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Analytical Chemistry

Chemistry In Pictures

Chemistry In Pictures

January 18, 2016 | A version of this story appeared in Volume 94, Issue 3

Selections from cen.chempics.org, where C&EN showcases the beauty of chemistry

SNOW ON THE LEAVES
A microscope image resembles a snow-covered tree.
Credit: David Maitland
This image isn’t a painting of snow falling on bare trees; it’s a leaf of black witch hazel (Trichocladus crinitus) imaged at 100× magnification. Crystals of calcium oxalate growing between the leaf’s ribs are the “snow” in this image, which was taken using differential interference contrast (DIC) microscopy and submitted to the Royal Photographic Society’s International Images for Science contest. The crystals grow out of the leaf and irritate herbivores that eat them, providing a natural defense for the plant. In DIC micrographs, brightness indicates how fast light passes through each part of a specimen under the microscope, allowing scientists to determine which parts have the same chemical makeup.—Manny Morone
LIQUID CRYSTAL
[+]Enlarge
Credit: David Allan/University of Hull
Liquid crystals consist of rodlike molecules that orient themselves like crystals but flow like liquids. Depending on conditions, these substances exist in different phases, the least ordered of which is the nematic phase. When viewed under a polarized light source with a microscope, a liquid crystal displays unique optical properties that give it an array of interference colors that change with shifts in temperature, thickness, and orientation of the sample. The stark difference between the two microscope images of nematic liquid crystals shown here results from only a 1 °C drop in temperature from top to bottom.—Craig Bettenhausen
A pattern in shimmering liquid is brassy in color on top, blues and blacks on bottom.
Credit: David Allan/University of Hull
Liquid crystals consist of rodlike molecules that orient themselves like crystals but flow like liquids. Depending on conditions, these substances exist in different phases, the least ordered of which is the nematic phase. When viewed under a polarized light source with a microscope, a liquid crystal displays unique optical properties that give it an array of interference colors that change with shifts in temperature, thickness, and orientation of the sample. The stark difference between the two microscope images of nematic liquid crystals shown here results from only a 1 °C drop in temperature from top to bottom.—Craig Bettenhausen
[+]Enlarge
Credit: David Allan/University of Hull
A pattern in shimmering liquid is brassy in color on top, blues and blacks on bottom.
Credit: David Allan/University of Hull

To enter our photo contest, visit cen.chempics.org or e-mail CENChemPics@acs.org.

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