Calculating Mean Free Path of N2 Molecule in UHV Chamber

In summary, the mean free path of an N2 molecule in an ultra-high-vacuum chamber at a pressure of 10-10mbar can be calculated using the equation λ=kT/(√2)πpd2, where n is the number density, σ is the collision cross-section, p is the pressure, and d is the molecular diameter. While the temperature T is not given, it can be assumed to be a standard value such as 0°C for reference data.
  • #1
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Homework Statement


What is the mean free path of an N2 molecule in an ultra-high-vacuum chamber at a pressure of 10-10mbar?

Homework Equations


λ=1/(√2)nσ
number density n, collision cross-section σ
p=nkT
pressure p, temperature T
σ=πd2
d molecular diameter

The Attempt at a Solution


λ=kT/(√2)πpd2
where we know p and I can estimate d to be around 10-10m. However I am not given T, and I don't really see how I could know what it is...
 
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  • #2
albega said:
However I am not given T, and I don't really see how I could know what it is.
At which point, you're free to assume a temperature. What's a good standard temperature for reference data?
 
  • #3
Standard temperature, 0degc. Thanks.
 

What is the mean free path of a N2 molecule?

The mean free path of a N2 molecule is the average distance a molecule travels between collisions in a vacuum chamber.

How is the mean free path of a N2 molecule calculated?

The mean free path of a N2 molecule can be calculated using the formula: λ = kT / √(2) * π * d^2 * P, where λ is the mean free path, k is the Boltzmann constant, T is the temperature, d is the molecular diameter, and P is the pressure.

Why is it important to calculate the mean free path of N2 molecules in a UHV chamber?

It is important to calculate the mean free path of N2 molecules in a UHV chamber because it helps in understanding the behavior of gas molecules in the chamber and can aid in optimizing experimental conditions for various processes.

What factors can affect the mean free path of N2 molecules in a UHV chamber?

The mean free path of N2 molecules in a UHV chamber can be affected by factors such as temperature, pressure, and the size of the chamber. Higher temperatures and lower pressures can result in longer mean free paths, while a smaller chamber size can decrease the mean free path.

Can the mean free path of N2 molecules in a UHV chamber be experimentally measured?

Yes, the mean free path of N2 molecules in a UHV chamber can be experimentally measured using techniques such as laser absorption spectroscopy or gas flow measurements.

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