Detecting Gold Nanoparticles through Polarized Light: An Experiment Explanation

In summary, the conversation discusses an experiment with Colloidal gold to create gold nanoparticles. The method for detecting the nanoparticles is by shining polarized light on it from a 90 degree angle. By doing so, the light is unable to pass through the glass, indicating the presence of nanoparticles. The Tyndall effect may explain why the light cannot be seen, as it is scattered by the nanosized particles.
  • #1
lo2
We a did an experiment with Colloidal gold, in which we created gold Nano particles. Our teacher told us that we could detect that we had created nanoparticles by shining polarized light on it. We shined light on it from a 90 degrees angle and then we could not see the light on the other side of the glas as if something inside had stopped the light. Could you please exlpain to me why that proves we have created nanoparticles?
 
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  • #2
lo2 said:
We a did an experiment with Colloidal gold, in which we created gold Nano particles. Our teacher told us that we could detect that we had created nanoparticles by shining polarized light on it. We shined light on it from a 90 degrees angle
90 degrees to what? Please describe or draw the setup so it's clear what angles and direction we are talking about.

... and then we could not see the light on the other side of the glas as if something inside had stopped the light. Could you please exlpain to me why that proves we have created nanoparticles?
It's hard to tell exactly what is being observed. If you're just looking for a beam of light inside the colloid (the direction of the beam perpendicular to your line of sight) and don't see it because the colloidal particles are nanosized, then you want to look up the Tyndall effect.
 
  • #3


This experiment is based on the principle of light scattering, where the particles in the colloid (in this case, gold nanoparticles) interact with the incident light and scatter it in different directions. When polarized light is shined on the colloid at a 90 degree angle, the scattered light becomes polarized in the same direction as the incident light. This means that the scattered light is no longer able to pass through a polarizing filter placed on the other side of the glass, as its polarization is now perpendicular to the filter.

This phenomenon is known as polarized extinction and is commonly used to detect the presence of nanoparticles in a colloid. In this case, the lack of light passing through the filter indicates that the particles in the colloid are of a size range that is comparable to the wavelength of the incident light, which is characteristic of nanoparticles.

Therefore, by observing the polarized extinction of light in the experiment, it can be concluded that the colloid contains nanoparticles. This is because only particles in the nanoscale range have the ability to interact with light in such a way that it becomes polarized and can be detected using this method. Hence, the experiment provides evidence that gold nanoparticles have indeed been created.
 

1. What are gold nanoparticles and why are they important?

Gold nanoparticles are tiny particles made of gold with a diameter of less than 100 nanometers. They are important because they have unique properties such as high surface area to volume ratio, which makes them useful in various fields such as medicine, electronics, and environmental science.

2. How can gold nanoparticles be detected through polarized light?

Gold nanoparticles exhibit a phenomenon called surface plasmon resonance, which is the collective oscillation of electrons in the nanoparticle when exposed to light. This phenomenon can be detected through polarized light, which measures changes in the angle of light as it passes through the sample.

3. What is the purpose of the experiment for detecting gold nanoparticles through polarized light?

The purpose of the experiment is to demonstrate the surface plasmon resonance phenomenon and how it can be used to detect the presence of gold nanoparticles. This experiment also allows for the quantification of the concentration of gold nanoparticles in a sample.

4. What materials are needed for this experiment?

The materials needed for this experiment include a spectrophotometer, polarizer, gold nanoparticle sample, cuvettes, and a light source. Optional materials include a computer or data logger for data collection and analysis.

5. What are the potential applications of this experiment?

This experiment can be applied in various fields such as biomedical research, environmental monitoring, and nanotechnology development. It can also be used to study the properties of different types of nanoparticles and their interactions with light, which can lead to the development of new technologies and materials.

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