Scanning microscope with Kelvin probe VS-SKP

The Kelvin probe experiment uses a non-destructive method to determine the relative difference in the work function between the probe and the sample. The work function describes the energy required to release an electron from the surface of a conductor; electrochemists often interpret this as the difference between the Fermi level of an electrode, the average energy of the electrons, and that of the vacuum.
 

A metal microprobe is placed close to the surface of the sample (on the order of 100 microns). If the microprobe and the sample are made of different metals, there is an energy difference between their electrons._cc781905 -5cde-3194-bb3b-136bad5cf58d_Then, the microprobe is electrically connected to the sample, through the system's internal electronics. As a consequence, one metal forms a positive charge on its surface and the other metal forms a negative charge on its surface. The probe and the sample are separated by a dielectric (air), so a capacitor is formed. Then, the The probe is vibrated and then a sufficient "backing potential" or "nulling potential" is applied to minimize this capacitance. With the voltage applied that causes the capacitance to go to zero, the original state. This value is recorded and graphed.
 

Experiments are generally performed in gaseous ambient conditions, but several published examples use humidified environments. An organic coating or paint can be applied to the underlying conductive sample.
 

This relative work function can also be correlated with a value of Ecorr.
 

Our SKP is also capable of operating in Survey Mode. Without changing connections or probe, a reference voltage is applied to the sample. This reference voltage makes the surface of the sample is uniform. The change in capacitance is then from a changing plate spacing (via the equation of a capacitor).
 

This information can be used in 2 ways: Place the probe at a known distance from the sample, using a calibration coefficient.
 

Map topography for later use in SKP constant distance mode. This is particularly useful for studying welds or other samples of complex topography. 

 

• Measures the relative work function between the probe and the sample.
• You can correlate the work function with the corrosion potential (Ecorr). 
• Able to perform experiments in survey mode to measure and set the distance between the probe and the sample
• You can perform constant distance operation together with survey mode experiments, using the same probe.