rotational energy

In the gas phase, molecules can rotate. This rotation is quantized, meaning it can only occur at specific energy levels. For a rigid diatomic molecule, the rotational energy is described by the formula (E_J = J(J+1)(h^2/8\pi^2I)), where (I) is the moment of inertia and (J) is the rotational quantum number ((J = 0, 1, 2, \dots)). Transitions between these rotational energy levels result in the absorption or emission of radiation, forming molecular rotational spectra. These spectra are typically observed in the microwave region of the electromagnetic spectrum. Microwave spectroscopy allows scientists to determine precise molecular structures, including bond distances and angles, and investigate various molecular properties.12