Fourier Transform Infrared Spectroscopy (FTIR)

Fourier Transform Infrared Spectroscopy (FTIR) is a powerful analytical technique capable of rapidly identifying the "chemical families" of substances. Typically, organic and polymeric compounds (and to a lesser extent, inorganic compounds) produce unique "fingerprint" infrared spectra that can be compared against EAG's extensive reference database, allowing for the determination of the chemical family or even the exact identity of unknown components.

FTIR is part of the Smart Chart series, as shown above, alongside Raman spectroscopy, which serves as a complementary technique.

FTIR measures infrared light absorbed by a sample and generates spectra based on the functional groups present in the material. In addition to conventional sample preparation methods (such as micro-extraction, dilution, KBr pelletization, and grinding techniques), EAG utilizes various Attenuated Total Reflection (ATR) accessories that enable direct analysis of insoluble or multi-layered samples.

Ideal Applications of FTIR

1. Characterization and identification of complex mixed materials, including gases, liquids, and solids.

2. Detection of organic contaminants (e.g., particles, residues) at both macro and micro scales.

3. Quantification of oxygen (O) and hydrogen (H) in Si wafers, as well as hydrogen (Si-H vs. NH) in SiN, SiON, and a-Si thin films.

Our Strengths

• Ability to identify organic functional groups and often specific organic compounds.

• Extensive spectral libraries for compound and mixture identification.

• Ambient conditions (no vacuum required; suitable for semi-volatile compounds).

• Minimum analysis area: ~15-50 µm. Rule of thumb: If the sample is visible to the naked eye, it can likely be analyzed.

• Quantitative analysis possible with appropriate standards and uniform sample thickness.

• Complements Raman spectroscopy.

Limitations

1. Limited surface sensitivity (typical detection limit is ~100 nm film thickness).

2. Only specific inorganic materials exhibit FTIR spectra (e.g., silicates, carbonates, nitrates, sulfates; not detectable: TiO₂, oxides, etc.).

3. Quantitative analysis requires reference standards.

4. Glass absorbs IR light, making it unsuitable for FTIR analysis.

5. Water strongly absorbs IR light, potentially interfering with the analysis of dissolved, suspended, or wet samples.

6. Simple cations/anions (e.g., Na⁺, Cl⁻) do not absorb IR light and thus cannot be detected.

7. Mixtures/multiple components may require additional lab preparation and analysis.

8. FTIR cannot analyze reflective metals (as they reflect IR light).

FTIR Technical Specifications

• Detected signal: Infrared absorption.

• Detected elements: Molecular functional groups (not individual elements).

• Detection limits:

  • 1-10 wt% (quantitative analysis of known components).

  • 5-20% (identification of unknown components).

• ATR depth profiling: ~0.1-1 µm.

• Transmission FTIR: IR light passes through the entire sample.

• Imaging: FTIR does not perform mapping.

• Lateral resolution/probe size: >15-50 µm.

Conclusion

EAG provides FTIR services to analyze a wide range of materials. Additionally, you can rely on fast turnaround times, accurate data, and one-on-one support to ensure you fully understand the results.