X-ray Photoelectron Spectroscopy (XPS) is one of the most powerful surface analysis techniques available today. While XPS testing labs provide highly detailed reports, interpreting those results correctly is essential to extract meaningful insights for research, quality control, or product development.

This guide walks you through the key sections of an XPS testing report and explains how to understand the data your lab partner delivers.

1. Start With the Sample & Test Conditions

Before diving into spectra and numbers, always review the sample description and test parameters. This section confirms:

• Sample material, form, and preparation method
  
  

• Analysis area size and depth (typically 1–10 nm)
  
  

• X-ray source used (e.g., Al Kα)
  
  

• Vacuum level and charge neutralization method

Why it matters: Incorrect sample labeling or preparation can directly affect surface chemistry results. Verifying these details ensures the data truly represents your material.

2. Understanding the Survey Spectrum

The survey (wide scan) spectrum provides a quick overview of all elements present on the surface.

Key points to look for:

• Elemental peaks (C, O, N, Si, metals, etc.)
  
  

• Absence of unexpected contaminants
  
  

• Relative peak intensities
  
  

What it tells you:

• Which elements are present on the surface
  
  

• Whether contamination, oxidation, or residue exists
  
  

• If the surface composition matches expectations

Survey scans are qualitative but essential for planning deeper analysis.

3. Reading High-Resolution (Narrow Scan) Spectra

High-resolution spectra focus on individual elements and are critical for chemical state analysis.

In this section, you’ll see:

• Peak positions (binding energy in eV)
  
  

• Peak shapes and splitting
  
  

• Deconvoluted peaks representing different chemical states

How to interpret:

• Binding energy shifts indicate oxidation states or bonding changes
  
  

• Multiple peaks suggest more than one chemical environment
  
  

• Peak fitting reveals compounds (e.g., metal vs metal oxide)

This is where XPS delivers its real value.

4. Elemental Composition Tables

Most XPS reports include tables listing atomic percentages (at.%).

Things to check:

• Sum of elements close to 100%
  
  

• Comparison between expected vs detected elements
  
  

• Surface enrichment or depletion trends
  
  

Important note: XPS measures surface composition only—not bulk material. Differences from bulk analysis methods (like XRF or ICP) are normal.

5. Carbon 1s Peak: More Than Just Contamination

The C 1s spectrum is commonly used as a reference but also provides valuable insights.

Typical components include:

• C–C / C–H (adventitious carbon)
  
  

• C–O, C=O, O–C=O (functional groups)

Why it’s important:

• Indicates surface functionalization
  
  

• Helps assess cleaning effectiveness
  
  

• Used for charge correction in insulating samples

Never ignore the carbon peak—it often explains surface behavior.

6. Depth Sensitivity & Angle Information

Some reports include angle-resolved XPS (ARXPS) or sputter depth profiling.

What this shows:

• Element distribution with depth
  
  

• Thickness of coatings or oxide layers
  
  

• Interface composition

This data is especially valuable for thin films, coatings, and multilayer materials.

7. Comparing Results With Standards & References

Reputable XPS testing labs compare results with:

• Standard reference databases
  
  

• Published literature values
  
  

• Known calibration materials

You should:

• Check if peak assignments are justified
  
  

• Confirm consistency with known chemistry
  
  

• Ask for references if interpretations affect critical decisions

8. Common Misinterpretations to Avoid

• Assuming bulk composition from XPS results
  
  

• Ignoring surface contamination effects
  
  

• Over-interpreting small atomic percentage differences
  
  

• Comparing XPS data directly with non-surface techniques

Understanding XPS limitations is as important as understanding its strengths.

9. Questions to Ask Your XPS Lab Partner

To get the most value from your report, ask:

• Are peak fits and assignments validated?
  
  

• Was charge correction applied correctly?
  
  

• Can results be correlated with other techniques?
  
  

• What uncertainty or error margins apply?

A good lab partner will gladly clarify and support interpretation.

Conclusion

Interpreting XPS testing reports doesn’t require being an expert spectroscopist—but it does require understanding the structure, terminology, and limitations of the data. By carefully reviewing survey scans, high-resolution spectra, elemental tables, and lab interpretations, you can confidently translate XPS results into actionable insights.

Working closely with an experienced XPS testing lab ensures your surface chemistry data leads to better decisions, improved materials, and stronger product performance.