ELSA (Electrochemical Surface and Interface Analysis Cluster)

Central distribution chamber

ELSA will be connected to two electrochemical stations focused on:

• Solid/liquid interface experiments
• Solid-electrolyte-interface (SEI) experiments

Solid/liquid interface experiments: We are preparing an electrochemical (EC) chamber to carry out the quasi in-situ measurements on Solid/liquid interfaces. This chamber will be dedicated to electrolysis, CO₂ reduction, corrosion, and recycling applications. The key component of an electrochemical setup is a cell, and it is well known that the cell designed for operando and in-situ clusters have some limitations. There is a trade off between the easy transfer of the working electrode and the geometry of the cell.

Herein, we are developing a unique three-electrode cell with ideal geometry to minimize the ohmic resistance. In addition to this, we are aiming to remove the organic impurities present in the electrolyte as their deposition at the surface of films complicates the surface/interface phenomena. Further details and images of electrochemical cell will be added soon.

Solid-electrolyte-interface (SEI) experiments: Second electrochemical chamber will be devoted for the cutting-edge research in the field of batteries. Further details will be added soon.

Ultra-High Vacuum (UHV) Kelvin Probe

Kelvin probe is a highly surface sensitive technique used to measure the work function of a material, defined by the maximum top three atomic layers. This technique is similar to  atomic force microscopy (AFM) except being a non-contact technique. ELSA will be equipped with a UHV kelvin probe (Model- UHV KP020, KP Technology) to measure the work function of thin films before and after electrochemical measurements. As this technique is highly surface sensitive, we can determine surface changes (adsorption, surface reconstruction, defects, charge carrier trapping, corrosion etc.) occurring after exposure to electrolyte.

Scanning X-ray Photoelectron Spectroscopy (SXPS)

XPS technique is surface sensitive and used to determine the surface composition limited to the top few nm layer. It is based on the external photoelectric effect; the sample is irradiated with X-rays, which results in the emission of photoelectrons. The kinetic energy of the ejected photoelectrons reveals the elemental composition and electronic state of surface elements. That’s why this technique is also known as electron spectroscopy for chemical analysis (ESCA).

Model: PHI 5000 Versa Probe III SXPS

Specifications:

• Unique high flux X-ray source providing focused monochromatic X-ray (Al anode) beam and micro-area spectroscopy capability
• High resolution 180° spherical capacitor energy analyzer
• Scanning X-ray imaging within 1-5 seconds with fine focusing to 10 µm diameter
• Floating column monatomic argon ion gun
• Dual beam charge neutralization
• Dual Zr/Mg anode
• mu-metal test chamber for magnetic field shielding enhancement
• 20 kV Argon gas cluster ion gun beam (GCIB) with Zalar rotations minimizing the potential for chemical damage
• Reflection Electron Energy Loss Spectroscopy (REELS) allowing spectra acquisition up to 2000 eV in loss energy
• Five axis sample stage with x and y translation of ± 25 mm, z axis translation of ± 20 mm and tilt axis range of 0° to 90°
• 4 electrical contact hot/cold stage
• Large sample introduction chamber
• 60 mm vacuum transfer vessel
• Camera with zoom lens to capture image in introduction chamber
• Intro ion gauge option allows vacuum level measurement up to 10^-8 Pa

SXPS with above-mentioned specifications provides following information:

• Quantitative surface analysis: elemental composition, chemical formula, and electronic state of elements
• Secondary electron image allows to distinguish heterogenous surfaces
• Angle-dependent XPS measurement and compositional depth profiling possible

Applications:

• Thin films and coatings analysis
• Nature of interfacial layers
• Detection of dopants and impurities
• Corrosion study

Sample Requirements:

• Powder/thin film (Organic/inorganic/ Polymer)
• Nature: conducting, semi-conducting, insulating

Auger Spectroscopy (AES)

ELSA will be equipped with AES, which is a complementary surface analysis technique. In AES technique, the sample is irradiated with a focused electron beam leads to the ejection of an inner shell electron. The vacancy of ejected electron is filled by an outer shell electron with emission of secondary X-ray. This secondary X-ray of energy equal to the energy difference between two orbitals leads to the ejection of another outer shell electron known as auger electron. The kinetic energy of auger electron is element specific and helps in evaluating the surface composition. The focused electron beam allows the analysis of ultramicroscopic area (5 nm or less). AES provides better spatial resolution over XPS as its probe beam is relatively 100 times smaller.

Model: Scanning Auger Nanoprobe (PHI 710)

Specifications:

• Most versatile Auger analysis capability owing to the coaxial electron gun and cylindrical analyzer geometry quenching the shadowing effect
• Secondary electron imaging with 4096 by 4096 pixel resolution and fine focussing to ~3 nm.
• Dual beam Charge neutralization allows measurement of non-conducting materials
• Floating column monatomic argon ion gun
• Focused ion beam (FIB)
• 4 electrical contact heating stage
• Flexible five axis sample stage with x and y translation of ± 25 mm, z axis translation of ± 20 mm
• Acoustic enclosure to reduce image drift and mu-metal test chamber for magnetic field shielding enhancement
• 60 mm intro chamber
• Intro ion gauge option allows vacuum level measurement up to 10^-8 Pa

Applications:

• Thin films and coatings analysis
• Nature of interfacial layers (with FIB, it’s easy to investigate the surface and deeper layers at the same time)
• Detection of dopants and impurities
• Corrosion study

Sample Requirements:

• Powder/thin film (Organic/inorganic/ Polymer)
• Nature: conducting, semi-conducting, insulating

Vacuum Suitcase

ELSA will be equipped with a vacuum suitcase (≤ 10^-10 mbar) to integrate the system with other CEST facilities. Therefore, we can transfer the sample from ELSA lab to CEST without exposing the surface to air.