Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Transmittance electron microscopic (TEM) images of: (a) polygonal (small); and (b) cubic-like (large) NaYF4 nanocrystals. The average dimension for (a) was calculated based on 100 nanoparticles selected from a TEM micrograph. Upconversion fluorescence images (c) and spectra (d) of the: (i) core; and (ii) core-shell nanocrystals, under 980-nm laser excitation. The spectra recorded by a CCD imaging spectrometer exhibits UV, blue, red, and NIR wavelengths simultaneously.
