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# Kratos Analytical

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## Pages
- [Thank You-continuing contact](https://www.kratos.com/continuing-contact-from-kratos/)
- [News & Events](https://www.kratos.com/about-us/news-events-2/): Learn about Kratos Analytical's recent developments and announcements.
- [Meetings & Exhibitions 2026](https://www.kratos.com/about-us/news-events/): At Kratos we sell our instruments through the science they can achieve. We actively collaborate with material scientists characterising novel materials. Where possible, we will present at conferences and in peer-reviewed journals.
- [FAQ](https://www.kratos.com/faq/): Like many scientific disciplines, surface analysis can be confusing. Here we attempt to answer some of the frequently asked questions relating to XPS and surface analysis.
- [Catalysis & Petrochemicals](https://www.kratos.com/surface-analysis-application-areas/catalysis-petrochemicals/): X-ray Photoelectron Spectroscopy (XPS) has emerged as a pivotal tool in the field of catalysis research, offering unparalleled capabilities for probing the surface composition, chemical state, and electronic structure of catalysis materials.
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- [Electronics & Semiconductors](https://www.kratos.com/surface-analysis-application-areas/electronics-semiconductors/): X-ray photoelectron spectroscopy (XPS) serves as a versatile tool for the analysis of electronic and semiconductor materials, offering crucial insights into their surface chemistry, composition, and electronic structure.
- [Polymers](https://www.kratos.com/surface-analysis-application-areas/polymers/): X-ray photoelectron spectroscopy is ideally suited to the surface characterisation of these polymers as it can provide quantitative chemical state information from the upper 10nm of the material.
- [Biomaterials](https://www.kratos.com/surface-analysis-application-areas/biomaterials/): Biomaterials are those materials which interact with the native-tissue, organ or function in a body. XPS has emerged as a useful technique, offering insights into the composition, chemical state, and bonding characteristics of biomaterial surfaces.
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- [Our Company](https://www.kratos.com/about-us/our-company/): Kratos Analytical employs over 200 staff at our UK headquarters. We also have offices in Frankfurt, Germany and New York, North America.
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- [Hard X-ray Photoelectron Spectroscopy (HAXPES)](https://www.kratos.com/techniques/hard-x-ray-photoelectron-spectroscopy-haxpes/): When using higher energy Ag Lα X-rays (2984.3 eV) for photoemission excitation the technique is referred to as HAXPES.
- [Auger Electron Spectroscopy (AES)](https://www.kratos.com/techniques/auger-electron-spectroscopy-aes/): AES is a technique complementary to X-ray photoelectron spectroscopy, but has the advantage of much better lateral resolution.
- [Inverse Photoemission Spectroscopy (IPES)](https://www.kratos.com/techniques/inverse-photoemission-spectroscopy-ipes/): IPES is the opposite of XPS. It relies on incident low energy electrons interacting with a material’s unoccupied orbitals in the conduction band.
- [Reflected Electron Energy Loss Spectroscopy (REELS)](https://www.kratos.com/techniques/reflected-electron-energy-loss-spectroscopy-reels/): REELS can be used to determine electronic band gaps and the relative energy levels of unoccupied molecular orbitals.
- [Ultraviolet Photoelectron Spectroscopy (UPS)](https://www.kratos.com/techniques/ultraviolet-photoelectron-spectroscopy-ups/): UPS is analogous to XPS but the excitation source is a helium discharge lamp. It can provide details relating to the electronic structure on a molecular level.
- [Techniques](https://www.kratos.com/techniques/): The AXIS Supra+ capabilities can be further enhanced by adding complementary analytical techniques.  Outlined below are the commonly used surface analysis techniques supported on our AXIS spectrometers.
- [2D & Nanomaterials](https://www.kratos.com/surface-analysis-application-areas/2d-nanomaterials/): These materials, which are essentially one or two atoms thick, exhibit unique and extraordinary properties that make them promising candidates for various applications, such as electronics, optoelectronics, and energy storage. X-ray photoelectron spectroscopy (XPS) offers valuable information about the electronic structure and chemical composition.
- [Thin Films & Coatings](https://www.kratos.com/surface-analysis-application-areas/thinfilm-coatings/): Thin films and coatings play a pivotal role in a diverse range of industries, including electronics, optics, and materials science. Understanding the chemical composition of these films is crucial for optimising their performance and ensuring their desired functionalities.
