Tuning of the wavelength of a helium–neon laser from 3.3912 to 3.3922 μ

An investigation was made of the competition between the λ₀ = 3.3912 μ and λ₁ = 3.3922 μ lines emitted by a helium–neon laser. The theoretical output power at the wavelength λ₁ was found to be 50% of the output at λ₀. The experimental value was 40%. The rate of decay of the lower level of the λ₁ line was determined and it was found that the rates of decay of the lower levels of both lines were independent of the pressure.