X-Ray Spectroscopy Analysis: Techniques and Applications Across Science and Industry

X-ray spectroscopic and diffractometric techniques have continued to advance rapidly across the period from 2022–2026, expanding both in instrumental capability and in the breadth of application domains they serve. This review surveys and synthesizes original research, feature articles, instrumentation reports, and expert interviews published by Spectroscopy Online during this period, covering X-ray fluorescence (XRF) in its energy-dispersive, wavelength-dispersive, microbeam, total-reflection, and handheld formats; X-ray diffraction (XRD), including single-crystal, powder, and grazing-incidence variants; X-ray photoelectron spectroscopy (XPS); and energy-dispersive inelastic X-ray scattering (EDIXS). Application areas discussed include food safety and agricultural science, environmental monitoring, cultural heritage and archaeology, forensic and explosive analysis, planetary and extraterrestrial science, energy storage and battery research, materials science and surface analysis, geoscience, and philatelic authentication. Instrumentation trends examined include the commercialization of laboratory micro-XRF, the maturation of AI-assisted portable XRF, and the integration of doubly curved crystal optics in benchtop analyzers for food regulatory compliance. Taken together, the body of work surveyed here illustrates a field in which X-ray methods are moving from specialist laboratory tools to indispensable, field-deployable analytical platforms across disciplines.

Few analytical tool families have proven as durable or as adaptable as those built on the interaction of X-ray radiation with matter. Since the original development of X-ray fluorescence spectrometry in the early twentieth century and the systematization of X-ray diffraction by von Laue and the Braggs, X-ray techniques have been indispensable across materials science, geology, chemistry, environmental analysis, medicine, and industry. In the first quarter of the twenty-first century, that trajectory of versatility has continued, driven above all by advances in detector technology, X-ray optics, portable instrument engineering, and the integration of chemometrics and artificial intelligence into data interpretation workflows.

This review presents a synthesis of the major X-ray spectroscopy and diffractometry articles published by Spectroscopy Online between 2022 and 2026. The coverage spans peer-reviewed feature articles appearing in the print journal Spectroscopy, as well as expert interviews, research summaries, and instrumentation surveys published on the Spectroscopy Online digital platform. Articles are organized by application domain, allowing the reader to trace how a common set of X-ray techniques is being deployed across strikingly different scientific and industrial applications.

The techniques covered include XRF in energy-dispersive (ED-XRF), wavelength-dispersive (WD-XRF), microbeam (μXRF), total-reflection (TXRF), and handheld portable formats; X-ray diffraction (XRD), including powder, single-crystal, and grazing-incidence (GI-XRD) variants; X-ray photoelectron spectroscopy (XPS); and energy-dispersive inelastic X-ray scattering (EDIXS).

X-Ray Spectroscopic and Diffractometric Techniques: A Brief Overview

Before reviewing individual application areas, it is useful to briefly characterize each major X-ray technique as it is employed in the literature surveyed here, noting the instrumental and methodological advances that define the 2022–2026 period.

X-Ray Fluorescence (XRF)

XRF is the most widely deployed X-ray analytical technique in industry and environmental science. It operates by exciting inner-shell electrons of sample atoms with a primary X-ray beam; the characteristic secondary fluorescent X-rays emitted as outer-shell electrons fill the vacancies and are measured by either an energy-dispersive (ED) or wavelength-dispersive (WD) spectrometer to yield a quantitative elemental profile. The technique is nondestructive, rapid, multielemental, and applicable to solids, powders, and liquids with minimal sample preparation, qualities that have made it the method of choice for elemental screening from mining and metals to food safety and art conservation.

