Scientists from Northwestern University and the University of Wisconsin-Madison have discovered that centrosymmetric crystals can absorb chiral light asymmetrically, challenging long-held beliefs about crystal behavior. Previously, it was thought that only non-centrosymmetric materials could exhibit chiral properties. The study, published in the journal Science on June 12, reveals that a specific centrosymmetric crystal absorbed circularly polarized light differently depending on its direction.
“This discovery is surprising to many in the scientific community whom, for a long time, thought this principle was impossible,” said Roel Tempelaar from Northwestern University. Tempelaar co-led the study with Kenneth Poeppelmeier and Randall Goldsmith.
Chirality is a fundamental concept where an object and its mirror image cannot be superimposed. It plays a crucial role in molecular interactions affecting food flavors, medicine effectiveness, and biological systems. Tempelaar explained that molecules often come in two forms: “They have a ‘right-handed’ form and a ‘left-handed’ form.”
The research team predicted that a centrosymmetrical crystal made from lithium, cobalt, and selenium oxide could absorb light in a chiral manner. Despite traditional expectations, their findings showed otherwise. “To our knowledge, no centrosymmetrical crystal has been reported to do this,” Tempelaar stated.
The study was supported by the Center for Molecular Quantum Transduction with funding from the U.S. Department of Energy.