Gaseous scent molecules

Gaseous scent molecules are odorants that have transitioned into the gas phase and mix with the air. They exist as individual molecules or very small molecular aggregates that move freely among the air molecules.

Their spread within a space occurs predominantly through diffusion: the scent molecules spread from regions of high concentration (e.g., the perfume source) to regions of lower concentration until an approximately uniform distribution has been established. The higher the temperature and the smaller the molar mass of the scent molecule, the faster this spread is. Air currents (convection, drafts, ventilation) are superimposed on diffusion and can transport odor plumes in a directed manner.

Gaseous scent molecules are perceived when they enter the nasal cavity with the airflow and bind to olfactory receptors there. The fact that odors from a source become noticeable throughout an entire room within a short time is an illustrative example of gas diffusion in combination with air movement.