The continuous part of the x ray spectrum is due the deceleration of electrons. I know that a decelerating charged particle emits a braking radiation according the EM theory. However, what's in the photon picture of light that says a decelerating charged particle must photons continuously? Why electrons colliding with the anode don't lose their energy exciting the atoms setting in there to some possible excited energy state instead?

The continuous part of the x ray spectrum is due the deceleration of electrons. I know that a decelerating charged particle emits a braking radiation according the EM theory. However, what's in the photon picture of light that says a decelerating charged particle must emit photons continuously? Why electrons colliding with the anode don't lose their energy exciting the atoms setting in there to some possible excited energy state instead?