Periodic Reporting for period 2 - PICOFORCE (Pico-Photonic Forces at the Atomic Scale)
Période du rapport: 2022-07-01 au 2023-12-31
The key aim of this project is to understand and utilise optically-produced forces on the atomic scale, in order to devise future nano-mechanisms and nano-machines. Key goals are to move individual metal atoms by light, twist and compress and flip individual molecules on demand, and provide a step-change in the comprehension of how ions, solvent, molecules and electrons interact at interfaces, which is critical in catalysis, molecular electronics, quantum control, electrochemistry, and nano-assembly. These processes underpin synthesis of materials across society, and their use and exploitation.
This research exploits our new capability to confine visible and infrared light to the atomic scale. This compression of the photons into a small volume seems to radically change the forces that the light can produce. We are exploring how to understand and exploit these forces.
This research exploits our new capability to confine visible and infrared light to the atomic scale. This compression of the photons into a small volume seems to radically change the forces that the light can produce. We are exploring how to understand and exploit these forces.
A very large range of experiments to better understand and control the confinement of light on the nm and sub-nm scales has been undertaken. Our approach to making scalable precision nano-architectures that confine light has been using bottom-up self-assembly of nanostructures, and this has gained international notoriety as a highly-effective route that avoids expensive complex fabrication. We routinely now make nm-gap structures that confine light (daily), and explore their properties. This underpins all our research.
We have published >50 high impact papers since the start of the project, so that we can only highlight a few of the key results here.
(note that the publications upload page is not working [email with ERCEA Scientific Follow-Up Team 7/7/23] and thus a pdf of the list has been provided to the project officers).
Most significant for the project is our quantification of optical-induced forces on molecules inside metallic nanogaps, which shows they are a thousand times larger than expected from classical theory. This arises from the interaction between light, polarisable molecules, and metallic surfaces. We have produced an initial model that explains this, and theory group around the world are struggling to develop this. The key issue is to combine quantum and classical theories, which is currently impossible. However our experiments are unambiguous, rich and extensive, and constrain many explanations. We even now develop cases where room light can move around the metal atoms from these forces, or a single dye molecule can resculpt metal contacts when illuminated.
A second significant advance has been to show that mid-infrared light can also be confined in our nanogap cavities, which allows new phenomena to be demonstrated. In particular we invented (and patented) a new way to use this to detect midinfrared light by ‘upconverting’ it into visible light inside these nanogaps. We are now trying to understand the key mechanisms which involve interactions with the confined molecules and the midinfrared and visible light, and also make a demonstrator.
A third advance has been to show that illuminating molecules inside these nanogaps can change their bonds, weakening their strength progressively as the light becomes more intense. We have also developed a theory based on ‘optomechanics’ that explains this, and see it as changes in the vibrational spectrum for even weak light intensities.
Finally we also developed a system combining carbon nanotubes and thermoresponsive polymers to make microscale ‘jellyfish’ that flap their tentacles when illuminated by light, and we are continuing to develop these actuators.
We have published >50 high impact papers since the start of the project, so that we can only highlight a few of the key results here.
(note that the publications upload page is not working [email with ERCEA Scientific Follow-Up Team 7/7/23] and thus a pdf of the list has been provided to the project officers).
Most significant for the project is our quantification of optical-induced forces on molecules inside metallic nanogaps, which shows they are a thousand times larger than expected from classical theory. This arises from the interaction between light, polarisable molecules, and metallic surfaces. We have produced an initial model that explains this, and theory group around the world are struggling to develop this. The key issue is to combine quantum and classical theories, which is currently impossible. However our experiments are unambiguous, rich and extensive, and constrain many explanations. We even now develop cases where room light can move around the metal atoms from these forces, or a single dye molecule can resculpt metal contacts when illuminated.
A second significant advance has been to show that mid-infrared light can also be confined in our nanogap cavities, which allows new phenomena to be demonstrated. In particular we invented (and patented) a new way to use this to detect midinfrared light by ‘upconverting’ it into visible light inside these nanogaps. We are now trying to understand the key mechanisms which involve interactions with the confined molecules and the midinfrared and visible light, and also make a demonstrator.
A third advance has been to show that illuminating molecules inside these nanogaps can change their bonds, weakening their strength progressively as the light becomes more intense. We have also developed a theory based on ‘optomechanics’ that explains this, and see it as changes in the vibrational spectrum for even weak light intensities.
Finally we also developed a system combining carbon nanotubes and thermoresponsive polymers to make microscale ‘jellyfish’ that flap their tentacles when illuminated by light, and we are continuing to develop these actuators.
Many of the results are far beyond what we had expected on commencing this project, and all the results above and detailed in the other sections are beyond the state of the art.
Our aim in the rest of the project is to be able to create optically-powered pumps, valves, and walking/flapping nanomachines, and to develop sophisticated ways to fully control the movement of single metal atoms in nanogaps by light.
So far the progress can be summarised:
Goal A1: Developing optical tools: already exceeded, further work in progress
Goal A2: Understanding picocavity forces: already exceeded, further work in progress
Goal B1: Picocavities on demand: started, further work in progress
Goal B2: Light actuation at the atomic scale: started, further work in progress
Goal C1: Optical polarizability forces on molecules: demonstrated
Goal C2: Optical forces on ions in molecular monolayers: initial work now being developed
Goal D1: Molecular flexing by light: exceeded, further work to exploit
Goal D2: Opto-mechanical back-action forces: exceeded and completed
Our aim in the rest of the project is to be able to create optically-powered pumps, valves, and walking/flapping nanomachines, and to develop sophisticated ways to fully control the movement of single metal atoms in nanogaps by light.
So far the progress can be summarised:
Goal A1: Developing optical tools: already exceeded, further work in progress
Goal A2: Understanding picocavity forces: already exceeded, further work in progress
Goal B1: Picocavities on demand: started, further work in progress
Goal B2: Light actuation at the atomic scale: started, further work in progress
Goal C1: Optical polarizability forces on molecules: demonstrated
Goal C2: Optical forces on ions in molecular monolayers: initial work now being developed
Goal D1: Molecular flexing by light: exceeded, further work to exploit
Goal D2: Opto-mechanical back-action forces: exceeded and completed