The most transformative development in XRF over the past decade, well reflected in the 2022–2026 literature, is the proliferation of handheld and portable ED-XRF instruments. Interview coverage of Thermo Fisher Scientific’s Niton product line^1,2 documents the feedback-driven engineering priorities shaping this market: improved performance through more powerful miniaturized X-ray tubes and faster silicon drift detectors; ergonomic redesign for all-day operator comfort; and tiered product architectures that align cost with genuine field requirements. In parallel, benchtop laboratory XRF has seen comparable advances. A three-part series by Patrick J. Parsons of the New York State Department of Health’s Wadsworth Center^3–5 evaluated second-generation XRF analyzers equipped with doubly curved crystal (DCC) optics, measuring certified reference materials (CRMs) and Food Emergency Response Network (FERN) 2022 proficiency test samples, demonstrating strong analytical agreement and establishing a pathway for XRF as a frontline regulatory food safety screening platform. The underlying study is that of Johnson-Restrepo et al.⁶

Within XRF, two specialist techniques deserve separate mention. Total reflection XRF (TXRF), which can achieve femtogram-level detection limits by exciting samples at sub-critical grazing angles, featured in the 2026 annual “Recent Developments in X-Ray Analysis” article, where it is applied to trace-metal profiling in biological matrices and to multielement analysis of geological apatite.⁷ Also, microbeam XRF (μXRF), which focuses the primary beam to spot sizes of ~3–30 μm using polycapillary or doubly curved crystal optics, received dedicated treatment in a 2025 Spectroscopy feature article by Wright et al.,⁸ cataloguing emerging applications in food and agricultural science for which synchrotron-level resolution can now be achieved on a benchtop instrument.

X-Ray Diffraction (XRD)

XRD exploits the coherent scattering of X-rays by the periodic atomic lattice of crystalline materials to yield structural information: crystal phase identification, lattice parameter determination, crystallite size, and residual strain. In powder XRD the samples measured are polycrystalline and yield a characteristic diffractogram; in single-crystal XRD a larger individual crystal is interrogated for detailed structure analysis and interpretation; and in GI-XRD the beam is directed at very shallow angles on the sample to restrict energy penetration depth, enabling depth-resolved profiling of thin films and nanostructured surfaces.

The 2026 “Recent Developments” feature⁷ documents a GI-XRD investigation in which angle-dependent diffraction at the (111) reflection was used to map bending and torsion profiles along the z-axis of highly dense silicon nanowire arrays, enabling quantification of threading dislocation densities, a compelling example of XRD moving beyond simple phase identification into quantitative nanomechanical sample characterization. Synchrotron XRD has also been applied to cellulose crystallinity indexing in ancient Egyptian wooden artifacts,⁹ and single-crystal XRD has been deployed forensically to characterize crystal phase transitions in ammonium nitrate residues from explosives investigations.¹⁰

X-Ray Photoelectron Spectroscopy (XPS)

XPS uses a monochromatic X-ray beam to eject core-level electrons from the topmost 5–10 nm of a material surface; measurement of photoelectron kinetic energies provides elemental identification and, critically, chemical state information—oxidation states, bonding environments, and coordination chemistry—with a surface sensitivity unavailable to bulk XRF. XPS has become an essential characterization tool in materials science, semiconductor research, and battery electrode analysis. A November 2024 Spectroscopy Online article¹¹ reported on work by Wang, Mueller, and Crumlin that challenged established conventions in XPS characterization of metal oxide surfaces,¹² proposing three alternative frameworks for reliable oxygen vacancy quantification. The broader importance of XPS to lithium-ion battery research is documented in two battery-analysis review articles.^13,14

Energy-Dispersive Inelastic X-Ray Scattering (EDIXS)

EDIXS probes inelastic scattering events to yield information about a sample’s atomic environment and electronic structure, providing a complementary analysis technique to conventional XRF. A notable 2025 application to philatelic authentication¹⁵ demonstrated that EDIXS can discriminate between cancellation ink types on historical postage stamps, a task that XRF with principal component analysis (PCA) accomplishes imperfectly, because XRF captures combined ink-and-paper elemental signals that vary with paper substrate age and composition.

Food Safety and Agricultural Analysis

The use of XRF in food safety has accelerated markedly in the 2022–2026 period, driven by tightening regulatory requirements, the maturation of benchtop instrument performance, and the parallel development of chemometric calibration strategies that permit reliable quantification of elemental analysis in complex organic matrices.

