Question

Calculate the half-width of a spectral line of wavelength λ = 550 nm when the
temperature of the gas is 6 × 105 K. Assume H atoms to be emitters.

Answer 1

The line shape is Gaussian; the full width at half maximum intensity in Å,

$$\Delta\lambda_{1/2}^D = (7.16\times10^{-7})\,\lambda(T/M)^{1/2}\quad (1)$$

where T is the temperature of the emitters in K, and M the atomic weight in atomic mass units (amu)

In our case, λ = 550 nm, T=6 × 10⁵ K, M=1 amu

Using (1) we got:

$$\Delta\lambda_{1/2}^D = 3 Å$$

Answer:

$3\times10^{-10}$