- [Batteries & Power Storage](https://www.kratos.com/surface-analysis-application-areas/batteries-and-power-storage/): X-ray photoelectron spectroscopy (XPS) is ideally suited to provide information relating to interfacial material properties that are critical to the performance of modern batteries. AXIS spectrometers allow studies of battery materials to be extended to in-situ and in-operando characterisation of model devices.
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- [X-ray Photoelectron Spectroscopy (XPS)](https://www.kratos.com/techniques/x-ray-photoelectron-spectroscopy-xps/): XPS is a surface analysis technique which provides elemental and chemical state information from the uppermost 10nm of a material.
- [Adhesion](https://www.kratos.com/surface-analysis-application-areas/adhesion/): Surface analysis plays a crucial role in understanding and improving the adhesion properties of materials
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- [About Us](https://www.kratos.com/about-us/): Kratos Analytical Limited is a wholly owned subsidiary of Shimadzu Corporation. Our headquarters are in Trafford Park, Manchester, UK
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Techniques X-ray Photoelectron Spectroscopy (XPS) Hard X-ray Photoelectron Spectroscopy (HAXPES) Ultraviolet Photoelectron Spectroscopy (UPS) Inverse Photoemission Spectroscopy (IPES) Reflected Electron Energy Loss Spectroscopy (REELS) Auger Electron Spectroscopy (AES) Thank You
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- [Application Areas](https://www.kratos.com/surface-analysis-application-areas/): Surface analysis provides valuable insight into surface chemistry of a wide range of materials across many application areas.
- [Contact Us](https://www.kratos.com/contact-us/): You can contact us using an online form, telephone or e-mail.
- [Resources](https://www.kratos.com/resources/): Here you can find technical content relating to Kratos XPS instruments and accessories.

## Products
- [VCIS](https://www.kratos.com/product/vcis/): The VCIS designed to produce a stable, high current, monatomic Ar+ ion beam and Ar cluster ions. It is ideally suited to sputter cleaning and depth profiling all types of materials. VCIS may also be used to generate low energy He+ ions for use with ion scattering spectroscopy (ISS).
- [Minibeam 4: Monatomic Ar+ Ion Source](https://www.kratos.com/product/minibeam-4-monatomic-ar-ion-source/): The Minibeam 4 is designed to produce a stable, high current, monatomic Ar+ ion beam with energies from 0.5 to 4 keV. It is ideally suited to sputter cleaning and depth profiling inorganic and metallic films. It may also be used to generate low energy He+ ions for use with ion scattering spectroscopy (ISS).
- [Minibeam 6: Gas Cluster Ion Source (GCIS)](https://www.kratos.com/product/minibeam-6-gas-cluster-ion-source-gcis/): This multi-mode gas cluster ion source is designed to operate in both Arn+ cluster and Ar+ monatomic modes making it suitable for sputter cleaning and depth profiling organic, inorganic and metallic thin films. In addition it may also be used to generate low energy He+ ions for use with ion scattering spectroscopy (ISS).
- [ESCApe data system](https://www.kratos.com/product/escape-software-versatile-automation/): The ESCApe data system encompasses instrument control, data acquisition and data processing in a single, easy to use package. With a user-friendly interface and advanced features, our software streamlines the analytical process, saving you time and maximising efficiency. It’s the latest generation of software for use with AXIS Supra+ and AXIS Nova photoelectron spectrometers.
- [AXIS Supra+ : XPS Surface Analysis Instrument](https://www.kratos.com/product/axis-supra-xps-surface-analysis-instrument/): Market leading, high performance X-ray photoelectron spectrometer. Made to measure for the most demanding materials characterisation applications.

## Application Notes
- [Imaging and selected area XPS analysis of crisp packaging multilayer material](https://www.kratos.com/application-note/xps-of-laminated-thin-films/): XPS enables the identification of elemental constituents and their chemical states within the top few nanometers of each layer, offering insights into adhesion quality, barrier performance, and degradation mechanisms. 
- [Benefits of cryo-XPS for battery materials analysis](https://www.kratos.com/application-note/benefits-of-cryo-xps-for-battery-analysis/): The benefit of cryo-cooling for analysis of battery materials is demonstrated for the analysis of lithium-sulphur battery material.
