Use of attosecond laser technology in chemistry

The attosecond is the trillionth part of a second, and using this type of technology, researchers attached to the Autonomous University of Madrid in the area of ​​nanoscience and the Polytechnic Institute of Zurich, have been able to observe for the first time the correlated movement that exists between the nucleus and the electrons existing in a hydrogen molecule with the use of an attosecond laser.

This has been possible with the combination of two existing techniques, which allowed achieving a different result in the opinion of Carlos Hernández, researcher of the Laser and Photonics Applications group at the University of Salamanca.

This new technique is composed by the generation of ultrashort pulses, with attosecond duration, starting from infrared lasers, which is combined with the generation of high-frequency radiation with circular polarization, which allowed to unite two worlds that until now were different.

That is why, with the use of this novel technique, it was possible to observe for the first time the correlated movement of nuclei and electrons in a hydrogen molecule, giving the possibility of manipulating the properties of any chemical bond.

Attosecond laser and chemical reactions, nuclei, and electrons

For chemical reactions to occur, it is necessary that the breakage and subsequent formation of bonds between the atomic nuclei present in a molecule occurs, this gives rise to the formation of molecules different from the original ones.

This process occurs as a result of the movement of electrons, which with the negative charge they possess are capable of shielding the repulsion existing between the nuclei of positive electric charge.

It should be noted that the lightest nucleus that exists is the hydrogen atom (proton p +), which is approximately 1,800 times heavier than an electron, but when a molecule can absorb energy provided by an external source, such as, the light, the nuclei are able to move almost as fast as the electrons, according to how the energy has been distributed among them.

Scheme of pumping of the probe with the attosecond laser

For Alicia Palacios co-author of the investigation, in order to determine that the correlation of movement, it was necessary to bombard several attosecond ultraviolet pulses, these were synchronized with a pulse of femtosecond infrared light, and in addition, there was a variation in the delay between the two types of pulses, requiring an accuracy of only a few tens of attoseconds.

With this pulse sequence, it was possible to produce ionization and the dissociation of the molecule, which resulted in the emission of a proton, an electron, and a hydrogen atom. This proton and electron arrest combined with the temporal delays and coupled with intricate mechano-quantum calculations was what made it possible to visualize the movement of these two particles in the molecule.

Knowing that some systems can respond differently to the polarization of light, this gives the possibility to study them and to perform a better characterization of them, which provides a better way to interact with the subject.

This type of research promotes a way of entry to the manipulation of the properties that have the chemical bonds, being able to act in an indistinct way on nuclei or electrons. In addition, it may have repercussions in the pharmaceutical field and for study in other areas.