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At left, a structural model of a typical silicon nanocrystal (yellow) stabilized within an organic shell of cyclohexane (blue). At right, a high-resolution transmission electron microscope photograph of a single silicon nanoparticle.
Credit: NIST
If it's true that good things come in small packages, then the National Institute of Standards and Technology (NIST) can now make anyone working with nanoparticles very happy. NIST recently issued Reference Material (RM) 8027, the smallest known reference material ever created for validating measurements of these man-made, ultrafine particles between 1 and 100 nanometers (billionths of a meter) in size.
RM 8027 consists of five hermetically sealed ampoules containing one milliliter of silicon nanoparticles—all certified to be close to 2 nanometers in diameter—suspended in toluene. To yield the appropriate sizes for the new RM, the nanocrystals are etched from a silicon wafer, separated using ultrasound and then stabilized within an organic shell. Particle size and chemical composition are determined by dynamic light scattering, analytical centrifugation, electron microscopy and inductively coupled plasma mass spectrometry (ICP-MS), a powerful technique that can measure elements at concentrations as low as several parts per billion.
NIST: World’s Smallest Reference Material is Big Plus for Nanotechnology
Michael E. Newman
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