 |
|
Radicals Shake Up Molecules in a Tug o' War
July 07, 2008Until now, it was commonly thought that colliding molecules get the shakes as the result of energy transfer solely from the smashing of the molecules, but some new research adds a second means by which colliding molecules become vibrationally excited--it is being called the "Tug o' War Mechanism."
The new experiment, transforming the textbook story, was performed in the lab of Richard Zare, chair of the Department of Chemistry at Stanford University. This work on energy transferring, or inelastic, collisions is featured in the July 3, 2008 issue of the journal Nature.
"How energy transfer occurs in molecular collisions is a topic of deep interest to chemists, for energy transfer is often the precursor to chemical transformations," Zare said. "This is the reason why I regard finding a new mechanism for energizing molecules through collisions to be of such potential importance."
"The work by Zare and his colleagues shows an interesting and unexpected result," shared Charles Pibel, director of the Physical Chemistry Program at the National Science Foundation (NSF). "The conventional wisdom had been that most collisions between molecules excite vibrational motion through a hard impact, like a piano's hammer striking a string."
But instead of molecules impacting and deflecting backwards, the Tug o' War Mechanism stretches the molecule and then releases it, starting the molecule rattling. The effect is "more like a violinist, plucking a string, pizzicato." In the collisions studied by the Zare group, a lone hydrogen atom tugs on one end of a deuterium molecule and lets go, exciting the molecular deuterium into vibration.
More generally, the Tug o' War Mechanism comes into play when a certain type of unstable species, a free radical, looms down a path for collision with another molecule. Because free radicals lack a properly balanced shell of electrons, they are more susceptible to the mechanism than other types of atoms or molecules.
Sometimes a collision between a free radical and another molecule rips apart chemical bonds and atoms are exchanged amongst the colliding partners--that is, a chemical reaction takes place. However, other times when free radicals approach other molecules, this Tug o' War Mechanism stretches the molecule without breaking the bonds.
In this way, free radicals act like renegades attempting to steal atoms from their parent molecule by tugging them away. But if a collision is not at the right angle, the radical might not be able to break the bonds of the molecule. It releases its hold on the nearest atom, or atoms, and then departs. The frustrated, or unsuccessful, chemical reaction nevertheless imparts some energy on the victim of the free radical attack. It is this energy that sets the molecule off dancing with a new vibrational pattern.
The research, funded by NSF, was led by Noah T. Goldberg at Stanford University and Stuart J. Greaves at the University of Bristol, U.K., and included Zare, Jianyang Zhang and Daniel J. Miller, all from Stanford University, and Eckart Wrede from the University of Durham, U.K.
The National Science Foundation (NSF)
"The work by Zare and his colleagues shows an interesting and unexpected result," shared Charles Pibel, director of the Physical Chemistry Program at the National Science Foundation (NSF). "The conventional wisdom had been that most collisions between molecules excite vibrational motion through a hard impact, like a piano's hammer striking a string."
But instead of molecules impacting and deflecting backwards, the Tug o' War Mechanism stretches the molecule and then releases it, starting the molecule rattling. The effect is "more like a violinist, plucking a string, pizzicato." In the collisions studied by the Zare group, a lone hydrogen atom tugs on one end of a deuterium molecule and lets go, exciting the molecular deuterium into vibration.
More generally, the Tug o' War Mechanism comes into play when a certain type of unstable species, a free radical, looms down a path for collision with another molecule. Because free radicals lack a properly balanced shell of electrons, they are more susceptible to the mechanism than other types of atoms or molecules.
Sometimes a collision between a free radical and another molecule rips apart chemical bonds and atoms are exchanged amongst the colliding partners--that is, a chemical reaction takes place. However, other times when free radicals approach other molecules, this Tug o' War Mechanism stretches the molecule without breaking the bonds.
In this way, free radicals act like renegades attempting to steal atoms from their parent molecule by tugging them away. But if a collision is not at the right angle, the radical might not be able to break the bonds of the molecule. It releases its hold on the nearest atom, or atoms, and then departs. The frustrated, or unsuccessful, chemical reaction nevertheless imparts some energy on the victim of the free radical attack. It is this energy that sets the molecule off dancing with a new vibrational pattern.
The research, funded by NSF, was led by Noah T. Goldberg at Stanford University and Stuart J. Greaves at the University of Bristol, U.K., and included Zare, Jianyang Zhang and Daniel J. Miller, all from Stanford University, and Eckart Wrede from the University of Durham, U.K.
The National Science Foundation (NSF)
Energy Transfer Current Events and Energy Transfer News RSSLANL Roadrunner models nonlinear physics of high-power lasers
For years scientists have struggled with the difficult physics of inertial confinement fusion. This is the attempt to compress a target capsule containing isotopes of hydrogen with high-powered lasers to high enough pressure and temperature to initiate fusion burn.
