LEIS – M470.
Scanning probe electrochemistry technique which measures impedance with spatial resolution
Used extensively for research in coatings and corrosion. LEIS is of particular use for measuring the impedance of coated samples.
Localized Electrochemical Impedance Spectroscopy is performed on BioLogic’s modular M470 system with the LEIS470 option.
Localized Electrochemical Impedance Spectroscopy (LEIS) is a scanning probe electrochemistry technique that measures electrochemical impedance with spatial resolution. The LEIS measurement is based on bulk Electrochemical Impedance Spectroscopy (EIS) in which impedance is measured as a function of applied frequency. In LEIS the bi-electrode probe is used to measure the local ac current flowing in an electrolyte above a biased sample. When LEIS is run on the M470 researchers can perform both stationary local EIS measurements and scanning measurements in which the impedance is mapped at a single frequency. These scanning measurements are sometimes referred to as Localized Electrochemical Impedance Mapping (LEIM).
LEIS has been used extensively in coatings and corrosion research. Using LEIS a wide variety of pure and alloyed metal systems have been investigated. The effectiveness of different coatings for corrosion protection, as well as the abilities of different smart coatings, has been investigated with LEIS. Outside of the field of corrosion, LEIS is finding use in the research of battery electrodes to compare different battery compositions and different states of charge.
LEIS measurement of 200 µm gold Point in Space in water.
Overview: Discover the local impedance of your sample
- Local impedance sweeps and maps
- Fully integrated system
Measure coated or uncoated samples
LEIS has widespread use in studying the effectiveness of coatings to protect the underlying metal. Even though the sample acts as the working electrode in LEIS studies, it is possible to measure samples even when the sample has poor electrochemical activity, such as coated samples. This is possible because the nature of the LEIS experiment means it can be tuned by changing the ac frequency applied during the measurement. Using a low frequency, LEIS can be used to map the local impedance of uncoated conductive samples. If a coated sample is to be measured, however, this is possible by using a high measurement frequency.
Measurement of sample response without the influence of the probe
LEIS is a five electrode experimental setup. The sample, reference, and counter form a traditional three electrode cell at which the EIS measurement is carried out. The probe is a bi-electrode which is separate from the cell of interest, and instead only monitors this cell. Because the bi-electrode probe is not directly involved in the three-electrode cell it does not influence the processes occurring here. Therefore, the measured impedance is not a distortion of the interaction between the probe and sample, but instead it is a direct reflection of the impedance of the sample.
The Scanning Electrochemical Workstation software provides unique capabilities and interactivity in support of the Model 370 and Model 470 nanometer-resolution scanning probe microscopes. This highly ergonomic software has been designed to facilitate and improve the user experience and render workflows more efficient:
- Improved data analysis, manipulation, and interactivity
- Automatic measurement and sequencing functionalities.
Over 40 discrete experiments provided throughout, each with their own individual variations
M470 Scanning Electrochemical Workstation Software
MIRA: Microscopic Image Rapid Analysis
|Scan Range (x,y,z)||110 mm x 110 mm x 110 mm|
|Minimal Step Size (x,y,z)||20 nm|
|Positioning||Closed loop positioning, linear, zero hysteresis encoder with direct real-time readout of displacement in x, y, z|
|Linear position encoder resolution||20 nm|
|Max Scan Speed||10 mm/s|
|Measurement Resolution||32-bit decoder @ up to 40 MHz|
|Dimensions||500 mm (H) x 400 mm (W) x 675 mm (D)|
|Compliance Voltage||±12 V|
|Applied Potential||±10 V|
|Measured Potential||±10 V|
|Current Ranges||100 pA to 1A|
|Maximum Current||± 500 mA|
|Current Resolution||76 aA|
|Floating Capability||Floating Mode|
|Cell Connections||2, 3, or 4 electrode|
|Scan Rate||1 µV/s to 200 V/s|
|Modes||Potentiostat, Galvanostat, OCP|
|Frequency Range||10 µHz to 3 MHz|
|Analyzer Accuracy||1%, 1°|
|Frequency Resolution||0.1 nHz|
|Impedance||1013 Ω || 7 pF typical|
|Bias Current||1 pA typical|
|Available Experiments||LEIS Frequency Sweep, Line Scan, Area Scan|