Benchtop XRF with Doubly Curved Crystal Optics for Regulatory Food Safety Monitoring

A three-part series of Spectroscopy Online interview articles: Advances in XRF Instrumentation,³ The Application of XRF Instrumentation in Food Safety Monitoring,⁴ and The Future Outlook of Deploying XRF Analyzers in Testing Complex Food Matrices,⁵ presents an extended conversation with Patrick J. Parsons of the New York State Department of Health’s Wadsworth Center, published in January 2026. Parsons describes a systematic evaluation of two second-generation XRF analyzers equipped with DCC optics, a crystal geometry that collects X-rays over a substantially larger solid angle than flat-crystal designs, delivering significantly improved sensitivity for low-atomic-number elements in organic food matrices. The underlying study⁶ was published in the journal Radiation Physics and Chemistry. Against a range of international CRMs from NIST, the European ERM programme, the National Research Council of Canada, and Japan’s NMIJ, and on FERN 2022 proficiency test samples, the instruments were evaluated and showed strong agreement with certified values across toxic elements, including lead, cadmium, arsenic, and mercury. Parsons identifies matrix complexity, moisture content effects, and the need for matrix-matched calibration as the principal remaining challenges for routine regulatory deployment of XRF analyzers.

Arsenic in Rice and Rice-Based Foods

Researchers at the University of Massachusetts Amherst reported¹⁶ that XRF spectroscopy combined with chemometric modeling provides a rapid, minimally destructive, and analytically accurate alternative to hydride-generation atomic absorption spectrometry and ICP–MS for routine arsenic quantification in rice and rice-based foods. The approach requires minimal sample preparation and is suitable for high-throughput regulatory screening of one of the most widely consumed staple foods globally.

Micro-XRF for Spatially Resolved Elemental Mapping in Food and Agricultural Products

The emergence of laboratory-scale μXRF instruments, which achieve analysis spot sizes of 3–30 μm, was reviewed in depth by Wright, Zierden, Kolomyjec, and Southwell in a January 2025 feature article in Spectroscopy.⁸ The authors document applications across several distinct categories. In crop diagnostics and elemental homeostasis research, μXRF maps the distribution of essential elements within intact, hydrated plant tissue, work previously achievable only at national synchrotron facilities. In food quality and safety screening, μXRF identifies spatial heterogeneity in elemental distribution within processed food products, detects intentional adulteration, and screens packaging materials for toxic-element migration. In biofortification studies, μXRF tracks the incorporation of nutritionally essential elements, notably selenium and zinc, into the endosperm of staple grains such as rice and cowpea. The nondestructive nature of μXRF analysis allows the same samples to be passed to complementary techniques, including ICP–MS, SEM–EDS, and plant physiological sensors for multimodal characterization.

Application Areas: Environmental Monitoring

The role of XRF in environmental analysis was the subject of a comprehensive Spectroscopy review published in March 2026,¹⁷ identifying the ten most influential publications in environmental atomic spectroscopy during 2024–2026. XRF’s central contributions are highlighted alongside ICP–MS/MS and ICP–OES. Key themes include: advances in matrix-effect correction algorithms that have substantially improved XRF accuracy for heterogeneous environmental matrices such as soils, sediments, and atmospheric particulates; comparative evaluations of portable XRF versus laboratory ICP–MS for large-area soil contamination surveys; and the integration of XRF data with ICP–OES in multitechnique environmental monitoring protocols that balance field deployability against laboratory precision. The review reinforces the established but still developing role of portable XRF as a triage and decision-support tool for site characterization, capable of guiding sampling strategies and prioritizing laboratory follow-up, while acknowledging that matrix effects, moisture, and particle size remain performance-limiting factors in direct quantitative field use.

Cultural Heritage and Archaeological Analysis

Multitechnique X-ray analysis has become one of the defining methodological frameworks in heritage science, allowing noninvasive or minimally invasive examination of irreplaceable artifacts. Two March 2026 Spectroscopy Online articles document this convergence in the specific context of ancient Egyptian material culture.