Single-stranded DNA-binding protein is dynamic, critical to DNA repair
Researchers report that a single-stranded DNA-binding protein (SSB), once thought to be a static player among the many molecules that interact with DNA, actually moves back and forth along single-stranded DNA, gradually allowing other proteins to repair, recombine or replicate the strands.
Toward better solar cells: Chemists gain control of light-harvesting paths
University of Florida chemists have pioneered a method to tease out promising molecular structures for capturing energy, a step that could speed the development of more efficient, cheaper solar cells.
Scientists discover surprise in Earth's upper atmosphere
UCLA atmospheric scientists have discovered a previously unknown basic mode of energy transfer from the solar wind to the Earth's magnetosphere. The research, federally funded by the National Science Foundation, could improve the safety and reliability of spacecraft that operate in the upper atmosphere.
Live recordings of cell communication
A new advanced method for nano-scale imaging of vesicle-fusion - vesicles are biological nano-sized containers - could add to our understanding of diseases of the nervous system and viral infections.
Researchers observe single protein dimers wavering between two symmetrically opposed structures
Researchers at The Scripps Research Institute, the University of California, San Diego, and Ohio State University have used a very sensitive fluorescence technique to find that a bacterial protein thought to exist in one "natural" three-dimensional structure (shape), can actually twist itself into a second form, depending on the protein's chemical environment.
Scientists create first comprehensive computer model of sunspots
In a breakthrough that will help scientists unlock mysteries of the sun and its impacts on Earth, scientists have created the first-ever comprehensive computer model of sunspots.
Orientation of antenna protein in photosynthetic bacteria described
Researchers at Washington University in St. Louis have figured out the orientation of a protein in the antenna complex to its neighboring membrane in a photosynthetic bacterium, a key find in the process of energy transfer in photosynthesis.
Scripps research scientists 'watch' as individual alpha-synuclein proteins change shape
In an Early Edition publication of The Proceedings of the National Academy of Sciences (PNAS) this week, the researchers demonstrate the "alpha-synuclein dance" - the switching back and forth of the protein between a bent helix and an extended helix as the surface that it is binding to changes.
Walking forum report shows need to expand physical activity in schools
With childhood obesity expanding to epidemic proportions in the United States, educators, researchers and health practitioners are actively seeking to identify effective means of addressing this public-health crisis.
More Energy Transfer Current Events and Energy Transfer News Articles
 |
Energy Makes Things Happen (Let's-Read-and-Find-Out Science 2) by Kimberly Brubaker Bradley (Author), Paul Meisel (Illustrator) Did you know that energy comes from the food you eat? From the sun and wind? From fuel and heat? You get energy every time you eat. You transfer energy to other things every time you play baseball. In this book, you can find out all the ways you and everyone on earth need energy to make things happen. |
|
Journal of Energy Heat and Mass Transfer by Reg Ctr Ener Heat & Mass Trans | |
|
Energy in Action: The Transfer of Energy | |
|
ENERGY SUSPENSION 31107G Transfer Case Mount Bushing by ENERGY SUSPENSION | |
 |
SciEd Accent Science: Investigating Energy Transfer by Science First Investigating Energy Transfer |
 |
272677 Desiccant Energy Transfer Wheel by Honeywell 272677 Desiccant Energy Transfer Wheel |
 |
Energy - 8x8 Iron On Heat Transfer For White Material by 3dRose LLC Energy Iron on Heat Transfer is printed on a 8 by 8 inch commercial quality high resolution heat transfer paper, available for white and light material applications only. Heat transfer is shipped with the home use instructions for use with a home iron. |
|
Energy Transfer 10 tracks, 1980 | |
 |
Energy Transfer The Heaters (Primary Contributor) |
 |
Easton Stealth Composite BCN14 Senior League Bat - ( sz. 27, -9 OZ 2 5/8" ) by Easton CNT Carbon Nanotube technology featured in the Easton Stealth BCN14 Senior League Bat strengthens composite structures, optimizing designs for maximum performance. Extended Plex design lengthens the sweet spot by increasing the barrel flex towards the contour and end of the bat to provide maximum performance along the entire length of the barrel. Opti-Flex CNT composite handle technology provides maximum handle flex two times greater than aluminum. ConneXion technology acts like a hinge to provide the most efficient energy transfer from handle to barrel for maximum bat head "whip" for a quicker bat and more power through the hitting zone. IMX - Integrated MatriX technology optimizes the relationship between materials, design technologies and manufacturing process. 2 5/8" extended barrel... |
| © 2009 BrightSurf.com |