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Because of the importance of surfaces and interfaces in many scientific and technological areas, the use of x-ray photoelectron spectroscopy (XPS) has been growing exponentially. Although XPS is being used to obtain useful information about the surface composition of samples, much more information about materials and their properties can be extracted from XPS data than commonly obtained. This paper describes some of the areas where alternative analysis methods or experimental design can obtain information about the near-surface region of a sample, often information not available in other ways. Experienced XPS analysts are familiar with many of these methods, but they may not be known to new or casual XPS users, and sometimes, they have not been used because of an inappropriately assumed complexity. The information available includes optical, electronic, and electrical properties; nanostructure; expanded chemical information; and enhanced analysis of biological materials and solid/liquid interfaces. Many of these analyses can be conducted on standard laboratory XPS systems, with either no or relatively minor system alterations. Topics discussed include (1) considerations beyond the “traditional” uniform surface layer composition calculation, (2) using the Auger parameter to determine a sample property, (3) use of the D parameter to identify sp2 and sp3 carbon information, (4) information from the XPS valence band, (5) using cryocooling to expand range of samples that can be analyzed and minimize damage, and (6) using electrical potential effects on XPS signals to extract chemically resolved electrical measurements including band alignment and electrical property information.

As critical transition zones between the land and the sea, estuaries are not only hotspots of hydrogeochemical and microbial processes/reactions, but also play a vital role in processing and transferring terrestrial fluxes of metals and nutrients to the sea. This study focused on three estuaries in the Gulf of Bothnia. All of them experience frequent inputs of acidic and Mn/metal-rich creek waters due to flushing of acid sulfate soils that are widespread in the creekś catchments. Analyzing existing long-termwaterchemistrydata revealed a strong seasonal variation of Mn loads, with the highest values in spring (after snow melt) and autumn (after heavy rains). We sampled surface waters, suspended particulate matter (SPM), and sediments from the estuarine mixing zones and determined the loads and solid-phase speciation of Mn as well as the composition and metabolic potentials of microbial communities. The results showed that the removal, cycling, and lateral transport of Mn were governed by similar phases and processes in the three estuaries. Manganese X-ray absorption spectroscopy data of the SPM suggested that the removal of Mn was regulated by silicates (e.g., biotite), organically complexed Mn(II), and MnOx (dominated by groutite and phyllomanganates). While the fractional amounts of silicate-bound Mn(II) were overall low and constant throughout the estuaries, MnOx was strongly correlated with the Mn loadings of the SPM and thus the main vector for the removal of Mn in the central and outer parts of the estuaries, along with organically complexed Mn(II). Down estuary, both the fractional amounts and average Mn oxidation state of the MnOx phases increased with (i) the total Mn loads on the SPM samples and (ii) the relative abundances of several potential Mn-oxidizing bacteria (Flavobacterium, Caulobacter, Mycobacterium, and Pedobacter) in the surface waters. These features collectively suggested that the oxidation of Mn, probably mediated by the potential Mn-oxidizing microorganisms, became more extensive and complete towards the central and outer parts of the estuaries. At two sites in the central parts of one estuary, abundant phyllomanganates occurred in the surface sediments, but were converted to surface-sorbed Mn(II) phases at deeper layers (>3–4 cm). The occurrence of phyllomanganates may have suppressed the reduction of sulfate in the surface sediments, pushing down the methane sulfate transition zone that is typically shallow in estuarine sediments. At the outermost site in the estuary, deposited MnOx were reduced immediately at the water–sediment interface and converted most likely to Mn carbonate. The mobile Mn species produced by the Mn reduction processes (e.g., aqueous Mn(II) and ligand complexed Mn(III)) could partly diffuse into the overlying waters and, together with the estuarine Mn loads carried by the surface waters, transfer large amounts of reactive Mn into open coastal areas and subsequently contribute to Mn shuttling and inter-linked biogeochemical processes over the seafloor. Given the widespread occurrence of acid sulfate soils and other sulfidic geological materials on many coastal plains worldwide, the identified Mn attenuation and transport mechanisms are relevant for many estuaries globally.

