30 Questions
What is the main cause of the blue color of the sky?
Scattered sunlight
What does Mie theory explain when particle size is greater than 10 times the wavelength of light?
Scattering changes with distortion in the forward scattering direction.
What information can be obtained from the intensity of the scattering pattern at various angles in light scattering?
Particle size information
What happens to light scattering intensity when particle size is less than 80 nm?
Light scattering from small particles is very weak.
What is used to identify a molecule or particle in solution using light scattering?
Static Light Scattering
What does Rayleigh scattering intensity depend on?
Scattering angle
What is the main consequence of the interaction between the electric field of light and a small particle or molecule?
Light scattering
What are the two types of interactions between light and molecules (small particles) in light scattering?
Elastic interaction (Rayleigh scattering) and inelastic interaction (Raman scattering)
What kind of interaction is Rayleigh scattering?
Elastic interaction
What is radiated in all directions during light scattering?
Energy
For what type of particles is Rayleigh theory applicable?
Small molecules and particles with diameters < λ/10
What is the approximate size limit for particles on which Rayleigh theory may be used for a He-Ne laser (λ = 633nm)?
Particles less than ~60 nm
What is the mechanism behind Dynamic Light Scattering (DLS) measurement?
Particles in solution moving due to Brownian Motion
How is the velocity of Brownian motion determined in DLS?
Analysis of the intensity fluctuation yields the velocity of Brownian motion.
What happens to the scattering intensity over a short timescale in DLS?
The scattering intensity fluctuates.
How does the correlation persist in DLS for large particles?
The signal changes slowly and the correlation persists for a long time.
What is the primary size distribution obtained from DLS measurement?
The intensity-weighted diameter distribution.
What role does a correlator play in DLS analysis?
It constructs the time autocorrelation function of the scattered intensity.
What is the relationship between the hydrodynamic diameter (dH) and the translational diffusion coefficient (D) in Dynamic Light Scattering (DLS)?
The hydrodynamic diameter (dH) is defined by the translational diffusion coefficient (D) in DLS.
How does the surface structure of a particle affect its hydrodynamic diameter (dH)?
Any change to the particle surface that affects diffusion speed will alter dH.
Explain the impact of the ionic concentration of the medium on the hydrodynamic diameter (dH) of a particle.
The ionic concentration can affect the polymer conformation, changing dH by several nanometres.
How is the hydrodynamic diameter (dH) of non-spherical particles calculated in Dynamic Light Scattering (DLS)?
The dH of non-spherical particles is calculated based on the equivalent sphere with the same diffusion coefficient.
What factors determine the hydrodynamic diameter (dH) of a particle in Brownian motion?
The surface structure, shape factor, and translational diffusion coefficient influence the hydrodynamic diameter (dH) of a particle.
How does the translational diffusion coefficient (D) relate to the hydrodynamic diameter (dH) in Dynamic Light Scattering (DLS)?
D can be used to calculate the hydrodynamic diameter (dH) through the Stokes-Einstein equation.
What type of distribution is rarely used due to the risk of huge errors?
Number distributions
In low concentration samples, what is the relationship between turbidity and concentration?
Turbidity is linear with concentration
What type of plot should be used for reporting the size of each peak in the distribution?
Intensity-size plot
Why may determining the correct particle concentration require several measurements at different concentrations?
To account for multiple scattering events
What type of data should be used for reporting the relative amounts of each peak in the distribution?
Volume distribution data
What is the main drawback of using an Electron Microscope (SEM and TEM) for observing nanoparticles?
Observing NPs individually is tedious
This quiz covers the characterization techniques used in functional nanostructured materials, from light scattering to electron microscopy. Learn about the different length scales and nano-tools involved in studying human hair, cells, atoms, and molecules.
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