Interfacial pH at an isolated silica-water surface.
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.
O'Reilly
Josephine P
JP
School of Biological and Chemical Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.
Butts
Craig P
CP
l'Anson
Ian A
IA
Shaw
Andrew M
AM