1.
J Am Chem Soc
; 127(6): 1632-3, 2005 Feb 16.
Article
in English
| MEDLINE
| ID: mdl-15700985
ABSTRACT
Tethering a pH-sensitive dye to a silica surface enables the interfacial pH to be measured optically and is found to be 2 pH units lower than that of the bulk. The positive H+ ions are attracted by the surface potential and have an enhanced concentration consistent with the previously determined surface potential of order -120 mV, with respect to zero in the bulk. A stable near-surface charged layer once formed is not disrupted by the bulk pH.