Scientists at Cornell University have developed a chiral thin film through rotational stacking of graphene sheets, the first such exploration of chirality at the nano scale. This material may be of interest in the fields of polarization optics, stereochemistry, optoelectronics and spintronics.
For the experiment,the researchers grew graphene sheets on copper, then cut them into multiple sheets. Those sheets were then stacked, with each sheet rotated slightly before being placed on the one below it. The rotation went clockwise on one stack and counter-clockwise on the other to form right-handed and left-handed stacks. Circularly polarized light alternating left-handed and right-handed beams were shone onto the stacks, and circular dichroism (or CD, the differential absorption of left- and right-handed light), was measured.
Chirality is a fundamental concept in a number of scientific disciplines, including medicine. It refers to a state in which two materials or objects are non-superimposable mirror images of each other, similar to hands, that are distinctly "left-handed" and "right-handed". The scientists say that this discovery and its confirmation may have a lot of implications in both pure and applied science, for example in sensing biomolecules, and to induce and control asymmetric catalysis, among others. It may also open new research directions for other 2D materials.