https://doi.org/10.1351/goldbook.14037
Number of entities (atoms, molecules or ions) photoadsorbed per regular surface site at a uniformly irradiated surface of an adsorbent.
Notes:
- Mathematical expression: \(\theta_{\rm{ph}} = N/N^{\rm{ss}}\) with \(N\) the number of entities photoadsorbed and \(N^{\rm{ss}}\) the number of surface sites (mainly regular surface sites, i.e., regular lattice ions or atoms; typically, \(N^{\rm{ss}}\) ca. \(\pu{E15 cm-2}\)). \(\theta_{\rm{ph}}\) is a quantity of dimension one (it is a fractional number).
- \(\theta_{\rm{ph}}\) has been called photoadsorption number; fraction is preferred. It should not be called capacity, since the term capacity should be reserved for the maximal adsorption number.
- The photoadsorption fraction, \(\theta_{\rm{ph}}\), is smaller than the photoadsorption capacity, \(\theta_{\rm{max}}\) (i.e., \(\theta_{\rm{ph}} \lt \theta_{\rm{max}}\)).