- [Gas cluster sputter depth profiling of cross-linked plasma polymers](https://www.kratos.com/application-note/gas-cluster-sputter-depth-profiling-of-cross-linked-plasma-polymers/): New ion sources such as the multi-mode Ar gas cluster ion source (GCIS) offered by Kratos have revolutionised the study of organic thin films by depth profiling.
- [Spatial characterisation of immobilised biomolecules on surfaces](https://www.kratos.com/application-note/xps-of-biomolecules-on-surfaces/): Analysis of biomolecules on surfaces is essential to various applications of biosensors and biomolecule engineering. Matrix-assisted laser desorption/ionisation (MALDI) is now an established technique for mass spectrometry of biomolecules. Different matrix-analyte preparation protocols have been shown to influence the desorption or ablation process resulting in either high or low metastable fragmentation. It has been speculated that following laser ablation the velocities of the analyte and matrix can be regarded as a valuable and meaningful characteristic of the MALDI process. However, the interaction and distribution of the analyte with respect to the matrix is poorly understood. Here we study the distribution of a selection of biomolecules as a function of matrix material using high resolution imaging X-ray photoelectron spectroscopy (XPS).
- [Sample cleaning using Ar-GCIS](https://www.kratos.com/application-note/sample-cleaning-using-ar-gcis/): Ar-GCIS as an effective tool for surface cleaningTypical samples are often presented for analysis following transportation in a less than ideal environment. This results in an analysis and measured surface composition that is not representative of the true surface of the original material.There are a limited number of methodologies available that can effectively clean the sample and restore the original surface without inducing some additional chemical changes and thereby changing the very surface that is being investigated. The development of Ar-gas cluster ion source has changed this.
- [Oxidation of cobalt hydroxide](https://www.kratos.com/application-note/oxidation-of-cobalt-hydroxide/): The Catalysis Cell is used to study the oxidation of cobalt hydroxide in a pressurised oxygen environment.
- [Reduction in preferential sputtering of TiO2](https://www.kratos.com/application-note/reduction-in-preferential-sputtering/): Monatomic Ar ions of beam energy 5 kV cause considerable changes to the structure of amorphous Titania resulting in the preferential removal of oxygen and damage to the lattice structure. Titanium is reduced from the +4 oxidation state to +3 and +2 oxidation state during this preferential removal. In contrast, the use of Ar clusters leads to significant reduction in preferential sputtering, greatly diminishing this damage. It also reduces the incorporation of the impinging ion into the sample surface. Here we discuss the use of high energy Arn clusters as a methodology for reducing the damaging effects caused by monatomic ion bombardment.
- [XPS of medical textiles](https://www.kratos.com/application-note/xps-of-medical-textiles/): XPS of medical textiles to study anti-adhesive coatingsXPS is a well-established method for the chemical characterisation of material surfaces. Key developments in recent years, including imaging, have resulted in a wider range of applications. Manufacturers and suppliers of both commercial and technical textiles are now exploiting XPS as an ideal tool to aid the development and optimisation of the types of surface coating/treatment demanded by industry and consumers.
- [Analysis of Ni/Co/Mn alloy using an automated monochromatic Ag Lα X-ray source](https://www.kratos.com/application-note/analysis-of-ni-co-mn-alloy-using-an-automated-monochromatic-ag-l%ce%b1-x-rays-source/): Overlapping photoelectron lines and Auger features are a common problem in analysis of complex materials. The standard approach of switching to an achromatic Mg X-ray source is sometimes undesirable due to the introduction of X-ray satellites into the spectrum. In this example we show how Kratos’ automatic monochromatic Ag Lα X-ray source may be used to excite a satellite free spectrum and allow unambiguous determine the oxidation state of a Ni/Co/Mn alloy.
- [Quantified imaging of silicon dioxide particles](https://www.kratos.com/application-note/quantified-imaging-of-silicon-dioxide-particles/): In this applications note, we demonstrate the AXIS Supra+ capability of generating quantified imaging of silicon dioxide particles dispersed on the surface of a silicon wafer.
- [XPS analysis of an ionic liquid](https://www.kratos.com/application-note/xps-analysis-of-an-ionic-liquid/): An AXIS spectrometer was used to probe the surface chemistry of a widely used ionic liquid. The elemental surface composition was analysed and information was gained regarding the various chemical environments of the surface elements. Traditional surface analysis techniques such as ARXPS were exploited to determine the orientation of the mobile molecules in the uppermost layer of the liquid. Thestability of the liquids under X-ray irradiation was also investigated.
