Electrochemical identification of molecules in a scanning probe microscope

A method for producing a topographic image of a surface of a sample including an identification of selected chemical substances present on said sample surface, said method comprising the steps of:

• placing the sample on a conductive backing electrode;
• effecting a topographical scan of the sample surface to produce a map of the surface topology of the sample surface;
• effecting an electrochemical scan of the sample surface with a scanning probe microscope having a scanning probe;
• applying a plurality of bias voltages between said backing electrode and said scanning probe during said electrochemical scan, at least some of said bias voltages causing reduction or oxidation reactions in chemical substances present upon the sample surface;
• measuring current flow between said scanning probe and said backing electrode while scanning the sample surface and associating said current flow with a position of said scanning probe over said sample surface;
• determining for each of said plurality of bias voltages the existence of any relatively high measured current flow and said position of said scanning probe over said sample surface at the time of said relatively high measured current flow to form a datum comprising BIAS VOLTAGE and POSITION;
• looking up in a table of reduction and/or oxidation potentials for each said datum said BIAS VOLTAGE to determine a chemical substance associated therewith;
• and
• displaying an image of the sample surface comprising said map of the surface topology of the sample surface having superimposed thereon for each said datum at said POSITION an indicator of a chemical substance determined by said BIAS VOLTAGE.

An electrochemical scanning probe microscope for determining the existence and location of selected chemical substances on a surface of a sample disposed on a conductive backing electrode, said electrochemical scanning probe microscope comprising:

• a conductive scanning probe tip;
• bias voltage means for applying a plurality of bias voltages between said scanning probe tip and the backing electrode;
• current measuring means for measuring current flow between said scanning probe tip and the backing electrode;
• reaction detection means for determining current flow associated with oxidation or reduction reactions taking place on the sample surface immediately adjacent said scanning probe tip;
• position sensing means for determining a position of said scanning probe tip over the sample surface;
• and
• storage means for recording information indicative of said position and a bias voltage associated with said oxidation or reduction reactions detected by said reaction detecting means.

An electrochemical scanning probe microscope for determining the existence and location of selected chemical substances on a surface of a sample disposed on a conductive backing electrode, said electrochemical scanning probe microscope comprising:

• a conductive scanning probe tip;
• bias voltage means for applying a plurality of bias voltages between said scanning probe tip and the backing electrode;
• current measuring means for measuring current flow between said scanning probe tip and the backing electrode;
• reaction detection means for determining current flow associated with oxidation or reduction reactions taking place on the sample surface immediately adjacent said scanning probe tip;
• position sensing means for determining a position of said scanning probe tip over the sample surface;
• and
• identification means for determining a chemical substance associated with said oxidation or reduction reactions detected by said reaction detection means.