Chemistry

Microscopic Window Washing

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Science  05 Jun 2009:
Vol. 324, Issue 5932, pp. 1243
DOI: 10.1126/science.324_1243b

High-resolution imaging of organic polymers in a transmission electron microscope (TEM) is hampered by the accumulating residue of electron beam–induced sample decomposition. Horiuchi et al. solve this problem through gentle cleaning of their microscope with oxygen radicals generated in a low-temperature plasma near one of the accessory ports. An extra pumping system added at the objective aperture pulled the oxygen radicals into the sample chamber. The authors used their TEM to examine brushes of a phosphorylcholine that had been grafted onto silicon nanoparticles via a surface initiator. Once oxidation (and hence volatilization) of the residue cleared the field, they could see the brushes extending from a nanoparticle, and even visualize the intermingling of brushes in two neighboring particles. Mapping of the intensity profiles distinguished the initiator, with a high carbon density near the particles and the broader brushes where the carbon density was lower.

ACS Nano 3, 1297 (2009).

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