Electron Ionisation: Electric Field Interaction & Efficiency

In summary, the electron beam in electron ionisation transfers energy to the molecule being ionised via the interaction of the electric fields of the electrons in the molecule and the beam. This is a resonance phenomenon, where the ionisation efficiency is maximised when the wavelength of the beam is equal to the bond lengths in the molecule. This is similar to pushing a child on a swing at the right rate to maximize their height.
  • #1
Orlando
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In electron ionisation, how does the electron beam transfer energy to the molecule being ionised? Is it via the interaction of the electric fields of the electrons in the molecule and the beam? If so, what type of interaction? And why is ionisation efficiency of the beam maximised when the wavelength of the beam is equal to that of the bond lengths in the molecule?
 
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  • #2


This is not my are of expertise, but no ones seems to be answering, so I will give it a stab. I believe you have a resonance situation. When the wavelength of the beam matches up with the molecule bond lengths, they are in resonance, and the molecule is much more able to absorb the energy. (If you are not familiar with resonance, think of pushing a child on a swing. You get the highest swings if your rate of pushing matches the rate of swinging).
 

FAQ: Electron Ionisation: Electric Field Interaction & Efficiency

1. What is electron ionisation and how does it work?

Electron ionisation is a process in which high energy electrons are used to ionize atoms or molecules. This is done by colliding the electrons with the sample molecules, causing them to lose an electron and become positively charged ions.

2. What is the role of an electric field in electron ionisation?

An electric field is used in electron ionisation to accelerate the high energy electrons towards the sample molecules. This increases the chances of collision and ionization occurring.

3. How does the efficiency of electron ionisation depend on the strength of the electric field?

The efficiency of electron ionisation increases with the strength of the electric field. This is because a stronger electric field can accelerate the electrons to higher energies, resulting in more collisions and ionisation events.

4. What factors can affect the efficiency of electron ionisation?

The efficiency of electron ionisation can be affected by the strength of the electric field, the type of sample being ionized, and the temperature and pressure of the ionization chamber. Additionally, the energy and direction of the electrons, as well as any interfering compounds in the sample, can also impact the efficiency.

5. How is electron ionisation used in analytical techniques?

Electron ionisation is commonly used in mass spectrometry, a powerful analytical technique used to identify and quantify molecules in a sample. In this technique, the ions produced by electron ionisation are separated and detected based on their mass-to-charge ratio, providing valuable information about the composition of the sample.

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