Related Experiment Video
Updated: Jul 3, 2026
10:01
Thermal Scanning Conductometry (TSC) as a General Method for Studying and Controlling the Phase Behavior of Conductive Physical Gels
Published on: January 23, 2018
Design and performance of a practical variable-temperature scanning tunneling potentiometry system.
1Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA.
The Review of Scientific Instruments
|August 7, 2008
Summary
We developed a scanning tunneling potentiometry system to map electrochemical potential and surface topography simultaneously. This instrument achieves high voltage sensitivity, enabling nanoscale potential mapping with atomic-scale imaging.
Area of Science:
- Surface Science
- Nanotechnology
- Electrochemistry
Background:
- Scanning tunneling microscopy (STM) is crucial for nanoscale surface imaging.
- Measuring electrochemical potential at the nanoscale is challenging.
- Existing techniques lack simultaneous topography and potential mapping capabilities.
Purpose of the Study:
- To construct a novel scanning tunneling potentiometry (STP) system.
- To achieve simultaneous mapping of electrochemical potential and surface topography.
- To push the noise performance of potentiometric measurements to the fundamental limit.
Main Methods:
- Developed a novel sample biasing technique.
- Implemented a continuous current-nulling feedback scheme.
- Integrated STP with angstrom-scale STM imaging.
Main Results:
- Achieved 130 nV voltage sensitivity, resolving potentials at 2 nm scales.
- Maintained angstrom-scale STM imaging capabilities.
- Demonstrated versatility across wide temperature ranges and scan sizes up to 15 microm.
Conclusions:
- The developed STP system offers unprecedented capabilities for nanoscale electrochemical measurements.
- The instrument's performance is limited only by Johnson noise.
- The system's versatility and resolution open new avenues for surface science research.
Related Concept Videos
01:06Potentiometry: Overview
Potentiometry is an analytical technique that measures the potential difference between two electrodes in an electrochemical cell without drawing any significant current that could alter the solution's composition. This method employs an indicator electrode, which exchanges electrons with the analyte solution, and a reference electrode with a constant potential. Each electrode is immersed in a solution comprised of two half-cells. In a conventional setup, the reference electrode serves as the...
01:19Potentiometry: Types of Electrodes
Reference electrodes serve as a stable reference point for potentiometric measurements, while indicator and working electrodes react to variations in the composition of a solution.
The Standard Hydrogen Electrode (SHE) is a widely used reference electrode that maintains zero potential across all temperatures. However, its need for a continuous hydrogen gas supply renders it impractical for everyday use.
An alternative to SHE is the Saturated Calomel Electrode (SCE). This electrode features an...
The Standard Hydrogen Electrode (SHE) is a widely used reference electrode that maintains zero potential across all temperatures. However, its need for a continuous hydrogen gas supply renders it impractical for everyday use.
An alternative to SHE is the Saturated Calomel Electrode (SCE). This electrode features an...
01:15Potentiometry: Membrane Electrodes
Membrane electrodes, also known as p-ion electrodes, use membranes that selectively interact with free analyte ions, generating a potential difference across the membrane. The resulting membrane potential, known as the asymmetry potential, is not zero even when analyte concentrations on both sides of the membrane are equal. The membrane's response is typically not selective to a single analyte but proportional to the concentration of all ions in the sample solution capable of interacting at the...
01:12Voltammetric Techniques: Linear-Scan (E vs Time)
Polarography is a classical voltammetric technique used to analyze electrochemical reactions. This method applies a linear potential sweep to a dropping mercury electrode (DME), and the resulting current is measured. A dropping mercury electrode is commonly used as the working electrode in polarography. It consists of a capillary tube filled with mercury, where the tiny droplet forms at the tip. This droplet continuously drops from the capillary, creating a new electrode surface for each...
01:30Potentiometer
Voltage and current measurements using a standard voltmeter and ammeter alter the circuit being measured either by drawing or resisting the current flow, which introduces uncertainties in the measurements. Null measurements balance the voltages so that no current flows through the measuring device and, therefore, no alterations occur in the measured circuit.
Suppose the emf of a battery needs to be measured. If the battery is directly connected to a standard voltmeter, the measured quantity is...
Suppose the emf of a battery needs to be measured. If the battery is directly connected to a standard voltmeter, the measured quantity is...
01:31Potentiometric Titration: Overview
Potentiometric titration is a quantitative analytical technique that determines the concentration of an analyte by measuring the potential difference between the two electrodes in the solution. The endpoint of a potentiometric titration is the point at which there is a significant change in the potential difference. It occurs when the stoichiometric reaction between the analyte and the titrant is complete. The endpoint is usually determined graphically by plotting the measured potential...