Stanford researchers find a quicker, cheaper way to sor...( Whether it's the summer grass tha...)

Whether it's the summer grass that tickles your feet or the red Bordeaux smacking on your palette, nearly every part of the world around you carries special chemical markers. These markers, called isotopes, can tell scientists where the molecules that compose a substance are from, where they traveled, and what happened to them along the way. But doing these analyses has been complex and costly. Now, Stanford chemists have developed a new method to make isotopic analysis easier and less expensive.

"It's all done with smoke and mirrors," said chemist Richard Zare, giving a very literal description of the new method. The device he and his collaborators have created burns chemical samples into a gas, which then flows through a laser beam that is bouncing back and forth off a set of mirrors inside a special container.

The atoms of a particular element all have the same number of protons in their core, but may have differing numbers of neutrons. Carbon, for example, has six protons, but the number of neutrons in carbon atoms can vary from six to seven or eight. Each variation is an isotope of carbon.

Zare had the idea that it could be possible to distinguish different isotopes by the colors of light from the laser that they absorb when the original molecules are converted to smaller molecules through combustion.

"Think of them as being balls of different color," said Zare the Marguerite Blake Wilbur Professor in Natural Science and chair of the chemistry department. The tool can calculate the ratio of isotopes in a sample by simply "counting the colors and comparing them." This principle also makes the instrument more versatile than current mass spectrometers because Zare's device can analyze isotopes of different elements at the same time without being re-calibrated..

The equipment needed for the new method is smaller, cheaper, lighter and more portable than previous methods, and is easier to use. It has the potenti
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