Authors: GERD H. WOEHRLE, JAMES E. HUTCHISON, SAİM ÖZKAR, RICHAD G. FINKE
Abstract: The need to easily and quickly count larger numbers of nanoparticles, in order to obtain statistically useful size and size-distribution data, is addressed via the use of a readily available, free, public-domain program for particle counting, NIH-Image (and 2 others derived from it, Scion Image and Image J), collectively referred to herein as Image. The best protocols that we have found useful for the use of Image are reported; both appropriate as well as problematic applications of Image are then illustrated with a series of TEM images of Ir(0), Pd(0) and Au(0) nanoclusters. Methods to detect and image nanoclusters with sub-1-nm core diameters are reported and illustrated in the literature with Au nanoclusters, an important problem since the literature indicates that subnanometer Au nanoclusters are often present, but undetected. A list of suggestions and caveats for the appropriate use of Image is also provided, since this contribution is directed at first-time users who are not presently using nanoparticle imaging software. The reader is also reminded of several, well-known caveats for the use of TEM in obtaining size data for nanostructures. Overall, Image is a free, public-domain program that is useful for the rapid counting of large numbers of particles.
Keywords: Nanoparticles, Particle size distributions, Transmission Electron Microscopy, Image analysis, Image (NIH-Image, Scion Image, Image J), Histograms
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