Comparison To Dynamic Light Scattering
Both dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA) measure the Brownian motion of nanoparticles whose speed of motion, or diffusion constant, Dt, is related to particle size through the Stokes–Einstein equation.
where
- Dt is the diffusion constant, a product of diffusion coefficient D and time t
- is Boltzmann's constant,
- T is the absolute temperature,
- η is viscosity
- d is the diameter of the spherical particle.
In NTA this motion is analyzed by video – individual particle positional changes are tracked in two dimensions from which the particle diffusion is determined. Knowing Dt, the particle hydrodynamic diameter can be then determined.
In contrast, DLS does not visualize the particles individually but analyzes, using a digital correlator, the time dependent scattering intensity fluctuations. These fluctuations are caused by interference effects arising from the relative Brownian movements of an ensemble of a large number of particles within a sample. Through analysis of the resultant exponential autocorrelation function, average particle size can be calculated as well as a polydispersity index. For multi-exponential autocorrelation functions arising from polydisperse samples, deconvolution can furnish limited information about the particle size distribution profile.
Read more about this topic: Nanoparticle Tracking Analysis
Famous quotes containing the words comparison, dynamic, light and/or scattering:
“Certainly there is not the fight recorded in Concord history, at least, if in the history of America, that will bear a moment’s comparison with this, whether for the numbers engaged in it, or for the patriotism and heroism displayed.”
—Henry David Thoreau (1817–1862)
“The nearer a conception comes towards finality, the nearer does the dynamic relation, out of which this concept has arisen, draw to a close. To know is to lose.”
—D.H. (David Herbert)
“and wife or husband
who does not lock the door of the marriage
against you, finds you
not as unwelcome third in the room, but as
the light of the moon on flesh and hair.”
—Denise Levertov (b. 1923)
“Or of the garden where we first mislaid
Simplicity of wish and will, forgetting
Out of what cognate splendor all things came
To take their scattering names;”
—Richard Wilbur (b. 1921)