What Are Good Low Work Function Materials for Photoelectric Effect Experiments?

In summary, the conversation revolves around an experiment testing the photoelectric effect and the search for a material with a lower work function to use. Suggestions such as using magnesium are made, but concerns about its oxide layer affecting the work function are also raised. The conversation ends with a suggestion to do some form of cleaning in vacuum.
  • #1
Lambduh
69
1
Hi Guys,

I wanted to do an experiment testing the photoelectric effect but am having trouble getting light with energy higher than ~4 eV(300nm) through my window into vacuum as it's made of BK7 instead of something like fused silica. Does anyone know of a good material to use with a work function lower than that so i can see some electrons?:)

Thanks!
 
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  • #3
Sorry i wasn't very clear. I have a Monochromater source with xenon/deuterium lamps. I want to shine light into a vacuum cell with a sample in it and then collect them at a positively biased cathode then read the current with a picoammeter. However the window on my vacuum cell doesn't transmit light below ~350nm so I'm trying to find a material that i can hit with ~3.5 eV photons and eject some electrons.

I can't seem to find a relatively stable compound with a low enough work function to use. I guess that makes sense because all of the stable compounds want to hold on to those electrons:) So any suggestions would be awesome.

Thanks again!:)

Mark
 
  • #4
Magnesium has a work function of around 3.7 eV. That is lower than your photon energy.

Zz.
 
  • #5
Hmm i'll definitely try it thanks! I'm curious though... because magnesium forms an oxide layer(which seems to be hard to remove) won't that affect the work function? Depending on the material I've read that even a monolayer of adsorbates can change the work function by up to ~1eV.

Thanks again:)
 
  • #6
Lambduh said:
Hmm i'll definitely try it thanks! I'm curious though... because magnesium forms an oxide layer(which seems to be hard to remove) won't that affect the work function? Depending on the material I've read that even a monolayer of adsorbates can change the work function by up to ~1eV.

Thanks again:)

Then you will have to do some form of cleaning, such as e-beam polishing, in situ in vaccum.

Zz.
 
  • #7
Cool. Thanks for the info Zz.
 

FAQ: What Are Good Low Work Function Materials for Photoelectric Effect Experiments?

What are low work function materials?

Low work function materials are substances that have a low threshold for releasing electrons, meaning they require less energy to remove an electron from their surface. This property makes them useful in a variety of applications, such as thermionic emission, field emission, and photoemission.

How are low work function materials used in thermionic emission?

In thermionic emission, low work function materials are used as the cathode in a vacuum tube. When heated, the material releases electrons, creating a current that can be used for various purposes, such as amplifying signals in electronic devices.

What is the advantage of using low work function materials in field emission?

In field emission, low work function materials are used to create a strong electric field that can be used to accelerate electrons. The low work function allows for a larger number of electrons to be emitted, resulting in a more efficient and powerful field emission process.

How are low work function materials used in photoemission?

In photoemission, low work function materials are used to convert light energy into electrical energy. When light hits the surface of the material, it excites electrons and causes them to be emitted, creating a current that can be used for various applications, such as solar cells.

What are some common examples of low work function materials?

Some common examples of low work function materials include cesium, strontium, barium, and alkali metals such as lithium, sodium, and potassium. These materials have work functions ranging from 2 to 3 electron volts, making them ideal for various applications in electron emission and photovoltaics.

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