I know that molecules can absorb light through electronic and vibrational excitations, which certainly increase the internal energy of a molecule. This idea is always connected to the quantum theory in my head (transition between discreet levels by absorbing a photon with a certain energy etc.) Now, in the most basic classical picture, temperature of let's say a liquid is basically average kinetic energy of all molecules or their average velocity.
What I cannot see is how a photon may give a molecule an actual momentum to increase its kinetic energy and consequently increase the temperature? I mean it can excite an electron in the molecule or make it vibrate, but as a whole the molecule does not really move faster. Or is it the acoustic vibrational modes that give the molecule an actual kick? I mean they should still be vibrations, but at least the vibrations which involve moving molecule as a whole.