X-ray photoelectron spectroscopy was used to analyze commercially available powders of five monosaccharides: glucose, glucosamine, galactosamine, glucuronic acid, and N-acetyl galactosamine. These powders were pressed onto a sample holder and analyzed as received from the manufacturer. Survey spectra and high-resolution spectra of O 1s and C 1s of all monosaccharides are reported, including N 1s for N-acetyl galactosamine, glucosamine, and galactosamine and Cl 2p for glucosamine and galactosamine. Furthermore, the presented data are compared with theoretical values, and differences are discussed.

Nanoparticles used for medical applications commonly possess coatings or surface functionalities intended to provide specific behavior in vivo, for example, the use of PEG to provide stealth properties. Direct, quantitative measurement of the surface chemistry and composition of such systems in a hydrated environment has thus far not been demonstrated, yet such measurements are of great importance for the development of nanomedicine systems. Here we demonstrate the first use of cryo-XPS for the measurement of two PEG-functionalized nanomedicines: a polymeric drug delivery system and a lipid nanoparticle mRNA carrier. The observed differences between cryo-XPS and standard XPS measurements indicate the potential of cryo-XPS for providing quantitative measurements of such nanoparticle systems in hydrated conditions.

X-ray photoelectron spectroscopy was used to analyze commercially available powders of thymine, uracil, cytosine, guanine, adenine, as well as DNA isolated from salmon testes and RNA from torula yeast. The powders were pressed onto a sample holder and analyzed as received from the manufacturer. Survey spectra and high-resolution spectra of O 1s, N 1s, C 1s of all nucleobases are reported, including a small Na 1s contamination in cytosine. Spectra of DNA and RNA are also included for comparison. Furthermore, the presented data are compared with previously published results, as well as theoretical values, and differences are discussed.

Main obstacle for adopting continuous processes as a standard technology for Mizoroki-Heck reaction usually lies in its specific reaction mechanism. Here we present an important step forward answering the challenges unraveled through a comprehensive study that provides deeper understanding on the Mizoroki-Heck reaction, in particular the case when iodobenzene and butyl acrylate react in a continuous packed bed reactor in the presence of a Pd Supported Ionic Liquid Catalyst (SILCA). On-line UV–VIS spectrometry supported by ICP-OES, TEM and XPS measurements were carried out and the catalyst leaching was minimized. Finally, simple continuous flow process was proposed resulting in a high catalytic activity (up to 1470 mol_ArI mol_Pd⁻¹h⁻¹) and reaching productivity in the range of 12,000 to 16,000 mol_ArI mol_Pd⁻¹ thus competing with the performance of commercial catalysts.

Cryogenic x-ray photoelectron spectroscopy was used to analyze the cell envelope of intact and hydrated Gram-negative bacteria of the species Pseudomonas fluorescens. We used a reference strain, DSM50090, from the German microbial culture collection, which we previously have suggested would function well as a reference strain for future XPS analyses of Gram-negative bacteria. Bacteria were grown on nutrient agar plates at room temperature, collected with a cultivation loop, and washed using phosphate buffered saline. An aliquot of the cell pellet was fast-frozen on the sample holder in the sample introduction chamber to a temperature of 103 K and kept frozen throughout the measurement. Survey spectra and high-resolution spectra of Na 1s, O 1s, N 1s, C 1s, Cl 2p, S 2p, and P 2p are reported. The spectra obtained from the analyzed cells represent a combined signal from O, N, C, and S atoms in proteins, lipids, and polysaccharides at the cell surface. Furthermore, signal from P, Na, K, and Cl atoms was present both originating from processes in the cell envelope and remnants from the wash buffer.

