Nanotechnology-Enabled Sensors

240 Chapter 5: Characterization Techniques for Nanomaterials
Counts (arbitrary units)
20
30
40
2θ
50
Fig. 5.23 Left: Powder XRD spectra of a series of InAs nanocrystal sizes. From
the width of the reflections the crystalline domain size may be calculated. 22 Right:
Powder X-ray diffraction of a series of InP nanocrystal sizes. The stick spectrum
at the bottom gives the bulk reflection position with relative intensities. Reprinted
with permission from the American Chemical Society publications. 57
5.6 Light Scattering Techniques
60
70
80
These techniques involve analyzing the light that is scattered from materials.
The types of light scattering include: elastic, where the wavelength of
the scattered light remains unchanged from the incident light, and inelastic,
where the scattered light’s wavelength is different from that of the
incident light. Depending on the frequency of light and the type of scattering,
these techniques can provide information regarding the size, chemical
composition and structure of nanomaterials. Changes in these material
properties can be monitored with such techniques, and in some cases, the
technique itself may be used for signal transduction in sensing applications.
Rayleigh scattering, which occurs when the particles are much smaller
than the wavelength of the impinging light, is an example of elastic scatter-
Counts (arbitrary units)
20 30 40 50 60
2θ