Morphing twisted nanoscale objects to tailor applications in future technologies

May 3, 2018 by Chris Melvin, University of Bath
An impression of a chiral molecule moving through various configurations as it transitions from one handedness to another. Credit: Ventsislav Valev and Joel Collins

For the first time scientists have created a way to model the interaction between light and twisted molecules, as these molecules transition from left- to right-handed versions, or vice versa. The transitional forms offer a deeper insight into material symmetries and their unexpected behaviour could lead to improved design of telecoms components.

Many , including important pharmaceuticals and valuable chemicals, exist in two "chiral" forms - they have the same chemical structure arranged in mirror images, termed left-handed and right-handed forms. This can alter their properties and is therefore important to fully understand how the compound interacts with other molecules, or light.

Typically, it has only been possible to study either the left- or right-handed chiral form but nothing in between, however ideally scientists would like to gradually morph a shape from one handedness to the other and observe how the effects of this change translate into physical properties.

Now a research team from the Department of Physics at the University of Bath, working with colleagues at University College London, Belgium and China, has created a way to do exactly that.

Their unique method involves manufacturing metallic nano-scale "" representative of 35 intermediate stages along the way of a geometric transformation, from one handedness to the other. At this nano-scale, the shape of the artificial molecule affects its optical properties, so by using twisted laser light the team studied the properties of the various stages, as the artificial molecules morphed from left to right handedness.

PhD student Joel Collins said: "We were able to follow the properties of a chiral artificial molecule, as it was morphed from left- to right-handed form, through two different routes. No-one has done this before. Surprisingly, we found that each route leads to a different behavior.

"We measured the difference in absorption of left and right circularly polarized light, known as circular-dichroism (CD). Along one route, the artificial molecules behaves as might be expected, with progressively decreasing CD, and eventually a reversal of the CD, for the mirrored structure. However, along the second route, the CD reversed several times, even before the structure changed handedness."

The research is published in the journal Advanced Optical Materials.

Dr Ventsislav Valev who led the research said: "This is actually a very elegant idea but it has only become a possibility thanks to the recent advances in nanofabrication.

"In chemistry, you can't tune the twist of a , so every scientist who studies such molecules needs to tune the wavelength of . We have demonstrated a new, complementary physical effect, where we fix the wavelength and tune the twist of the chiral artificial molecule. In many cases, our approach is more practical; for instance, when we're designing telecoms components, where the optical wavelength is pre-determined."

Explore further: Twisting laser light offers the chance to probe the nano-scale

More information: Joel T. Collins et al, Enantiomorphing Chiral Plasmonic Nanostructures: A Counterintuitive Sign Reversal of the Nonlinear Circular Dichroism, Advanced Optical Materials (2018). DOI: 10.1002/adom.201800153

Related Stories

New method to determine molecule chirality

February 20, 2018

Identifying right-handed and left-handed molecules is a crucial step for many applications in chemistry and pharmaceutics. An international research team (CELIA-CNRS/INRS/Berlin Max Born Institute/SOLEIL) has now presented ...

Chiral crabs

September 22, 2017

Sander Wezenberg, and PhD students Thomas van Leeuwen and Kaja Sitkowska, from the University of Groningen in the Netherlands, spoke to us about their work in chirality and molecular motors, and the seaside scene on the cover ...

Recommended for you

Nanoscale Lamb wave-driven motors in nonliquid environments

March 19, 2019

Light driven movement is challenging in nonliquid environments as micro-sized objects can experience strong dry adhesion to contact surfaces and resist movement. In a recent study, Jinsheng Lu and co-workers at the College ...

OSIRIS-REx reveals asteroid Bennu has big surprises

March 19, 2019

A NASA spacecraft that will return a sample of a near-Earth asteroid named Bennu to Earth in 2023 made the first-ever close-up observations of particle plumes erupting from an asteroid's surface. Bennu also revealed itself ...

The powerful meteor that no one saw (except satellites)

March 19, 2019

At precisely 11:48 am on December 18, 2018, a large space rock heading straight for Earth at a speed of 19 miles per second exploded into a vast ball of fire as it entered the atmosphere, 15.9 miles above the Bering Sea.

Revealing the rules behind virus scaffold construction

March 19, 2019

A team of researchers including Northwestern Engineering faculty has expanded the understanding of how virus shells self-assemble, an important step toward developing techniques that use viruses as vehicles to deliver targeted ...

Levitating objects with light

March 19, 2019

Researchers at Caltech have designed a way to levitate and propel objects using only light, by creating specific nanoscale patterning on the objects' surfaces.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.