Gas Sorption: Isotherm Concave to the p/po axis >Exhibited by microporous solids(< 2nm) >Exhibited by nonporous or macroporous solids(> 50nm) >Unrestricted monolayer-multilayer Type ll adsorption Point indicates the relative pressure at which monolayer coverage is complete P/PO S Lowell J. E. Shields, Powder Surface Area and Porosity, 3rd Ed Chapman Hall, New York, 1991 http://nano.materials.drexel.edu Gas Sorption: Isotherm TypeⅢl Convex to the p/p. axis Exhibited by nonporous solids P/PO TypeⅣ Exhibited by mesoporous solids >Initial part of the type IV follows the same path as the type ll Lowell J. E Shields, Powder Surface Area and Porosity, 3rd Ed. PIPO Chapman Hall, New York, 199111 http://nano.materials.drexel.edu Gas Sorption: Isotherm Va P/Po 1 Type I or Langmuir S. Lowell & J. E. Shields, Powder Surface Area and Porosity, 3rd Ed. Chapman & Hall, New York, 1991 ¾Concave to the P/Po axis ¾Exhibited by microporous solids ( < 2nm ) P/Po 1 Type II ¾Exhibited by nonporous or macroporous solids ( > 50nm ) ¾Unrestricted monolayer-multilayer adsorption ¾Point B indicates the relative pressure at which monolayer coverage is complete B Va http://nano.materials.drexel.edu Gas Sorption: Isotherm Va P/Po 1 Type III ¾Convex to the P/Po axis ¾Exhibited by nonporous solids Va P/Po 1 Type IV ¾Exhibited by mesoporous solids ¾Initial part of the type IV follows the same path as the type II S. Lowell & J. E. Shields, Powder Surface Area and Porosity, 3rd Ed. Chapman & Hall, New York, 1991