Stories tagged UCLA

Sep
18
2007

Polymer based lasers: Sarah Tolbert and Benjamin J. Schwartz, UCLA professors of chemistry and California NanoSystems Institute members. Credit: Reed Hutchinson/UCLA
Polymer based lasers: Sarah Tolbert and Benjamin J. Schwartz, UCLA professors of chemistry and California NanoSystems Institute members. Credit: Reed Hutchinson/UCLA
Products with LED-type displays, like cell phones, laptops and PDAs will soon be brighter, cheaper, and use less electricity.
Benjamin J. Schwartz discovered in the 1990s that lasers could be made out of randomly oriented semiconducting polymer chains. Now he and Sarah Tolbert have figured a way to get the spaghetti like polymer strands to straighten out so they can emit polarized laser light toward a precise target. The trick was to force the polymer chains into tiny, nanometer-sized holes in a piece of glass.

"What we do is take tiny, nanometer-sized holes in a piece of glass and force the polymer chains into the holes. The holes are so small that the spaghetti chains have no space to coil up. They have to lie straight, and all the chains end up pointing in the same direction." said Tolbert.

Laser light produced without mirrors

In most lasers, confining the light is typically done with external mirrors. In combination, the alignment of the polymer chains and the confinement of the light make it 20 times easier for the new materials to lase. The glass host matrix with the aligned nanoscale pores is also inexpensive to produce.

Brighter, cheaper, and using fewer batteries are traits of a winner in todays marketplace.

Source: UCLA News.

May
20
2007

Nanotech sponges can absorb hydrogen, carbon dioxide, or methane.

COF-108: Credit: José L. Mendoza-Cortés
COF-108: Credit: José L. Mendoza-Cortés
Omar Yaghi was named one of the "Brilliant 10" by Popular Science magazine last fall, describing him as a "hydrogen nano-architect". Like an architect, Yaghi links together well-defined molecules like building blocks to create porous crystalline structures. Referred to as metal-organic frameworks, or MOFs, these crystal sponges have nanosized openings which can be customized to soak up only molecules of a particular size (like hydrogen or methane). MOFs could lead to the first workable fuel tanks for a hydrogen cars, or laptops and cell phones.

New material sets record for most surface area per gram.

Yaghi's newest material, called covalent organic frameworks, or COFs "(pronounced "coffs") are crystalline porous organic networks. A member of this series, COF-108, has the lowest density reported of any crystalline material. One gram of COF-108, has a surface area equal to 30 tennis courts. Yaghi specifically cited COFs as a possible storage medium for carbon dioxide capture and sequestration systems.

Learn more about Omar Yaghis and his research: