Einstein coefficients/ equivalent phrase

1. Mar 7, 2013

mikeph

Hi

Is it technically sound to state that the rate of absorption of photons at a given frequency is proportional to the number of photons at that frequency?

most statements of the B coefficients seem to focus on molecular state populations, but I'm reasoning that for every state change n1--->n2 there must also be one less photon?

edit- is it also sound to say the number of photons at that frequency is proportional to the intensity of light? I think this should be correct, just double checking. Brain has switched off.