through the area of ​​dust and gas where compounds are formed. The molecular system, a research group led by Roland Wester, an ERC award winner at the Institute of Ion Physics, and Applied Physics at the University of Insbrook, has set the task of better understanding the development of basic molecules in space. ..

“Simply put, our ion traps allow us to recreate the state of the universe in our lab,” Roland Wester explains. “This device allows us to study the formation of compounds in detail.” Scientists working with Roland Wester explain how negatively charged molecules are formed in space. I found.

Roland Wester and Malcolm Simpson

Physicists Roland Wester (left) and Malcolm Simpson (right) show how dipole bound states form negative ions in the interstellar cloud. Credits: Bryan Goff from Unsplash / AGWester

Ideas built on a theoretical basis

Prior to the discovery of the first negatively charged carbon molecules in the universe in 2006, it was assumed that the interstellar cloud contained only positively charged ions. Since then, how negatively charged ions are formed has been an open question. Franco A. Janturco, an Italian theorist who has worked as a scientist at the University of Insbrook for eight years, developed a theoretical framework that could provide possible explanations a few years ago. The presence of weakly bound states, the so-called dipole bound states, should enhance the attachment of free electrons to linear molecules. Such molecules have a permanent dipole moment that enhances the interaction and increases the free electron capture rate at a relatively long distance from the neutral nucleus.

Observation of dipole bound state in the laboratory

In their experiments, Insbrook physicists created molecules consisting of three carbon atoms and one nitrogen atom, ionized them, and irradiated them with laser light in a cryogenic ion trap. They continuously changed the frequency of light until the energy was large enough to emit electrons from the molecule.

Albert Einstein explained this so-called photoelectric effect 100 years ago. A detailed analysis of the measured data by Malcolm Simpson, an early PhD researcher, the atoms, lights, and molecules of the University of Insbrook finally shed light on this difficult-to-observe phenomenon. Comparing the data with the theoretical model finally provided clear evidence of the existence of a dipole bound state.

“In our interpretation, these dipole bound states open a kind of door for binding free electrons to the numerator and therefore contribute to the generation of negative ions in space,” Roland Wester said. Says. “Without this intermediate step, it is highly unlikely that an electron will actually bind to the molecule.”

Reference: “Effect of supercritical electric dipole moment on photo-elimination of C”3NSMalcolm Simpson, Markus Nötzold, Tim Michaelsen, Robert Wild, Franco A. Gianturco, Roland Wester, July 19, 2021 Physical review letter..
DOI: 10.1103 / PhysRevLett.127.043001

This work was supported by the Austrian Scientific Foundation FWF. The fund also funds the University of Insbrook PhD program Atoms, Light and Molecules (ALM). Capturing negative ions in the interstellar space

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