Multitechnique Analysis of a 26th Dynasty Egyptian Wooden Sculpture

A study led by Dina M. Atwa of Beni-Suef University, reviewed in Spectroscopy,⁹ applied a minimally invasive multitechnique framework to a 26th Dynasty (Saite Period, c. 664–525 BCE) Ptah–Sokar–Osiris funerary statuette excavated in 2020 from the Tari cemetery, Giza Pyramids area. Synchrotron XRD established the cellulose crystallinity index and confirmed moderate structural preservation of the wood. FT-IR spectroscopy revealed extensive chemical deterioration, a carbonyl index of 2.22 indicating advanced lignin oxidation and polymer breakdown. XRF mapped the elemental distribution of polychrome pigment layers, identifying materials and characterizing their degradation state. Confocal microscopy characterized surface topography. Together, the four techniques established technical baselines for Saite period workshop practices and provided a conservation framework applicable to related polychrome wooden artifacts in museum and archaeological collections.

Broader Review: Spectroscopy Techniques in Egyptian History

A companion overview¹⁸ places this and related work within a broader survey of how spectroscopic techniques, such as XRF and XRD, are reshaping what is scientifically accessible in the study of ancient Egypt. The article surveys noninvasive analytical frameworks applied to pigments, mummified materials, papyri, and architectural stone, documenting how the combination of rapid elemental screening by portable XRF with more targeted structural and chemical analysis by XRD, Raman, and FT-IR is making comprehensive material characterization feasible even for museum-held objects that cannot leave institutional custody.

Application Areas: Geoscience for Volcanology and Fluid–Rock Interaction

A June 2025 video interview series with geoscientist Pooja Sheevam,¹⁹ the final installment of which covered the interpretation of mineralogical and geochemical processes in Hawaii, documents the application of SEM–EDS and bulk XRF to fluid–rock interaction studies in geothermal drill core. The PTA-2 drill core from the Pohakuloa Training Area on the Big Island of Hawaii provided a geological context distinctly different from the more commonly studied active-margin hydrothermal systems: a hotspot setting remote from large rift zones or tectonic boundaries. XRF and SEM–EDS characterization of mineral alteration phases in the drill core provided the elemental and compositional data needed to interpret fluid pathways, temperature gradients, and mineral precipitation sequences within this intraplate geothermal system. Sheevam explicitly contrasts the Hawaiian setting with Iceland, where a large rift province drives pervasive hydrothermal alteration, noting that the more localized rifting geometry at the Hawaiian hotspot produces a fundamentally different fluid–rock interaction regime that XRF-anchored mineralogical characterization helps to constrain.

Forensic and Explosive Residue Analysis

Single-crystal XRD made an important forensic contribution in a study by Estevanes, Jernigan, Zall, and Monjardez published in the Journal of Raman Spectroscopy¹⁰ and covered in a February 2025 Spectroscopy Online interview article.²⁰ The study investigated ammonium nitrate (AN) lattice vibrations in ammonium nitrate fuel oil (ANFO) residues collected from postblast substrates following the controlled detonation of two improvised explosive devices (IEDs). Confocal Raman microscopy of the recovered crystalline material revealed lattice vibration patterns distinct from those of intact AN, including spectral shifts and new bands in the low-frequency region, indicating thermally driven phase transitions induced by the shock and heat of detonation. Single-crystal XRD confirmed the structural changes independently. Lead author Monjardez characterizes the work as a fundamental study of AN crystal phase transitions rather than a forensic application per se, but the demonstration that thermally altered AN can be reliably distinguished from intact AN using Raman and XRD has direct implications for postblast scene investigation.

