Light-driven nanoscale plasmonic motors

When Sir William Crookes developed a four-vaned radiometer, also known as the light-mill, in 1873, it was believed that this device confirmed the existence of linear momentum carried by photons¹, as predicted by Maxwell's equations. Although Reynolds later proved that the torque on the radiometer was caused by thermal transpiration², researchers continued to search for ways to take advantage of the momentum of photons and to use it for generating rotational forces. The ability to provide rotational force at the nanoscale could open up a range of applications in physics, biology and chemistry, including DNA unfolding and sequencing^{3, 4, 5, 6} and nanoelectromechanical systems^7, 8, 9,10. Here, we demonstrate a nanoscale plasmonic structure that can, when illuminated with linearly polarized light, generate a rotational force that is capable of rotating a silica microdisk that is 4,000 times larger in volume. Furthermore, we can control the rotation velocity and direction by varying the wavelength of the incident light to excite different plasmonic modes.

Nature Nanotechnology

 

5,

 

570–573

 

(2010)

 

doi:10.1038/nnano.2010.12

Quantum computing

The next big thing in computing is very small. Professor Michelle Simmons (UNSW) explains quantum computing.

27 January 2011 - Shunting path formation in thin film structures

Krisztian will present the following paper:

Shunting path formation in thin film structures

M. Nardone, M. Simon,a and V. G. Karpov
APPLIED PHYSICS LETTERS 96, 163501 2010

We present a model for shunt formation in thin films containing small volume fractions of conductive components, below the critical volume fraction of percolation theory. We show that in this regime shunting is due to almost rectilinear conductive paths, which is beyond the percolation theory framework. The criteria of rectilinear paths shunting versus the percolation cluster scenario are established. The time and temperature dependence of shunting statistics is predicted with possible applications in phase change memory and thin oxides.

Carbon nanotubes spin a yarn

Multifunctional applications of textiles have been limited by the inability to spin important materials into yarns. Generically applicable methods are demonstrated for producing weavable yarns comprising up to 95 weight percent of otherwise unspinnable particulate or nanofiber powders that remain highly functional. Scrolled 50-nanometer-thick carbon nanotube sheets confine these powders in the galleries of irregular scroll sacks whose observed complex structures are related to twist-dependent extension of Archimedean spirals, Fermat spirals, or spiral pairs into scrolls. The strength and electronic connectivity of a small weight fraction of scrolled carbon nanotube sheet enables yarn weaving, sewing, knotting, braiding, and charge collection. This technology is used to make yarns of superconductors, lithium-ion battery materials, graphene ribbons, catalytic nanofibers for fuel cells, and titanium dioxide for photocatalysis.

Article info:

Biscrolling Nanotube Sheets and Functional Guests into Yarns

Science 7 January 2011: 
Vol. 331 no. 6013 pp. 51-55 
DOI: 10.1126/science.1195912


http://www.sciencemag.org/content/331/6013/51.full

Star Wars is real!

Holography is a technique that is used to display objects or scenes in three dimensions. Such three-dimensional (3D) images, or holograms, can be seen with the unassisted eye and are very similar to how humans see the actual environment surrounding them. The concept of 3D telepresence, a real-time dynamic hologram depicting a scene occurring in a different location, has attracted considerable public interest since it was depicted in the original Star Wars film in 1977. However, the lack of sufficient computational power to produce realistic computer-generated holograms¹ and the absence of large-area and dynamically updatable holographic recording media² have prevented realization of the concept. Here we use a holographic stereographic technique³ and a photorefractive polymer material as the recording medium⁴ to demonstrate a holographic display that can refresh images every two seconds. A 50 Hz nanosecond pulsed laser is used to write the holographic pixels⁵. Multicoloured holographic 3D images are produced by using angular multiplexing, and the full parallax display employs spatial multiplexing. 3D telepresence is demonstrated by taking multiple images from one location and transmitting the information via Ethernet to another location where the hologram is printed with the quasi-real-time dynamic 3D display. Further improvements could bring applications in telemedicine, prototyping, advertising, updatable 3D maps and entertainment.

Article info:

Holographic three-dimensional telepresence using large-area photorefractive polymer

Nature

 

468,

 

80–83

 

(04 November 2010)

 

doi:10.1038/nature09521

http://www.nature.com/nature/journal/v468/n7320/full/nature09521.html

Welcome!

Welcome to the University of Exeter Functional Material Reading Group Blog!