- [Smart phone screen – depth analysis of alkali and alkali earth metals](https://www.kratos.com/application-note/smart-phone-screen-depth-analysis-of-alkali-and-alkali-earth-metals/): Depth analysis beyond the 10 nm sampling depth of XPS is achieved by destructive, sputter depth profiling. In this study we apply the technique of depth profiling to analyse the concentration of elements in the near surface region of smart-phone display glass. We will look at the distribution of alkali and alkali earth metals - in particular K which is a key element in the glass toughening process. Two different depth profiling methods were used, monatomic Ar+ and Arn+ cluster, and a comparison is made regarding the ion bombardment effects of these two methods.  We emphasise the importance of ion choice when depth profiling inorganic materials in particular those containing light alkali metals.
- [Surface chemistry of plasma coated textiles studied by XPS](https://www.kratos.com/application-note/plasma-coated-textiles-xps-study/): Plasma coated textiles exhibit properties which are beneficial to the wearer, including water repellency . The performance of fluorinated textile treatment methods, in terms of wash resistance, was evaluated by XPS. Two different fluorination methods, solution based treatment and plasma polymer deposition, and four different textiles were studied with a view to producing long lasting, high performance clothing systems for outdoor activities. An important attribute of such textiles is the ability of the surface of the material to retain or regain its liquid repellent nature following conventional washing cycles.XPS analysis revealed the degree of surface fluorination before and after wash cycles enabling the durability of the thin film coatings to be evaluated. Results indicated that for most materials the plasma polymer coated textiles exhibited better performance in terms of fluorine coverage and retention than the solution based fluorination method.
- [Investigating the surface and interface of Li ion thin-film battery materials](https://www.kratos.com/application-note/investigating-the-surface-and-interface-of-li-ion-thin-film-battery-materials/): Here we use conventional surface analysis techniques of XPS and sputter depth profiling to understand the surface and bulk chemistry of Li ion thin-film materials. LiPON films formed via atomic-layer deposition (ALD).  Comparisons are made between the results obtained from conventional monatomic depth profiling and cluster depth profiling.
- [Combined Argon cluster UPS-XPS depth profile of OLED thin-film](https://www.kratos.com/application-note/combined-argon-cluster-ups-xps-depth-profile-of-oled-thin-film/): Combined Argon cluster UPS-XPS depth profile of OLED thin-film deposited on Indium-doped Tin oxide is presented in this applications note. XPS and UPS spectra were acquired after each etching cycle. Compositional changes were seen through the film and at the interface with the substrate. Changes in UPS spectra were directly compared to changes in compositional change.
- [Analysis of drug coated polymer stents studied by XPS](https://www.kratos.com/application-note/polymer-stents-studied-by-xps/): Cardiovascular interventional therapy with stents has emerged as the most effective method for coronary heart disease. However, thrombosis and hyperplasia are the usual pathological responses to the implantation of foreign devices. To suppress this immune response and that of overgrowth and subsequent restenosis anti-inflammatory drugs are now loaded onto the surface of stent implants. Here we investigate the surface of drug loaded polymer stents. The stents are made of polylactic acid (PLA) dosed with an anti-inflammatory drug with a molecular structure of C51HxNO13. Polymer stents studied by XPS yields quantitative information regarding drug distribution. Using Argon cluster sputtering we can see the distribution of the drug into the stent structure. Analysis is also performed on stents submerged in buffer solution (PBS) to see the effects on ageing and the propensity for the drug to migrate into the solution with time.
- [Quantification of layer composition in compound semiconductors](https://www.kratos.com/application-note/quantification-of-layer-composition-in-compound-semiconductors/): Compound semiconductors are the key underpinning technology in optoelectronics, and also used in electronic applications with specialist requirements (e.g. power). The ability to engineer the electronic and optical properties of compound semiconductor alloys, for example in terms of their alloy composition, which may be binary, ternary, quaternary or quinary, and grow multiple layers of different semiconductor alloys on top of each other (heterostructures), is a key part of their success.
