The vibrational theory of olfaction, proposed by Luca Turin in 1996, suggests that the odor of a molecule is determined by its vibrational frequencies rather than solely by its shape, as traditional theories suggest. According to this theory, olfactory receptors in the nose can detect the specific vibrational frequencies of odor molecules through a process called inelastic electron tunneling spectroscopy (IETS).
In IETS, an electron from the olfactory receptor tunnels through the energy barrier of the odor molecule. If the electron’s energy matches the vibrational energy of the molecule, the electron can transfer some of its energy to the molecule, causing it to vibrate. This vibrational energy is then detected by the receptor, leading to the perception of a specific odor.