Scientists Discovered a New Mechanism for Formaldehyde Formation in Space

14:47, December 27, 2021

They found that molecules in cosmic nebulae form earlier than expected

Scientists from Leiden (Netherlands), Stuttgart (Germany), and Ural Federal University have successfully developed and experimentally tested the theory that formaldehyde forms at much earlier stages in the evolution of interstellar molecular clouds, where stars originate, than previously thought. Article about their research work colleagues published in one of the world's leading scientific journals The Journal of Physical Chemistry Letters.

According to previous views, the formation of formaldehyde H2CO on the surface of space dust, covered with water ice, through the connection of carbon atoms C to water molecule H2O difficult. The contradiction was seen in the fact that the implementation of the reaction between the carbon atom and the water molecule to form formaldehyde requires a huge amount of energy, which in cosmic nebulae, at -263°C, is not enough for this purpose. Therefore, formaldehyde molecules were thought to form at later stages of the life of molecular clouds - when carbon monoxide CO in the solid state is abundantly present on cosmic dust particles.

Using the most modern methods of computational chemistry, scientists from Leiden University, the University of Stuttgart, and UrFU proposed an alternative mechanism for the reaction and thus showed that formaldehyde can be formed by the interaction of atomic carbon with water ice.

"Water in this case is represented as a cluster of amorphous ice. We call it amorphous because in molecular clouds ice is formed by the instant cooling of formed water molecules, which do not have time to form a crystal lattice. Water ice molecules, which cover submicrometer sized space dust particles, react with carbon atoms, which are frozen out of the gas phase. Thus, a complex of a water molecule and a carbon atom is formed," says Gleb Fedoseyev, a leading researcher of the Scientific Laboratory of Astrochemical Research UrFU, responsible for conducting the experiments in the research.

The water molecules, bound by hydrogen bonds, act simultaneously as donors and acceptors of protons (positive hydrogen ions), carrying out proton pseudo-transfer from the oxygen atom of the formed complex to the carbon atom.

"This coordinated proton transfer along the chain of hydrogen bonds between water molecules catalyzes the reaction, accelerating the formation of formaldehyde. Such transformations occur practically barrier-free and do not require much energy. This circumstance eliminates the contradiction between the classical notions of the reaction mechanism and the possibility of its occurrence in real space conditions," Gleb Fedoseyev notes.

As a simple carbonyl (i.e. containing -CO group) compound, formaldehyde plays a central role in the formation of complex organic compounds and is one of the sources of molecules necessary for the origin of life and its development. By proving the possibility of formaldehyde formation from atomic carbon and water ice, scientists in Europe and Russia have thus substantiated that complex organic compounds can be present in space already at the early stages of molecular cloud evolution, before CO freezing, and much earlier than the appearance of stars and planetary systems. Moreover, probably in large quantities, since nebulae contain enormous amounts of water and, therefore, formaldehyde.

"More than 150 years ago, our compatriot and outstanding chemist Aleksandr Butlerov proposed one of the first methods of abiotic synthesis of sugars. This method involved the use of formaldehyde solutions in water. Could Butlerov have imagined that all the components necessary for the reaction, then named after him, are present in the gas-dust clouds that form star systems like our Solar System, where the total mass of formaldehyde and water exceeds the mass of the Earth by orders of magnitude?" - Gleb Fedoseyev adds.

The scientists' hypothesis was verified in several experiments on the installation, reproducing the physical conditions of space. The results of the experiments were confirmed by research carried out at the Max Planck Institute for Astronomy, Europe's leading network of research organizations. In addition, according to Gleb Fedoseyev, in the future the theory will be subjected to further tests using the James Webb telescope, which was launched into space on December 25. The new telescope will replace the famous Hubble to, at a distance of 1.6 million kilometers from Earth, continue the observation of space objects, including space ices. From the images obtained from James Webb, scientists hope to obtain data on the birth of the universe, the formation of stars, to detect traces of extraterrestrial life.

Given the scientific significance of the theoretical developments and experiments conducted, the research of Gleb Fedoseyev and his colleagues was supported by state organizations supporting science in Germany, the Netherlands, and Denmark, and, on the Russian side, by the Russian Ministry of Science and Higher Education. Note that the Scientific Laboratory for Astrochemical Research at UrFU was commissioned by the Ministry to create a facility for modeling the conditions of space, and the team of the laboratory is being expanded in this context.

Reference

Previously, an international group of astrochemists, in which Russia was represented by Gleb Fedoseev, found that glycine (a simple amino acid and a key element of living systems) can be formed in the harsh conditions of deep space without ultraviolet radiation and cosmic rays. The study showed that glycine and, most likely, other amino acids form in dense interstellar clouds long before they become new stars and planets.