![Autocorrelation Equations
• Measures how similar the signal
is to itself after a time delay.
Where,
•I(t): Intensity of scattered light at time t.
•I(t+ τ) Intensity at later time, after delay τ.
•⟨⋅⟩ Averaging over time.
•G(2)
(τ ): Autocorrelation function
Equation
G(2)
(τ)=⟨I(t) I(t+
⋅ τ)⟩/⟨I(t)⟩2
Decay of correlation
G(2)
(τ)=A[1+βe−2Γτ
]
Where,
•A: Baseline of the signal.
•β: Coherence factor (instrument-specific).
•Γ: Decay rate (related to diffusion).
•τ: Time delay.
Link to particle Motion
Γ=Dq2
Where,
• D: Translational diffusion coefficient (how fast the particles move).
• q: Scattering vector (depends on laser wavelength and scattering angle).
q={4πn
sin(θ/2
)}/λ
• n: Refractive index of medium.
• λ: Laser wavelength.
• θ: Scattering angle.](https://image.slidesharecdn.com/dls12349922-250626123847-3c91b1dc/85/DLS-AND-Zeta-how-correlation-effects-the-size-of-nanoparticle-5-320.jpg)
DLS AND Zeta how correlation effects the size of nanoparticle
- 1. Title- DLS and Zeta
- 2. Dynamic Light Scattering (DLS) •Principal- DLS measures the Brownian motion of the particles in a dispersion and uses this information to determine their hydrodynamic size using scattering.
- 5. Autocorrelation Equations • Measures how similar the signal is to itself after a time delay. Where, •I(t): Intensity of scattered light at time t. •I(t+ τ) Intensity at later time, after delay τ. •⟨⋅⟩ Averaging over time. •G(2) (τ ): Autocorrelation function Equation G(2) (τ)=⟨I(t) I(t+ ⋅ τ)⟩/⟨I(t)⟩2 Decay of correlation G(2) (τ)=A[1+βe−2Γτ ] Where, •A: Baseline of the signal. •β: Coherence factor (instrument-specific). •Γ: Decay rate (related to diffusion). •τ: Time delay. Link to particle Motion Γ=Dq2 Where, • D: Translational diffusion coefficient (how fast the particles move). • q: Scattering vector (depends on laser wavelength and scattering angle). q={4πn sin(θ/2 )}/λ • n: Refractive index of medium. • λ: Laser wavelength. • θ: Scattering angle.
- 6. Zeta Principle: The instrument applies an electric field to a sample containing charged particles. As particles move (migrate) due to the electric field, their velocity is measured by analyzing the Doppler shift of scattered laser light. This velocity is then used to calculate electrophoretic mobility, and ultimately the zeta potential.
- 7. Thank You