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:
“What is man in nature? A nothing in comparison with the infinite, an all in comparison with the nothing—a mean between nothing and everything.”
—Blaise Pascal (1623–1662)
“Knowledge about life is one thing; effective occupation of a place in life, with its dynamic currents passing through your being, is another.”
—William James (1842–1910)
“The One remains, the many change and pass;
Heaven’s light forever shines, Earth’s shadows fly;
Life, like a dome of many-coloured glass,
Stains the white radiance of Eternity,
Until Death tramples it to fragments.”
—Percy Bysshe Shelley (1792–1822)
“A committee is organic rather than mechanical in its nature: it is not a structure but a plant. It takes root and grows, it flowers, wilts, and dies, scattering the seed from which other committees will bloom in their turn.”
—C. Northcote Parkinson (1909–1993)