Application Areas: Planetary Science and Meteoritics

X-ray diffraction plays a central role in extraterrestrial material characterization, providing the phase identification that complements elemental profiles from XRF and molecular signatures from Raman spectroscopy. A comprehensive April 2026 analysis of the Tiglit meteorite,²¹ summarizing the work of Karczemska et al.,²² illustrates this multitechnique synergy at its most productive application. Tiglit is an aubrite-class stony meteorite recovered from the Sahara Desert in 2021 shortly after its observed fall. The integrated methodology, using SEM–EDS, powder XRD, and Raman spectroscopy, was explicitly designed to maximize phase and chemical information while minimizing destructive sampling of irreplaceable material. XRD confirmed the canonical aubrite mineral assemblage: enstatite pyroxene, olivine, plagioclase feldspar, metal sulfides, and iron oxides. SEM–EDS mapped elemental distributions at the grain scale. Together, the techniques yielded an unexpected finding: several mineral phases not typical of aubrites, namely, calcite, polymorphic SiO₂ forms (quartz and cristobalite), and carbon phases, imply a more complex formation and alteration history than previously attributed to this meteorite class and broaden the recognized compositional makeup of aubrite-class extraterrestrial materials.

Materials Science and Surface Chemistry

XPS for Oxygen Vacancy Quantification in Metal Oxides

Metal oxides are industrially critical materials used extensively in catalysis, energy conversion, electronic devices, and structural ceramics, and their properties are profoundly influenced by oxygen vacancy concentrations. XPS has long been the preferred surface analytical tool for oxygen vacancy characterization, but this feature, observed at 531–532 eV in O 1s spectra, has been widely and often incorrectly assigned as a direct indicator of oxygen vacancies. A 2024 study by Wang, Mueller, and Crumlin,¹² covered on Spectroscopy Online,¹¹ addressed this directly by proposing three methodologically sounder alternatives: (i) monitoring XPS-measured changes in cation valence state as a proxy for vacancy formation; (ii) evaluating normalized surface oxygen-to-cation stoichiometry from spectral intensities; and (iii) tracking binding-energy shifts arising from electron doping associated with vacancy formation. The authors provide guidance on which approach is best suited to specific material systems, advancing the methodological rigor of oxygen vacancy analysis with direct consequences for the design and characterization of next-generation energy storage and catalytic materials.

XPS and XRF in Lithium-Ion Battery Research

X-ray methods, such as XPS and XRF, are central to the analytical tool kit reviewed in two major Spectroscopy Online battery-research articles.^13,14 XRF provides the elemental composition profiling needed to characterize cathode active materials, for example, nickel-manganese-cobalt oxide, nickel-cobalt-aluminum oxide, and lithium iron phosphate. XRF is also able to verify compositional uniformity and the removal of trace impurities, analysis work whose accuracy directly determines battery performance and lifespan. XPS provides the complementary surface-sensitive view, for example, solid-electrolyte interphase composition and thickness evolution, oxidation state mapping at electrode surfaces, coating homogeneity assessment, and identification of degradation products. Interview coverage of the Weker Group at SLAC National Accelerator Laboratory²³ documents how synchrotron X-ray techniques are being applied to in-operando battery cell geometry studies, and in tracking electrode structural evolution during charge/discharge cycling in realistic small-format pouch cell configurations.

Philatelic Authentication and Ink Analysis

An August 2025 Spectroscopy Online article¹⁵ reports on a study by researchers at the Universidad Nacional de Córdoba, Argentina, that introduced EDIXS as a superior tool to XRF for the authentication of postal stamps and discrimination of cancellation inks. The philatelic authentication problem is a useful case study of the limitations of XRF in complex multilayer systems. Conventional XRF with PCA produces elemental profiles that reflect the combined chemistry of the cancellation ink and the paper substrate. Because paper composition has changed substantially over the nearly century-long span of the stamps studied, those substrate variations obscure the ink-specific information that authenticators need. EDIXS, by probing atomic coordination environments and oxidation states rather than merely elemental composition, provides an ink-specific signal largely independent of the chemistry of the paper substrate. Applied to nine Argentine stamps spanning approximately 100 years, the technique achieved discrimination between cancellation ink types that XRF alone could not reliably determine. The methodological principle, that EDIXS resolves ink chemistry independent of substrate, has an exciting and broader implication for authentication work on historical documents, manuscripts, and artworks.

