One Molecule at a Time by Bob Allen, Pacific Northwest National Laboratory Imagine the view from a blimp hovering over a crowded football stadium. The thousands of fans are blurred into a homogeneous surface surrounding the field. The observer in the blimp can accurately report on the movement of the Wave, but is at a loss to say who is participating in it, who is taking a nap, who is looking for the peanut guy.
Chemists have similar problems observing individual molecules in reactions.
In extremely complex chemical environments, the fate of an individual molecule becomes critical to understanding the chain of events. However, the intermediate steps in reactions between individual molecules have, before now, been largely invisible. Ed Yeung, a chemist at Ames Laboratory, has developed a technique to form images of individual molecules in liquid solution. Yeung and Xiao Hong Xu, a postdoctoral fellow, have tracked the motion and decomposition of rhodamine in water. They also tracked the movement of individual DNA molecules in water by tagging the DNA with rhodamine.