- [XPS analysis of frozen 1,4-dibromobenzene](https://www.kratos.com/application-note/xps-analysis-of-frozen-14-dibromobenzene/): The molecule 1,4-dibromobenzene is of interest as a precursor for the synthesis of conjugated polymers with applications in nanoelectronic and electronic devices. 1,4-dibromobenzene has a vapour pressure of 0.0575 mmHg at 25˚C such that it will volatilise in vacuum at room temperature. To achieve XPS characterisation this organic material requires cooling to < -100˚C before pumping and introduction to the analysis chamber.
- [Surface analysis of strip coated materials pre- and post- ‘cleaning’](https://www.kratos.com/application-note/surface-analysis-of-strip-coated-materials-pre-and-post-cleaning/): Strip coated materials are commonly used in optic applications for the removal of grease and small particulates form the surfaces of delicate materials. Typically these include mask gratings, laser optics, telescope lenses and refractors. A clear red solution consisting of a blend of polymers is applied using a small brush and is then left to set. Once set, the polymer coating is peeled away leaving a pristine surface free of particulates. In this applications note we use the AXIS photoelectron spectrometer to perform surface analysis of strip coated materials pre- and post- 'cleaning' with interesting results.
- [Distribution, segregation and chemical state identification of Lithium salts on Cu electrodes](https://www.kratos.com/application-note/xps-of-lithium-salts-on-cu-electrodes/): XPS of lithium salts : Rechargeable metal-based batteries (Li, Na and Al) are among the most versatile platforms for high-energy storage. Unfortunately however there are several pitfalls for these energy storage systems, one of which is deposition and dendrite formation during repeated cycles of charge and discharge. Many studies have been performed in search of a dendrite-free, deposition-free system for lithium batteries using novel materials such as 3D structures and carbon nanofibers. Here we will explore the distribution of Lithium in different chemical environments on electrode surfaces. We employ conventional surface analysis techniques (XPS) to yield large area, quantitative, information regarding the distribution of surface species. To explore the lateral and depth distribution of Li we also utilise X-ray photoelectron imaging and Argon cluster depth profiling.
- [Reconstructed concentration depth profiles from angle-resolved XPS using MEM software](https://www.kratos.com/application-note/reconstructed-concentration-depth-profiles-from-angle-resolved-xps-using-mem-software/): XPS was used to characterize the surface chemistry of layered thin film materials, using monochromated Al Kα (1486.6 eV) X-rays to gain quantitative chemical information from the uppermost 10 nm of the surface. In this study, we illustrate how ARXPS is used as a more surface sensitive approach to probe only the topmost 1-3 nm of a material, and how one can utilize Maximum Entropy Method (MEM) software to recreate a concentration depth profile from the resulting data. How the removal of contamination effects the resulting MEM model fit is also explored following gentle sputter cleaning using the GCIS.
- [Group array analysis of a combinatorial thin film system](https://www.kratos.com/application-note/group-array-analysis-of-a-combinatorial-thin-film-system/): The last few decades have seen rapid development in computational and theoretical tools for fabricating, simulating, and characterizing material systems. In this applications note the potential of surface characterization by X-ray photoelectron spectroscopy to provide rapid elemental and chemical state information is presented. The development of the group analysis array functionality is of significant importance in the application of XPS analysis to combinatorial materials discovery to allow the processing and display of large data sets. As will be demonstrated, group array analysis provides a more detailed understanding of the chemical distribution across the sample.
- [XPS and UPS characterization of a hybrid PbBr perovskite material with work function measurement](https://www.kratos.com/application-note/xps-and-ups-characterization-of-a-hybrid-pbbr-perovskite-material-with-work-function-measurement/): Ultraviolet photoemission spectroscopy of (semi)conducting samples allows the measurement of the work function of a material. Combined with XPS, this is a powerful combination of techniques to gain information about the valence structure of the surface. Here, a thin film, hybrid organic-inorganic lead bromide perovskite is analysed using a Kratos AXIS spectrometer. A comparison of the data is made after the removal of adventitious carbon with the Gas Cluster Ion Source (GCIS) to interpret how the work function of the material is affected.
- [Valence-level photoelectron spectroscopy of MoS2](https://www.kratos.com/application-note/valence-level-photoelectron-spectroscopy-of-mos2/): Valence level photoelectron spectroscopy (VLPS) was acquired for the material MoS2 using soft X-ray and deep UV photon energies. Spectra were acquired for both as-received and Argon cluster cleaned surfaces.
