What Is a Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR)?
Attenuated Total Reflectance – Fourier Transform Infrared (ATR-FTIR) Spectroscopy is a rapid, non-destructive technique that identifies a material’s chemical composition, structure (functional groups), and optical properties. This form of Fourier Transform Infrared spectroscopy is primarily for surface and bulk chemical compositional analysis across industries where speed, reproducibility, and minimal preparation are essential.
Zero Sample Preparation
Broad Applications
Versatility
Why Use ATR-FTIR?
ATR-FTIR analysis is versatile and requires little or no sample preparation, making it ideal for rapid chemical composition analysis. It can handle solids, liquids, pastes, and water-based solutions that are challenging for other infrared methods. ATR-FTIR spectroscopy also allows real-time monitoring of reactions and surface-level changes without altering the sample.
Non-Destructive Testing
Accurate Surface Chemical Analysis
Real-Time Monitoring
How ATR-FTIR Works
Attenuated Total Reflectance Fourier Transform Infrared spectroscopy relies on a specialized ATR crystal with a high refractive index. In ATR-FTIR analysis, infrared light is bounced through the crystal in contact with the sample. The light forms an evanescent wave that penetrates just a few microns into the surface, interacting with the material.
The absorbed light corresponds to the vibrational modes of a sample’s chemical bonds thus, producing an FTIR spectrum with peaks that correspond to functional groups unique to the sample. ATR-FTIR spectroscopy helps identify compounds, examine optical properties, monitor reactions, and assess material composition in the pharmaceuticals, materials science, forensics, and environmental testing.
- Diamond ATR crystals are durable and suitable for most materials due to their hardness and high refractive index.
- Germanium ATR crystals provide shallower penetration depth and are ideal for thin films or highly absorbing samples such as carbon black.
Because ATR-FTIR only probes surface layers, it is exceptionally well-suited for thin films, coatings, and layered materials.
Equipment Used for ATR-FTIR
Covalent's ATR-FTIR analysis is powered by advanced ThermoFisher instrumentation, delivering high-resolution FTIR spectral analysis with flexible sampling modes.
ThermoFisher Scientific Nicolet iS50 FT-IR Spectrometer
- Spectral range: 7800 to 350 cm⁻¹ with resolution < 0.09 cm⁻¹.
- Resolution: < 0.09 cm⁻¹.
- Wavenumber accuracy: < 0.005 cm⁻¹.
- Multi-detector configuration to support advanced analytical modes.
Integrated Accessories:
- Diamond ATR (standard and high-pressure) for hard samples, Ge ATR for carbon-filled or opaque materials.
- Variable angle ATR and transmission model for precision thin film analysis.
- Reflectance mode for metallic surface coatings and contaminants on reflective surfaces.
- Suppression of unwanted IR radiation from internal and temperature-controlled DLaTGS detectors for improved detector stability.
ThermoFisher Scientific Nicolet Continuum IR Microscope
- 15x and 32x objectives.
- Detector options: Narrow-band MCT-A High performance (4000 to 750 cm⁻¹) and Narrow-band MCT-A (50um element, 4000 to 700 cm⁻¹).
- Sampling modes: Transmission, reflection, Ge ATR, and diamond cell transmission.
- ATR objectives: Dedicated with interchangeable Diamond, Ge, ZnSe, and Si crystals; integrated pressure sensor for robust sampling.
- Grazing angle objective: NA 0.99 for sensitive thin-film and surface analysis.
- Detector configuration: Dual detector bay supporting MCT-A, MCT-B, and InGaAs detectors for broad spectral coverage.
Key Differentiators
Attenuated Total Reflectance FTIR delivers rapid results with minimal sample preparation. It directly analyzes solids, liquids, gels, and powders while maintaining high reproducibility and accuracy in surface chemical analysis. Laboratories use it for both routine checks and advanced ATR-FTIR spectroscopy studies, making it a versatile and reliable technique.
Strengths
- Rapid, non-destructive identification of solids, liquids, gels, and coatings: Ideal for verifying materials and screening unknowns.
- Minimal to no sample preparation: No dilution, slicing, or special handling required.
- Surface-sensitive analysis: Probes a few microns deep to detect coatings, films, and contaminants.
- Highly reproducible spectra: Uses durable diamond or Ge ATR crystals across a wide range of materials.
- Real-time monitoring capability: Enables tracking of reactions or surface changes.
Limitations
- Surface-only sensitivity: Limited penetration depth (0.5-2 µm) means bulk chemistry is not measured.
- Variable quantitative precision: Can be affected by surface irregularities or poor crystal contact.
- Sample constraints: Not suitable for rough or highly absorbing samples without specialized ATR crystals (e.g., Ge).
- Thickness measurement limits: Cannot measure exact layer thickness, only relative trends or composition changes.
- Potential spectral interference: CO₂ or moisture may affect results without proper purging or correction.
Example Outputs
Sample Requirements
- Works with solids, liquids, gels, powders, and coatings.
- The best results are when the sample covers the ATR crystal (>1 mm in diameter).
- Microscope mode enables analysis of small areas down to 20 µm.
- The maximum sample size height for micro ATR-FTIR services is ~20 mm.
ATR-FTIR Applications by Industry
Electronics
- Identifying unknown residues on printed circuit boards (PCBs).
- Detecting contamination on metal pins, plates, or coatings.
- Comparing good vs. bad material lots for quality assurance.
Aerospace
- Surface analysis of coatings and thin films on components.
- Monitoring degradation in polymers or composite materials.
- Confirming raw material identity and batch consistency.
Polymers & Materials Science
- Verifying polymer blend composition.
- Assessing surface-level degradation or chemical changes.
- Screening thin films, coatings, and layered materials.
Pharmaceuticals & Biomedical Devices
- Surface chemical analysis of 3D-printed biomedical polymers.
- Rapid identification of active materials and contaminants.
- Monitoring degradation or chemical consistency in formulations.
Energy & Battery Materials
- Assessing surface degradation in electrodes or separators.
- Identifying contaminant residues on energy storage materials.
- Verifying the composition of thin films and coatings.
Techniques That Complement ATR-FTIR
ATR-FTIR is a strong first-pass screening method, but deeper insights often require additional techniques. At Covalent, ATR-FTIR analysis is frequently paired with methods that extend its reach into molecular, elemental, and trace-level domains.
ATR-FTIR Services often serve as the first step in a multi-technique workflow, guiding which complementary methods will provide the most value for complete material characterization.
The commonly paired techniques include:
Why Choose Covalent for Your ATR-FTIR Needs?
Covalent’s ATR-FTIR lab combines speed, accuracy, and flexibility. We analyze solids, thin films, and microsamples with minimal prep with both benchtop and microscope-based systems.
Our scientists bring chemistry, physics, and materials science expertise, ensuring precise FTIR spectral analysis and interpretation. Covalent delivers insights beyond the raw data, from routine screening to advanced surface chemical analysis.
Every project receives individual attention, from method selection to final reporting, so you get the highest value from your FTIR Analysis Services.