The omnipresence of microplastics (MPs) across Earth's surface has raised concerns about their environmental impact and created an urgent need for methods to identify them in complex soil and sedimentary matrices. However, detecting MPs in the O horizons of soils is difficult because plastic polymers share many physical and chemical properties with natural soil organic matter (SOM). In this study, we assessed whether sodium hypochlorite (NaOCl), a reagent that can oxidize SOM and simultaneously preserve mineral constituents, can be used for MP analysis and characterization in soil environments. In addition, we scrutinized how factors such as MP size, polymer type, extraction methods, and soil matrix affect the recovery of microplastic particles. We used both hydrophobic and density-dependent separation methods to assess the effects of our oxidation treatment on the recovery of MP. We observed that NaOCl effectively removed SOM without greatly altering the surface properties of resistant MP polymers (polypropylene, polylactic acid, low-density polyethylene, and polyethylene terephthalate), which were characterized using scanning electron microscopy and Fourier-transform infrared spectroscopy after SOM removal. The NaOCl treatment caused some chlorination and formation of additional C–OH bonds on polymer surfaces, which likely contributed to the reduced efficiency of the hydrophobic-based (oil) extraction. We conclude that NaOCl treatment can improve detection of MPs in SOM-rich soil and that recovery of MPs from soils is influenced by MP size, polymer type, extraction method, and soil type, which makes it challenging to develop a universal analytical method.

Minerals exposed to moist air stabilize thin water films that drive a score of chemical reactions of great importance to water-unsaturated terrestrial environments. In this study, we identified Mn (oxy)(hydr)oxide nanocoatings formed by the dissolution, oxidation and precipitation of Mn in oxygenated water films grown on rhodochrosite (MnCO₃) microparticles. Nanocoatings that could be identified by vibrational spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and (scanning and transmission) electron microscopy formed in water films containing the equivalent of at least 7 monolayers (∼84 H₂O/nm²). These films were formed by exposing microparticles to moist air with at least 50% relative humidity (RH). Films of neutral pH reacted up to 14% of the Mn^II located in the topmost ∼5 nm region of the microparticles in atmospheres of up to 90% RH for 7 d. These reactions produced MnOOH, birnessite (MnO₂) and hausmannite (Mn₃O₄) nanoparticles of low crystallinity, while exposure to atmospheric air for 1 yr. converted only 2% of Mn^II in this region to MnOOH. In contrast, reactions in alkaline water films converted up to ∼75% of the Mn^II but only after 16 d of reaction. These films produced MnOOH and MnO₂ of low crystallinity, as well as crystalline hausmannite. Kinetic modeling of the time-resolved growth of the Mn[sbnd]O stretching vibrational bands of these nanocoatings revealed two concurrent reaction processes. A 1^rst-order process was assigned to nucleation events terminating only after a few hours, and a 0-order process was assigned to the sustained growth of nanocoatings from these nuclei over longer reaction time. By identifying nanocoatings formed by water film-driven reactions on rhodochrosite, our study adds new insight into mineralogical transformations relevant to anoxic–oxic boundaries in water-unsaturated environments.

Interaction between microorganisms and their surroundings are generally mediated via the cell wall or cell envelope. An understanding of the overall chemical composition of these surface layers may give clues on how these interactions occur and suggest mechanisms to manipulate them. This knowledge is key, for instance, in research aiming to reduce colonization of medical devices and device-related infections from different types of microorganisms. In this context, X-ray photoelectron spectroscopy (XPS) is a powerful technique as its analysis depth below 10 nm enables studies of the outermost surface structures of microorganism. Of specific interest for the study of biological systems is cryogenic XPS (cryo-XPS). This technique allows studies of intact fast-frozen hydrated samples without the need for pre-treatment procedures that may cause the cell structure to collapse or change due to the loss of water. Previously, cryo-XPS has been applied to study bacterial and algal surfaces with respect to their composition of lipids, polysaccharides and peptide (protein and/or peptidoglycan). This contribution focuses onto two other groups of microorganisms with widely different architecture and modes of life, namely fungi and viruses. It evaluates to what extent existing models for data treatment of XPS spectra can be applied to understand the chemical composition of their very different surface layers. XPS data from model organisms as well as reference substances representing specific building blocks of their surface were collected and are presented. These results aims to guide future analysis of the surface chemical composition of biological systems.