AIMsight™ Infrared Microscope & AIRsight™ Infrared/Raman Microscope

Importance of the Topic

Infrared microscopy serves as a powerful tool for non-destructive chemical analysis at the micrometer scale. It is widely used in materials science, quality control, forensic investigations, and pharmaceutical research to identify molecular fingerprints. Traditional cryogenically cooled detectors require liquid nitrogen, increasing operational complexity and cost. Introducing a Peltier-cooled MCT detector simplifies workflows by eliminating the need for liquid nitrogen while preserving high sensitivity.

Objectives and Study Overview

This whitepaper presents the integration of a thermoelectrically cooled mercury cadmium telluride (TEC MCT) detector into Shimadzu’s AIMsight™ and AIRsight™ infrared microscopes. Key goals include:

• Enabling infrared measurements of sub-50 µm samples without liquid nitrogen.
• Comparing performance with standard T2SL (liquid-nitrogen cooled) and DLATGS (room-temperature) detectors across different sampling modes.
• Demonstrating practical sensitivity, scan time, and spectral range trade-offs.

Methodology

Comparative experiments were conducted in transmission, reflection, and attenuated total reflection (ATR) modes. Polypropylene resin in a diamond cell, board terminal adhesions, and silicone rubber samples served as test materials. Aperture sizes ranged from 25 × 25 µm to 200 × 200 µm. Scan counts and durations were adjusted to evaluate signal-to-noise ratios for each detector type under identical optical configurations.

Instrumentation Used

• AIMsight™ Infrared Microscope
• AIRsight™ Infrared/Raman Microscope
• IRXross™ Fourier Transform Infrared Spectrophotometer
• Detectors:
  • T2SL (liquid nitrogen cooled, 10 × 10 µm minimum aperture)
  • TEC MCT (Peltier-cooled, 25 × 25 µm minimum aperture)
  • DLATGS (room-temperature, 100 × 100 µm minimum aperture)
• Diamond compression cell for transmission
• ATR accessory for surface-sensitive measurements

Main Results and Discussion

Transmission measurements of automotive polypropylene-TALC resin showed the TEC MCT detector achieves comparable sensitivity to the T2SL when using 25 × 25 µm apertures—without liquid nitrogen—with moderate noise increase offset by extended scan times (500 scans in 140 s). DLATGS required larger apertures (100 × 100 µm) and longer scans due to lower sensitivity but provided data down to 400 cm−1.

In reflection mode on board terminal adhesions (30 × 40 µm), the TEC MCT delivered S/N ratios similar to the T2SL after extended acquisition, confirming its suitability for surface analyses without cryogens.

ATR measurements of silicone rubber highlighted that larger apertures (200 × 200 µm) improve sensitivity. The TEC MCT again matched T2SL performance when scan parameters were optimized.

Benefits and Practical Applications

• Eliminates liquid nitrogen handling, reducing safety concerns and operational costs.
• Maintains high sensitivity for micron-scale samples, supporting forensic trace analysis and semiconductor inspection.
• Easy detector switching via software allows rapid adaptation to sensitivity or spectral range requirements.
• Applicable in QA/QC laboratories, materials research, and environmental monitoring where simplified workflows are critical.

Future Trends and Applications

Advancements in detector cooling technology and signal-processing algorithms will further enhance room-temperature detector sensitivity. Emerging applications may include:

• Three-dimensional chemical imaging in microelectronics and tissue samples.
• Real-time in situ monitoring of chemical reactions and degradation processes.
• Integration with machine-learning models for automated spectral interpretation.
• Combined IR-Raman multimodal microscopy for comprehensive molecular profiling.

Conclusion

The TEC MCT detector option for Shimadzu’s infrared microscopes bridges the gap between cryogenic and room-temperature performance. By providing near-cryogenic sensitivity without liquid nitrogen, it streamlines micro-infrared analysis across transmission, reflection, and ATR modes, making high-precision chemical characterization more accessible and cost-effective.

References

No formal literature references were provided in the source document. Shimadzu application note C103-E153 (First Edition January 2025) served as the basis for this summary.