Monday 24 July 2023

Unveiling the quantum dance: Experiments reveal nexus of vibrational and electronic dynamics

 



Nearly a century ago, physicists Max Born and J. Robert Oppenheimer developed an assumption regarding how quantum mechanics plays out in molecules, which are comprised of intricate systems of nuclei and electrons. The Born-Oppenheimer approximation assumes that the motion of nuclei and electrons in a molecule are independent of each other and can be treated separately.

This model works the vast majority of the time, but scientists are testing its limits. Recently, a team of scientists demonstrated the breakdown of this assumption on very fast time scales, revealing a close relationship between the dynamics of nuclei and electrons. The discovery could influence the design of molecules useful for solar energy conversion, energy production, quantum information science and more.

The team, including scientists from the U.S. Department of Energy's (DOE) Argonne National Laboratory, Northwestern University, North Carolina State University and University of Washington, recently published their discovery in two related papers in Nature and Angewandte Chemie International Edition.

"Our work reveals the interplay between the dynamics of electron spin and the vibrational dynamics of the nuclei in molecules on superfast time scales," said Shahnawaz Rafiq, a research associate at Northwestern University and first author on the Nature paper. "These properties can't be treated independently—they mix together and affect electronic dynamics in complex ways."

A phenomenon called the spin-vibronic effect occurs when changes in the motion of the nuclei within a molecule affect the motion of its electrons. When nuclei vibrate within a molecule—either due to their intrinsic energy or due to external stimuli, such as light—these vibrations can affect the motion of their electrons, which can in turn change the molecule's spin, a quantum mechanical property related to magnetism.

In a process called inter-system crossing, an excited molecule or atom changes its electronic state by flipping its electron spin orientation. Inter-system crossing plays an important role in many chemical processes, including those in photovoltaic devices, photocatalysis and even bioluminescent animals. For this crossing to be possible, it requires specific conditions and energy differences between the electronic states involved.


at

No comments:

Post a Comment

Subscribe to: Post Comments (Atom)

Experimental quantum imaging distillation with undetected light

  It is possible to image an object with an induced coherence effect by making use of photon pairs to gain information on the item of intere...