A set-up for simultaneous measurement of second harmonic generation and streaming potential and some test applications

摘要: We present a measurement cell that allows simultaneous of second harmonic generation (SHG) and streaming potential (SP) at mineral-water interfaces with flat specimen are suitable for non-linear optical (NLO) studies. The set-up directly yields SHG data the interface interest can also be used to obtain information concerning influence flow on NLO signals from interface. is measured against reference substrate (PTFE). properties this inert independently determined same conditions. With new cell, first time signal SP surfaces have been simultaneously surface. This in turn unambiguously relate two observations identical solution composition. test fluorite sample confirmed previously observed differences under vs. no conditions sum frequency (SFG) investigations. As surface, an ("hydrophobic") OTS covered sapphire-c electrolyte was studied verify zeta-potential measurements cell. For system we obtained combined zeta-potential/SHG vicinity point zero charge, which were found proportional each other as expected. Furthermore, accessible scales effects flow, velocity stopped occurred interfacial water structure. insensitivity surface corroborated by concomitant molecular dynamics simulations. Finally, function pH automated titrations oxidic Different polarization combinations separate titrations, yielded clearly different data, while zeta-potentials exactly reproduced. combination characteristic dipoles perpendicular scaled over pH-range studied, did not. work provides advanced approach investigating liquid/surface interactions play major role our environment. upgraded SFG studies, will allow more detailed studies chemistry structure given interface, but study specific adsorption including kinetics electrokinetics. Such investigations crucial basic understanding many environmental processes aquatic atmospheric systems.