- [Sample rotation during depth profiling](https://www.kratos.com/application-note/sample-rotation-during-depth-profiling/): The aim of this investigation was to characterise the performance of the gas-cluster ion source (GCIS) for the depth profiling of thick organic multi-layer materials. The sample is composed of 25 repeating units of polystyrene (PS) and polyvinylpyrrolidine (PVP) PS = 288 ± 1.3 and PVP = 328 ± 7 nm on a glass substrate. It has been considered challenging to depth profile thick samples (>1 micron) of soft materials due to the changes which occur under sus-tained X-ray irradiation and bombardment of charged projectiles, however, in this study we describe a methodology to eliminate these issues. The use of fast acquisition, snapshot spectroscopy and sample rotation during etching is presented.
- [Eliminating core line/Auger peak overlap using different photon energies](https://www.kratos.com/application-note/eliminating-core-line-auger-peak-overlap-using-different-photon-energies/): GaN is one of many materials which are difficult to analyze with the conventional Al Kα X-ray source due to a strong overlap between the N 1s core line and the Ga LMM Auger series. This brings difficulties with accurate quantification and also chemical state assignment. In this applications note, GaN was analyzed using different X-ray excitation sources with the aim of shifting the binding energy position of the Ga LMM Auger series to prevent its interference with the N 1s region. Automation of changing between the Al Kα and Ag Lα excitation sources when using the Kratos AXIS Supra+ is an added benefit.
- [A complimentary spectroscopic characterization of a corroded tinplate sample with XPS and AES](https://www.kratos.com/application-note/characterization-of-a-corroded-tinplate-sample-with-xps-and-aes/): A corroded tinplate sample was analysed by XPS and AES techniques using the Kratos AXIS Supra+ to gain an insight into the extent and mechanism of corrosion. XPS was firstly used to analyse the composition of the surface and from this, characterize the Sn 3d and Fe 2p oxidation states. The corroded area was then examined using SEM to pinpoint significant positions for further analysis with AES. The resulting data indicates the position at which corrosion is initiated and examines the extent of this corrosion across an area of the surface.
- [Building the energy level diagram of a 2D material using coincident UPS and IPES](https://www.kratos.com/application-note/building-the-energy-level-diagram-of-a-2d-material-using-coincident-ups-and-ipes/): MoS2 studied using UPS and IPES.
- [Graphene — macro/microscopic imaging and thickness metrology](https://www.kratos.com/application-note/graphene-imaging-and-thickness-metrology/): Graphene flakes prepared and deposited on SiO2 were analysed using X-ray Photoelectron Imaging. Small-spot spectroscopy allowed for thickness measurements to be determined for individual flakes. This method allowed for the metrological determination of layer number.
- [XPS analysis of a N-doped GaAs thin film using Ag Lα excitation](https://www.kratos.com/application-note/xps-analysis-of-a-n-doped-gaas-thin-film-using-ag-l%ce%b1-excitation/): Nitrogen-doped GaAs (GaAs1-xNx) is finding application in high efficiency solar cells and vertical cavity surface emitting lasers (VCSELs). Nitrogen doping has been shown to cause perturbation of the host band structure. Determination of chemical state and nitrogen concentration is pivotal in defining the material’s electronic structure. X-ray photoelectron spectroscopy (XPS) is a commonly used technique for surface characterisation of this dilute N doped material.
- [High-throughput XPS Analysis of Na-Fe-Mn-O Cathodes for Na-ion Batteries](https://www.kratos.com/application-note/xps-analysis-of-na-ion-cathodes/): This applications note highlights materials characterisation of sodium-based cathodic materials studied using high-throughput XPS (X-ray photoelectron spectroscopy). Na-ion batteries are considered to be environmentally favourable alternatives to Li-ion batteries, particularly in the extremely large-scale application of grid storage, given the abundance of Na. Among them, sodium layered oxides are very important cathode materials with good sodium mobility and high specific capacity. Layered transition metal oxides NaXMeO2 consist of layers of MeO6 octahedra to preserve 2D transport channels for direct Na ion diffusion. For metal selections, Me can be Fe, Mn, Co, Cr, Ni, Ti, V and their combinations. Interestingly, single transition metal oxides show worse battery performance than binary or ternary transition metal systems, making composition studies imperative.
