03085 IUPAC Gold Book - interfacial layer 10.1351/goldbook.I03085 I03085 current synonyms: interfacial region, interphase 1 The inhomogeneous space region intermediate between two bulk phases in contact, and where properties are significantly different from, but related to, the properties of the bulk phases. Examples of such properties are: compositions, molecular density, orientation or conformation, charge density, pressure tensor, electron density, etc. The interfacial properties vary in the direction normal to the surface. Complex profiles of interfacial properties occur in the case of multicomponent systems with coexisting bulk phases where attractive/repulsive molecular interactions involve adsorption or depletion of one or several components. This interfacial region may also be regarded as a distinct, though not autonomous, phase and be called the interphase. charge density https://goldbook.iupac.org//terms/view/C00988 conformation https://goldbook.iupac.org//terms/view/C01258 electron density https://goldbook.iupac.org//terms/view/E01986 interfacial region https://goldbook.iupac.org//terms/view/I03087 interphase https://goldbook.iupac.org//terms/view/I03118 PAC, 1986, 58, 437. 'Interphases in systems of conducting phases (Recommendations 1985)' on page 439 (https://doi.org/10.1351/pac198658030437) PAC, 1994, 66, 1667. 'Thin films including layers: terminology in relation to their preparation and characterization (IUPAC Recommendations 1994)' on page 1673 (https://doi.org/10.1351/pac199466081667) https://goldbook.iupac.org/terms/view/I03085/html https://goldbook.iupac.org/terms/view/I03085/json https://goldbook.iupac.org/terms/view/I03085/plain Citation: 'interfacial layer' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.I03085 The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using. 2026-04-21T12:09:10+00:00