Instrumentation Advances Revealing New XRF Systems (2025–2026)

Beyond the application-driven literature, a significant segment of Spectroscopy Online’s 2022–2026 X-ray coverage consists of instrumentation surveys and new-product reviews that document the advancing technical baseline against which future applications will be developed. The 2026 New Product Advances survey²⁴ highlights two XRF instruments of particular note.

The Shimadzu ALTRACE is positioned as a next-generation nondestructive elemental analyzer, featuring a high-energy 65 kV X-ray tube paired with a high-count-rate detector, a 48-sample autosampler for high-throughput operation, and multifilter optimization that delivers parts per million (ppm)-to-percent dynamic range in a single analytical run across solids, powders, and liquids.

The XOS portable EDXRF system integrates real-time AI-assisted spectral interpretation with sulfur analysis per ASTM D4294 and measurement of up to twelve elements from phosphorus through zinc at sub-ppm levels. The incorporation of on-device AI for spectral interpretation reflects the broader trend toward intelligent, autonomous analytical instruments capable of expert-level data reduction in the field, a trend that recurs across the 2025–2026 instrument development cycle.

Annual instrumentation reviews by Miseo and Bradley for 2022²⁵ and 2023²⁶ confirm a consistent instrument development trajectory: the introduction of new XRF instruments by established manufacturers, incremental improvements in source power and detector speed, and the progressive expansion of portable XRF capabilities toward laboratory-grade quantitative analysis.

Conclusions

The body of X-ray spectroscopy and diffractometry work published by Spectroscopy Online between 2022 and 2026 paints a coherent picture of a technique family whose breadth of application continues to expand even as its core technologies mature. Several overarching trends are apparent.

Multitechnique integration has become the norm rather than the exception. Virtually every application-domain article surveyed here deploys two or more X-ray techniques or combines X-ray methods with Raman, FT-IR, ICP–MS, or electron microscopy. Multitechnique integration is required because the analytical questions being asked demand more information than any single technique can provide. The Egyptian wooden sculpture study⁹ exemplifies this: XRF, XRD, FT-IR, and confocal microscopy each contributed distinct, nonredundant information.

Portable and field-deployable XRF has crossed an important performance threshold. The Parsons series^3–5 documents instruments that now deliver, under appropriate conditions and with suitable calibration, quantitative results meeting regulatory and proficiency-test standards, a qualitative shift from the screening-only role that portable XRF occupied a decade ago.

Spatial information, such as elemental mapping, is an increasingly important analysis requirement. The commercialization of laboratory μXRF⁸ and the deployment of synchrotron X-ray techniques in battery research²³ both reflect demand not only for elemental composition but also for its spatial distribution at the micrometer-to-submillimeter scale.

Artificial intelligence integration is an emerging instrumentation trend. The XOS EDXRF system’s on-device AI-assisted spectral interpretation²⁴ is an early commercial expression of a broader trend. As spectral libraries and machine-learning calibration models become more robust and more tightly coupled to instrument firmware, the barrier between raw spectral data and actionable analytical results will continue to be lowered, particularly for portable instruments deployed in the field.

The work surveyed here collectively demonstrates that X-ray spectroscopy, far from being a mature, static discipline, remains a dynamic, evolving analytical ecosystem whose methods are being continuously refined, creatively recombined, and applied to problems well beyond the metals and materials characterization that originally drove their development. This is an exciting time in the history of X-ray analysis for both instrumentation advances and new applications.

References

1. Margeson, J.; Wetzel, W. Addressing Industry Challenges in Handheld XRF Instrumentation. Spectroscopy Online, 2026. https://www.spectroscopyonline.com/view/addressing-industry-challenges-in-handheld-xrf-instrumentation (accessed June 23, 2026).