- [XPS analysis of SEI layer formed on a lithium-ion battery negative electrode](https://www.kratos.com/application-note/xps-of-sei-layer-on-anode/): This applications note demonstrates the use of both conventional (Al Kα) and higher photon energy (Ag Lα) excited X-ray Photoelectron Spectroscopy (XPS) to characterise the solid electrolyte interphase (SEI) layer formed on a graphite anode during charge/discharge cycles. Samples were prepared in a glove box at the manufacturing site and transported to the XPS analysis laboratory using an air sensitive sample transport accessory.
- [XPS Study of a Copper-Based Biocidal Film](https://www.kratos.com/application-note/xps-study-of-copper-based-biocidal-film/): X-ray photoelectron spectroscopy (XPS) is ideally suited to the study of copper-based biocidal films. This application note provides an insight into the use of XPS in understanding the surface chemistry, elemental composition, and mechanisms of copper-based biocidal films. By employing XPS, it is possible to gain valuable insights into the oxidation states of copper, the presence of contaminants, and the chemical bonding at the film surface. This knowledge contributes to the optimization of film design and performance, ultimately leading to enhanced antimicrobial properties and improved hygiene

## Helpful Articles
- [Why argon cluster ion sources have become essential for XPS depth profiling](https://www.kratos.com/helpful-article/why-argon-cluster-ion-sources-have-become-essential-for-xps-depth-profiling/): Here we outline the importance of Ar-cluster ions for XPS sputter depth profiling and sample cleaning.
- [Webinar: Understanding the strengths of combining SEM-EDS and XPS for materials characterisation](https://www.kratos.com/helpful-article/webinar-combining-sem-and-xps/): In this webinar experts discuss how scanning electron microscopy (SEM) / energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) address different but complementary length scales & information types.
- [Performance vs Specification: What’s the difference?](https://www.kratos.com/helpful-article/performance-vs-specification/): Here we will attempt to outline the importance of surfaces and X-ray photoelectron spectroscopy (XPS) for materials science.
- [Getting started with XPS analysis](https://www.kratos.com/helpful-article/getting-started-with-xps-analysis/): Here we will attempt to outline the importance of surfaces and X-ray photoelectron spectroscopy (XPS) for materials science.
- [Biology & surface analysis](https://www.kratos.com/helpful-article/biology-surface-analysis/): It could be argued that Aristotle’s postulate that “nature abhors a vacuum” neatly describes why X-ray photoelectron spectroscopy (XPS) has not found routine application to surface characterisation of biological samples.
- [Importance of energy resolution in XPS](https://www.kratos.com/helpful-article/importance-of-energy-resolution-xps/): XPS is a spectroscopic technique and therefore the energy resolution of the instrument is of fundamental importance. 
- [XPS with unrivalled automation](https://www.kratos.com/helpful-article/xps-with-unrivalled-automation/): The AXIS Supra+ has complete automation of sample handling which sets it apart from many photoelectron spectrometers.
- [Workshop recordings : XPS for surface analysis](https://www.kratos.com/helpful-article/workshop-series-xps-for-surface-analysis/): Kratos Analytical is now in its 55th year of manufacturing photoelectron spectrometers which started in 1969 with the ES-100 through to the current state-of-the-art AXIS Supra+ with delay-line detector. As we stride into our second half century of scientific apparatus production, we highlight our progress in the manufacture of photoelectron and mass spectrometers at Kratos Analytical.
- [50 years of XPS](https://www.kratos.com/helpful-article/50-years-of-xps/): Kratos Analytical is now in its 55th year of manufacturing photoelectron spectrometers which started in 1969 with the ES-100 through to the current state-of-the-art AXIS Supra+ with delay-line detector. As we stride into our second half century of scientific apparatus production, we highlight our progress in the manufacture of photoelectron and mass spectrometers at Kratos Analytical.
- [Making complicated simple](https://www.kratos.com/helpful-article/making-complicated-simple/): An article discussing how Kratos is making XPS data acquisition and processing easier for the non-expert.
- [Why is surface analysis important?](https://www.kratos.com/helpful-article/why-is-surface-analysis-important/): Here we will attempt to outline the importance of surfaces and X-ray photoelectron spectroscopy (XPS) for materials science.