Title: photoadsorption capacity
Long Title: IUPAC Gold Book - photoadsorption capacity
DOI: 10.1351/goldbook.14034
Status: current

Definition
Maximal number of entities (molecules, atoms, or ions) per regular surface site that can be photoadsorbed at a uniformly irradiated surface of an adsorbent, \(\theta_{\rm{max}} = N_{\rm{max}}/N^{\rm{ss}}\) where \(N_{\rm{max}}\) is the maximal number of entities photoadsorbed and \(N^{\rm{ss}}\) is the number of surface sites (mainly regular surface sites, i.e., regular lattice ions or atoms; typically, \(N^{\rm{ss}}\) ca. \(\pu{E15 cm-2}\)).

Notes
1) \(\theta_{\rm{max}}\) is a quantity of dimension one (a fractional number). \(\theta_{\rm{max}}\) is about \(\pu{E-5 - E-3}\).
2) This term has been often called maximal photoadsorption capacity. This denomination is redundant, because capacity already refers to the maximal possible value of a property.

Related Terms
- dynamic photoadsorption process: https://goldbook.iupac.org//terms/view/14006
- photoadsorbed: https://goldbook.iupac.org//terms/view/14032
- photoadsorption fraction: https://goldbook.iupac.org//terms/view/14037
- regular surface site: https://goldbook.iupac.org//terms/view/14083
- turnover number: https://goldbook.iupac.org//terms/view/14101

Source
- PAC, 2011, 83, 931. 'Glossary of terms used in photocatalysis and radiation catalysis (IUPAC Recommendations 2011)' on page 964 (https://doi.org/10.1351/PAC-REC-09-09-36)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/14034/html
- json: https://goldbook.iupac.org/terms/view/14034/json
- xml: https://goldbook.iupac.org/terms/view/14034/xml

Citation: Citation: 'photoadsorption capacity' 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.14034
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Accessed: 2026-06-30T10:26:47+00:00