Photon wavelength quantization?

[espen180]

Are photon wavelengths quantizised? If so, what are their possible wavelengths? Do their possible wavelengths also depend on the system they are in?

 

[f95toli]

Are photon wavelengths quantizised? If so, what are their possible wavelengths? Do their possible wavelengths also depend on the system they are in?

No, they are not. The "wavelength" of a photon (which btw is a slightly ambigous measure) is not quantized. The usual "classical" relation between frequency and wavelength (lamba=c/f) applies even to single photons; quantum mechanics only adds the relation W=hf for the energy of a single photon.

 

[Jano L.]

Wavelength of a free radiation is not restricted. However, stationary waves in optical resonators have wavelengths quantised. Consider stationary wave in long metal resonator of the length $$l$$. It can have only such a wavelength, for which the condition

$$l = n \frac{\lambda}{2}$$

is satisfied for some whole integer $$n$$.