Rami Arieli: "The
Laser Adventure" Chapter 2.5 page 5
Example 2.3:
Calculate the ratio of the population numbers (N1, N2)
for the two energy levels E2 and E1 when the material
is at room temperature (3000K), and the difference between the
energy levels is 0.5 [eV]. What is the wavelength (l)
of a photon which will be emitted in the transition from E2
to E1?
Solution to example 2.3:
When substituting the numbers in the equation,we get:
= 4 * 10-9
This means that at room temperature, for every
1,000,000,000 atoms at the ground level (E1), there are 4 atoms
in the excited state (E2) !!!
To calculate the wavelength:
This wavelength is in the Near Infra-Red (NIR) spectrum.
Question 2.4:
A material is in thermodynamic equilibrium at room temperature (3000K).
The wavelength of the photon emitted in the transition between two
levels is 0.5 [mm] (visible radiation).
Calculate the ratio of the population numbers for these energy levels.