In this presentation, I included the types of scattering first then I focused the DLS

1. BY
I.G.Shanmugapriya
Junior Research Fellow
C/O , Dr. Rohit Kumar Rana,
Nanomaterials Laboratory,
CSIR-IICT, Hyderabad.
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fg

4. Tightly packed ceramic
has high zeta potential
To find the rate of flocculation respect to change
in pH in the Waste water treatment process
Stability of the emulsion
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5. The 2nd Virial Coefficient (A2) is a property describing the interaction strength between
the particles and the solvent or appropriate dispersant medium.
A2>0 means the
particles ‘like’ the
solvent more than
itself, and will tend
to stay as a stable
solution
A2=0 means the
particle-solvent
interaction strength
is equivalent to the
molecule-molecule
interaction
When A2 <0
means the
particle ‘likes’
itself more than
the solvent, and
therefore may
aggregate
SIZE
MEASUREM
ENT
(DIAMETER)
0.3 nm
to 10 µm
SIZE
RANGE FOR
ZETA
POTENTIAL
(DIAMETER)
3.8 nm
to 100
µm
MOLECULA
R WEIGHT
(DALTONS)
342 Da
to 2x107
Da
Liquid
Medium
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7. REFLECTION : The bouncing of light or
sound waves off of a surface.
REFRACTION : The bending of light or
sound wave as it passes between two
substances.
SCATTERING : Light or sound wave
interact with matter causing it move in
various directions.
ABSORPTION: The transfer of light
energy to particles of matter.
TRANSMITTANCE: All the light passes
through a solution without any
absorption.
DIFFRACTION : The bending of waves
around the edges of the object.
INTERFERENCE: The combination of
two or more electromagnetic
waveforms to form a resultant wave in
which the displacement is either
reinforced or cancelled.
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8. Elastic
Scattering
• Wavelength of scatter light same as incident light
• Examples: Rayleigh Scattering, Mie Scattering,
Non-selective scattering.
Inelastic
Scattering
• Wavelength of scatter light different as incident light
• Examples: Raman Scattering, Fluorescence,
compton scattering and brillouin scattering
Quasi-
elastic
Scattering
• Wavelength of the scattered light shifts
• Moving matter due to Doppler effects
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9. REF: https://www.nanophoton.net/raman/raman-spectroscopy.html
Fluorescence
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10. RAYLEIGH SCATTERING/ MOLECULAR
SCATTERING
 The scattering by molecules and particles whose
diameters are << wavelength of the light.
Examples: primarily due to oxygen and nitrogen
molecules.
 scattering intensity is proportional to Four times
of wavelength it is responsible for blue sky
•This equation indicates the ratio of light that is
deflected in the direction. The intensity of the
scattering depends on the wavelength of the
incoming light.
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11. MIE/DEBYE SCATTERING
The scattering by molecules and
particles whose diameters
>>=wavelength of the light.
 This is responsible for white color
for the clouds and white scattering
near the sun can be attributed to Mie
scattering, which is not wavelength
dependent.
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12. • Non-selective scattering occurs when the
diameter of the particles causing scatter are
much larger than the wavelengths being
sensed.
• Water droplets, that commonly have
diameters of between 5 and 100 m, can cause
such scatter, and can affect all visible and near
- to - mid-IR wavelengths equally.
Scattering
process
Particle size
(µm)
Wavelength
dependence
Kind of Particle
Rayleigh <<0.1 -4 Air molecule
Mie 0.1 to 10 -4 to 0 Smoke ,cloud
droplets.
Non selective 10 0 Larger dust,
Water droplets.
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13. INELASTIC SCATTERING
Compton scattering Brillouin scattering
• It is inelastic scattering
where the frequency of the
reflected radiation is
changed by thermal sound.
•
• Brillouin frequency (B)
shift the refractive index n,
the acoustic velocity va, and
the vacuum wavelength λ:
B = 2n a/ 
i is wavelength of incident photon
f is wavelength of scattered photon
h – plank constant
M – mass of electron
C – Velocity of electron
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14. NANO
DECI
CENTI
MILLI
MICRO
femto
PICO
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15. Orthogonal Techniques
Particle Size Range
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18. Dynamic Light Scattering (DLS)/ photoelectron correlation spectroscopy (PCS)
/Quasi-elastic Light Scattering (QLS)
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20. LASER
DETECTOR
LASER
DETECTOR
CONSTRUCTIVE
INTERFERENCE
DISTRUCTIVE
INTERFERENCE
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22. Debye plotRayleigh Scattering equation
sample at different concentrations and applying
the Rayleigh equation then Intensity Vs conc
(debye plot) Slope is A2 Intercept (C=0) inverse
of molecular weight.
R : The Rayleigh ratio - the ratio of
scattered light to incident light of the
sample.
M : Sample molecular weight.
A2 : 2nd Virial Coefficient.
C : Concentration.
P : Angular dependence of the
sample scattering intensity.
K : Optical constant.
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23. Particles with more positive than +30 Mv
or more negative than -30 Mv are stable. 23

24. When an electric field is applied
to the cell, any particles moving
through the measurement
volume will cause the intensity
of light detected to fluctuate
with a frequency proportional to
the particle speed.
Therefore LDS is placed to
measure the velocity of particle
moving through a fluid in an
electrophoresis.
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25. z : Zeta potential.
UE : Electrophoretic mobility.
e- Dielectric constant.
h-Viscosity.
ƒ(Ka) : Henry’s function.
Two values are generally used as approximations for the f(Ka)
determination - either 1.5 (smoluchowski approximation for larger particle
with aqueous sample ) or 1.0 (Huckel approximation for smaller particle
with non aqueous sample)
Zetasizer Nano series calculates the zeta potential by determining the
electrophoretic mobility (velocity of particle in the electric field) and then apply
to henry equation.
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26. STATIC LIGHT SCATTERING DYNAMIC LIGHT SCATTERING
SLS measures the dependence of
the average scattered intensity on
the scattering angle
DLS measures the time
autocorrelation of the scattered
light intensity g(2) (r) as a function
of the delay time T
Structural information about the
particles, including the size, shape
and molar mass.
DLS provide dynamic information
about the particles in dispersion
including translational, rotational
and internal motion
SLS measures the amplitude of
scattering, regardless of its
fluctuations.
DLS measures how scattering
changes over time, regardless of
the amplitude
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