# 100 Nano-Stories: Single Scattering Albedo!

## Episode #66: Definition + Applications In Aerogel Models!

# Preface! ✨

It’s your favorite material science & nanotechnology enthusiast! Time to explain more of the optical interactions between light and the transparency of aerogel!

**I highly recommend you read the previous article to understand the fundamentals of optical depth and how it plays a huge role in the transparency of aerogels! 😃**

Don’t worry, the article below is only 4 minutes long!

But for now, let’s cover more about what the single scattering albedo is all about!

# Single Scattering Albedo Explained! 💡

## Definitions! 🔑

**Single-Scattering Albedo **is used to define the scattering and absorption in a medium/material.

The equation for the single scattering albedo is shown below:

## ωλ** = σ(s)/ β(e)**

This may confuse some of you quickly, but let me explain each letter.

**ω = Single-Scattering Albedo symbol.**

**σ(s) = The Scattering Coefficient.**

**β = The Extinction Coefficient.**

The extinction coefficient **(β(e)) **is the sum of the absorption coefficient **(β(a)) **and the scattering coefficient **(β(s)). **This will lead to the extinction coefficient to look something like this:

**(β(a) + β(s) = β(e))**

So if it helps, we can rearrange the single scattering albedo equation like this:

However, the output of **“ω” **can only be between 0 and 1.

- If
**“ω”**is 0, the medium/material will absorb everything (particles, photons, etc.). - If
**“ω”**is 1, the medium/material will scatter everything (particles, photons, etc.).

The final main piece of information that I want to give you is that **“ω” **is being used for the scattering of light in transparent aerogels. In this case, we want to use the subscript **“λ”. **So when discussing aerogels, we will commonly use this to describe the single scattering albedo:

## ω(λ)

**“λ”** is the symbol for wavelengths of light. The unit to measure wavelengths of light is meter **(m). **But sometimes, we will often use nanometers to measure wavelengths of light **(nm, m^-9).**

# Closing Thoughts! 💭

We are 2/3 of the way complete with explaining the fundamental concepts of the theoretical equation proposed by MIT!

The last steps are Isotropicity, Rayleigh Scattering Equation, and the Beer-Lambert Law! ✌🏽

# Vocabulary! 📓

** Optical Depth → **The quantity of light that has been removed due to absorption, scattering, and reflection;

**τ.**

** Transparency → **All the light will pass through a material, and it won’t be reflected, absorbed, or scatter in a material.

** Absorption → **The light is absorbed by the aerogel particles.

** Isotropic → **A specific property of a medium/material is the same (or uniform) in all directions.

** The Extinction Coefficient → **A sum of the absorption coefficient and the scattering coefficient;

**β(e).**

** Single-Scattering Albedo →** Defines the scattering and absorption in a medium/material.

** Absorption Coefficient** →

**(β(a))**

** Scattering Coefficient** →

**(β(s))**

*Wavelength Symbol → *λ

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*© 2021 by Carlos Manuel Jarquin Sanchez. All Rights Reserved.*