I have a doubt regarding energy levels. I saw that translational energy levels are quasi-continuous, rotational energy levels are discrete and vibrational energy levels are more discrete. I want to ask what does this energy level describe. This question is related to specific heat of gases.
For example, if we take a diatomic molecule under consideration, only 2 rotational degrees of freedom are possible. So max levels occupied will be 2, i.e the 1st and 2nd. Am I correct or these levels signify something else?
My thought is wrong. I figured it out that as temperature increases, molecules begin to occupy higher energy levels. But then tell me one thing. The total energy contribution by a single molecule for rotational is $K_bT$ at temperature $T$. So does this mean the energy level it occupies also has energy $K_bT$? But then, if we increase temperature by $t$ the new energy will be $K_b(T+t)$. But then, how do we know that it will correspond to energy of one of the band?