2. Margeson, J.; Wetzel, W. Light-Metal Sorting and Rugged Engineering in Handheld XRF Instrumentation. Spectroscopy Online, 2026. https://www.spectroscopyonline.com/view/light-metal-sorting-and-rugged-engineering-in-handheld-xrf-instrumentation (accessed June 23, 2026).

3. Parsons, P. J.; Wetzel, W. Advances in XRF Instrumentation. Spectroscopy Online, 2026. https://www.spectroscopyonline.com/view/advances-in-xrf-instrumentation (accessed June 23, 2026).

4. Parsons, P. J.; Wetzel, W. The Application of XRF Instrumentation in Food Safety Monitoring. Spectroscopy Online, 2026. https://www.spectroscopyonline.com/view/the-application-of-xrf-instrumentation-in-food-safety-monitoring (accessed June 23, 2026).

5. Parsons, P. J.; Wetzel, W. The Future Outlook of Deploying XRF Analyzers in Testing Complex Food Matrices. Spectroscopy Online, 2026. https://www.spectroscopyonline.com/view/the-future-outlook-of-deploying-xrf-analyzers-in-testing-complex-food-matrices (accessed June 23, 2026).

6. Johnson-Restrepo, B.; Blain, E.; Judd, C.; Tysoe, A.; Parsons, P. J. New Developments in Monochromatic Energy Dispersive X-ray Fluorescence Instrumentation for Monitoring Toxic Elements in Food Matrices: Advantages and Limitations. Radiat. Phys. Chem. 2025, 234, 112749. https://doi.org/10.1016/j.radphyschem.2025.112749

7. Spectroscopy Editors. Recent Developments in X-Ray Analysis; Spectroscopy Online, 2026. https://www.spectroscopyonline.com/view/recent-developments-in-x-ray-analysis (accessed June 23, 2026).

8. Wright, D. D.; Zierden, M. R.; Kolomyjec, S.; Southwell, B. Applications of Micro X-Ray Fluorescence Spectroscopy in Food and Agricultural Products. Spectroscopy 2025, 40 (1), 8–15. https://www.spectroscopyonline.com/view/applications-of-micro-x-ray-fluorescence-spectroscopy-in-food-and-agricultural-products (accessed June 23, 2026).

9. Wetzel, W.; Spectroscopy Staff. Using XRF, XRD, FT-IR, and Confocal Microscopy to Characterize Late Period Egyptian Wooden Sculptures; Spectroscopy Online, 2026. https://www.spectroscopyonline.com/view/using-xrf-xrd-ft-ir-and-confocal-microscopy-to-characterize-late-period-egyptian-wooden-sculptures (accessed June 23, 2026).

10. Estevanes, J.; Jernigan, N.; Zall, C.; Monjardez, G. The Characterization of the Lattice Vibrations of Ammonium Nitrate in ANFO Mixture after Authentic Detonations Using Confocal Raman Microscopy and Single Crystal X-ray Diffraction. J. Raman Spectrosc. 2025, 56 (2), 146-154. https://doi.org/10.1002/jrs.6752

11. Wetzel, W. Analyzing Oxygen Vacancy Using X-ray Photoelectron Spectroscopy. Spectroscopy Online, 2024. https://www.spectroscopyonline.com/view/analyzing-oxygen-vacancy-using-x-ray-photoelectron-spectroscopy (accessed June 23, 2026).

12. Wang, J.; Mueller, D. N.; Crumlin, E. J. Recommended Strategies for Quantifying Oxygen Vacancies with X-ray Photoelectron Spectroscopy. J. Eur. Ceram. Soc. 2024, 44 (15), 116709. https://doi.org/10.1016/j.jeurceramsoc.2024.116709

13. Workman, J., Jr. A Comprehensive Review of Spectroscopic Techniques for Lithium-Ion Battery Analysis. Spectroscopy Online, 2026. https://www.spectroscopyonline.com/view/a-comprehensive-review-of-spectroscopic-techniques-for-lithium-ion-battery-analysis (accessed June 23, 2026).

