BET theory (Brunauer-Emmett-Teller)

The BET (Brunauer-Emmett-Teller) theory describes how gases, like nitrogen, adsorb onto the surface of materials, such as porous solids. It helps determine the surface area by measuring how much gas the material can hold at different pressures. The theory assumes gas molecules form layers over the surface, stacking up to multiple layers, and uses this information to calculate the total surface area. This is important in fields like catalysis, material science, and environmental testing, providing insight into the material's capacity and efficiency based on its surface characteristics.