Do intramolecular bonds vibrate in solids...??? In case of molecular solids does the Intramolecular bonds(bonds within atoms of a molecule) vibrate as they do vibrate in gas and liquid phases. We are familiar that motion of molecules in solids is in form of vibrations. But when we talk of that we are normally speaking about inter-molecular vibrations(phonons) Now, we know that intermolecular bonds are held together by weak forces like Van Der Walls' forces,London Dispersive forces,etc. While the intra-molecular forces are generally strong forces like covalent bonding,dipole-dipole forces,etc. "Also when we heat a solid(of molecular nature), it is easy to envisage that intermolecular vibrations increases. But on heating does intra-molecular vibrational transtions to higher vibrational energy states also takes place as on heating a gas comprised of molecules." "Also does the energy gap between various intramolecular vibrational states(If they exist) in solids , remains the same as the energy gap between different vibrational levels in gases and liquids.???" "Thanks For Reading and Paying Attention"