14. Workman, J., Jr.; Wetzel, W. Lithium-Ion Battery Analysis: Four Years of Spectroscopic Advances in Research, Manufacturing, and Quality Assessment. Spectroscopy Online, 2026. https://www.spectroscopyonline.com/view/lithium-ion-battery-analysis-four-years-of-spectroscopic-advances-in-research-manufacturing-and-quality-assessment (accessed June 23, 2026).

15. Wetzel, W. An Inside Look at X-ray Techniques in Stamp Collecting; Spectroscopy Online, 2025. https://www.spectroscopyonline.com/view/an-inside-look-at-x-ray-techniques-in-stamp-collecting (accessed June 23, 2026).

16. Wetzel, W.; Spectroscopy Staff. Routine Arsenic Quantification in Rice and Rice-Based Foods. Spectroscopy Online, 2026. https://www.spectroscopyonline.com/view/routine-arsenic-quantification-in-rice-and-rice-based-foods (accessed June 23, 2026).

17. Workman, J., Jr. The Top 10 Most Influential Applications of Atomic Spectroscopy in Environmental Analysis (2024–2026). Spectroscopy Online, 2026. https://www.spectroscopyonline.com/view/the-top-10-most-influential-applications-of-atomic-spectroscopy-in-environmental-analysis-2024-2026- (accessed June 23, 2026).

18. Wetzel, W.; Spectroscopy Staff. How Spectroscopy Is Uncovering Ancient Egyptian History; Spectroscopy Online, 2026. https://www.spectroscopyonline.com/view/how-spectroscopy-is-uncovering-ancient-egyptian-history (accessed June 23, 2026).

19. Wetzel, W. The Interpretation of Mineralogical and Geochemical Processes: An Interview with Pooja Sheevam, Part V. Spectroscopy Online, 2025. https://www.spectroscopyonline.com/view/the-interpretation-of-mineralogical-and-geochemical-processes-an-interview-with-pooja-sheevam-part-v (accessed June 23, 2026).

20. Wetzel, W. Investigating ANFO Lattice Vibrations after Detonation with Raman and XRD. Spectroscopy Online, 2025. https://www.spectroscopyonline.com/view/investigating-anfo-lattice-vibrations-after-detonation-with-raman-and-xrd (accessed June 23, 2026).

21. Wetzel, W.; Spectroscopy Staff. Studying Tiglit Meteorite Using Raman Spectroscopy and X-ray Diffraction. Spectroscopy Online, 2026. https://www.spectroscopyonline.com/view/studying-tiglit-meteorite-using-raman-spectroscopy-and-x-ray-diffraction (accessed June 23, 2026).

22. Karczemska, A.; Dudek, M.; Januszewicz, B.; Jakubowski, T.; Mitura, S. Raman Spectroscopy and X-ray Diffraction Investigations of Phase Composition of Tiglit Meteorite. Materials 2026, 19 (3), 624. https://doi.org/10.3390/ma19030624

23. Wetzel, W. Inside the Laboratory: The Weker Group at SLAC National Accelerator Laboratory, Part III. Spectroscopy Online, 2025. https://www.spectroscopyonline.com/view/inside-the-laboratory-the-weker-group-at-slac-national-accelerator-laboratory-part-iii (accessed June 23, 2026).

24. Workman, J., Jr. New Product Advances in Vibrational and Atomic Spectroscopy (2025–2026). Spectroscopy Online, 2026. https://www.spectroscopyonline.com/view/new-product-advances-in-vibrational-and-atomic-spectroscopy-2025-2026- (accessed June 23, 2026).

25. Miseo, E.; Bradley, M. S. 2022 Review of Spectroscopic Instrumentation. Spectroscopy Online, 2022. https://www.spectroscopyonline.com/view/2022-review-of-spectroscopic-instrumentation (accessed June 23, 2026).

26. Miseo, E. 2023 Review of Spectroscopic Instrumentation. Spectroscopy Online, 2023. https://www.spectroscopyonline.com/view/2023-review-of-spectroscopic-instrumentation (accessed June 23, 2026).