Is photon phase a factor in absorption

MikeGomez

The Hpyerphysics site, while discussing coherent light of lasers, says that…
“the emitted photons are "in step" and have a definite phase relation to each other.”

So now I wonder about electrons of an atom absorbing photons. Assuming the correct energy level for a given photon, is the probability of an electron getting excited to a higher energy level dependant on the phase of the photon, and/or the phase of the electron?

What about polarity. Is that a factor?

Is there theoretical evidence of experimental evidence one way or the other?

References would be greatly appreciated, as Google searches for this brings up all kinds of unrelated stuff.

M Quack

Don't know about lasers, but for x-rays this is well known.

The x-ray standing waves technique uses the fact that absorption depends on the phase of a standing wave in a crystal. The effect arises because absorption is higher at the maximum of the standing wave where the electric field is high, and lower at the "knots" of the standing wave. The phase can be tuned by rocking the crystal through the Bragg condition.

http://en.wikipedia.org/wiki/X-ray_standing_waves

Absorption also depends on the polarization of the wave (if that is what you mean by polarity). This effect is called dichroism and exists for visible light as well as for other wavelengths, including x-rays. Dichroism is related to birefringence.

http://en.wikipedia.org/wiki/Dichroism (second meaning)

MikeGomez

Excellent,

Thanks M