Research Highlights

Magic Light

Zelevinsky and her apparatus Credit: Jeff Fal

"In the right light, in the right time, everything is extraordinary," according to photographer Aaron Rose. He could have just as easily been describing precision optical spectroscopy experiments recently conducted by Research Associates Tanya Zelevinsky and Tetsuya Ido, Graduate Students Martin Boyd and Andrew Ludlow, Fellow Jun Ye and collaborators from Poland's Instytut Fizyki and NIST's Atomic Physics Division. Read more »

Wanted: Gravitational Waves

The Laser Interferometer Space Antenna (LISA) Credit: JPL

When will the Laser Interferometer Space Antenna (LISA) fly? Fellows Jim Faller and Peter Bender first proposed the basic concept behind LISA more than 25 years ago. The joint European Space Agency/NASA mission first scheduled a possible launch in 2012. The date has now slipped to 2017, with additional delays possible. Both agencies are grappling with limited budgets and conflicting priorities. In the United States, plans for a future manned spaceflight to Mars are competing for funding with basic science-oriented space programs like LISA. Read more »

Trapped!

A solvent is something that dissolves or disperses something else. It's the water in salt water, the alcohol in cough syrup, the lactates or ethers in inks. For many of us, solvents are the background music of the chemistry taking place all around us. But this isn't how Fellow Carl Lineberger and his colleagues in chemical physics think about solvents. Lineberger, Former Research Associate Vladimir Dribinski, Graduate Students Jack Barbera and Josh Martin, and student visitor Annette Svendsen see them as key players in some chemical reactions, right down to the level of quantum mechanical interactions. Read more »

Gold Fever

Temperature gradient around a gold bead. Credit: Tom Perkins group

Life can be challenging on the biophysics research frontier. Consider gold nanoparticles as a research tool, for example. Gold is ductile and malleable as well as being a good conductor of heat and electricity. Its unique chemistry allows proteins and DNA to be easily attached to these nanoparticles. Physicists have been investigating gold nanoparticles in optical-trapping experiments because they enhance trapping efficiency and potentially increase detection sensitivity. Read more »

Constant Vigilance

The fine structure constant is getting a lot of attention these days. Known as α, it is the "coupling constant," or measure of the strength of the electromagnetic force that governs how electrons, muons, and light interact. What's intriguing is that new models for the basic structure of matter predict that α may have changed over vast spans of cosmic time, with the largest variations occurring in the early universe. However, the Standard Model says a has always been the same. Read more »

Molecular Motion Pictures

If you want to understand how chemical reactions happen, the ability to monitor dynamic positions of atoms in a molecule is critical. There's a well-known laser technique known as coherent Raman spectroscopy that uses a scattering laser pulse to set atoms vibrating and then measures the color shift of reflected light to detect vibration patterns. This technique has been used as a molecular fingerprinting device for simple motions of a molecule. However, if you want to probe rapid or complex three-dimensional atomic motion in molecules, current experimental techniques, such as electron or X-ray diffraction, are very limited in time or space resolution. Read more »

Bull's Eye!

"Chemistry is a highly improbable science," says Graduate Student Mike Deskevich, who adds "It's good for life on Earth that things are so unreactive." For instance, if chemical reactions happened easily and often, oxygen in the air would cause clothing and other flammable materials to burst into flame. In addition to making life difficult, high probability chemistry would render theoretical chemical physics much less interesting. As it is, theorists spend months determining the particular molecular shapes, vibrations, and energy states that make the simplest chemical reactions possible. Read more »

Molecular Fingerprinting

Science sleuths have a new and powerful method for identifying (and investigating) atoms and molecules, thanks to Graduate Student Mike Thorpe, Research Associate Kevin Moll, Senior Research Associate Jason Jones, Undergraduate Student Assistant Ben Safdi, and Fellow Jun Ye. The new method allows them to study molecular vibrations, rotations, and collisions as well as temperature changes and chemical reactions. The technique can also detect trace amounts of chemicals with exquisite sensitivity because it can precisely identify their characteristic patterns of laser light absorption, or molecular fingerprints. What's so special about this method is that its broad spectral bandwidth makes it possible to detect millions of parallel light channels simultaneously in real time. Read more »

Flare Up!

Gamma-ray bursts signal the birth of a new black hole, whether it's created during the collapse of a massive star or via a merger between two compact objects such as neutron stars. Astrophysicists have determined that long gamma-ray bursts are associated with collapsing stars and short bursts are associated with binary mergers. In both cases, however, black-hole accretion powers the burst. Recently the Swift X-ray Telescope revealed another common feature: erratic X-ray flares in their afterglows. Swift has detected flare-ups in about half of the gamma-ray bursts it has observed so far. Read more »

Heme Motions

Our lives depend on heme. As part of hemoglobin, it carries oxygen to our tissues. As part of cytochrome c, it helps transform the energy in food into the energy-rich molecule ATP (adenosine triphosphate) that powers biochemical reactions that keep us alive and moving. As part of cytochrome P450, it helps break down toxic chemicals in our bodies. Read more »