Adsorption on solids - homogeneous/heterogeneous surface definition

**How could we define homogeneous and heterogeneous surfaces (rigorously)?**


It is among my exam questions (but I could not find any definition in my textbook or on the internet).


I would say the homogeneous surface is a surface made of one type of molecule (opposite of the heterogeneous surface). But my knowledge about surfaces is very surface (and I am surprised it is listed as an exam question) so are there any other conditions or is it enough?




Homogeneous surface is the surface where we can (in the context of the scenario, like the purpose and required/available resolution and sensitivity) neglect any surface variability. Otherwise, the surface is heterogeneous.


It is important to say it is relative evaluation. For a set of surfaces, it can reach both extremes like "everything is homogeneous" to "everything is heterogeneous".


A visually homogeneous surface can be considered heterogeneous when evaluated by the enough zooming-in optical or electron microscope.


A visually heterogeneous surface can be considered homogeneous when evaluated from far enough or with low resolution or sensitivity for differences.


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