Atmospheric applications IFS 125HR

Importance of the Topic

The analysis of atmospheric trace gases is critical for understanding environmental changes, air quality dynamics and climate processes. High-resolution Fourier transform infrared (FT-IR) spectroscopy enables precise detection and quantification of key pollutants and trace species in various atmospheric layers.

Objectives and Study Overview

This application note demonstrates the versatility of the Bruker IFS 125HR spectrometer in atmospheric research. Two field installations are presented: one at the Shenzhen Meteorological Bureau, employing three spectrometers for simultaneous mid-IR to UV observations, and a polar night deployment utilizing solar and lunar absorption techniques.

Methodology and Instrumentation

The IFS 125HR interferometer features a permanently aligned cube corner Michelson design, ensuring beam integrity, sensitivity and long-term stability without active realignment. Dual-channel DigiTect™ detection and modular optics enable parallel acquisition across broad spectral ranges.

Instrumentation

• IFS 125HR high-resolution FT-IR spectrometer
• A547N/2 solar tracker with CamTracker image processing software
• 3×120° reflective beamsplitter for distribution to multiple inputs
• Dichroic optical components and optimized detectors for MIR, NIR and VIS/UV ranges

Main Results and Discussion

In Shenzhen, three compact IFS 125HR units recorded atmospheric spectra from 600 to 33 000 cm⁻¹ in parallel, observing solar absorption to detect human-made pollutants and background signals from sea and urban atmospheres. During polar night campaigns, the system acquired high-resolution lunar absorption spectra, capturing seasonal cycles of stratospheric species such as HNO₃, HCl, HF and ClONO₂ with 0.02 cm⁻¹ resolution.

Benefits and Practical Applications

• Unparalleled flexibility for continuous, multi-range atmospheric monitoring
• High sensitivity and resolution for trace gas quantification
• Parallel data acquisition reduces measurement time and instrument reconfiguration
• Applicability to remote and low-signal environments, including polar regions

Future Trends and Potential Applications

Advances in detector technologies and real-time data processing will further enhance remote sensing capabilities. Integrating FT-IR systems with unmanned platforms and satellite validation efforts can expand spatial coverage. Emerging applications include greenhouse gas flux monitoring, volcanic emission studies and urban air quality networks.

Conclusion

The IFS 125HR demonstrates exceptional performance and adaptability for high-resolution atmospheric trace gas studies. Its stable interferometer, dual-channel detection and modular optics facilitate comprehensive environmental monitoring across diverse conditions, from urban skies to polar night.

References

• M. Gisi, et al., CamTracker: a new camera controlled high precision solar tracker system for FT-IR spectrometers, Atmos. Meas. Tech., 4 (2011), p. 47–54.
• J. Notholt, O. Schrems, Ground-based FT-IR spectroscopic absorption measurements of stratospheric trace gases in the Arctic with the sun and the moon as light sources, J. Mol. Structure, Vol. 347 (1995), p. 407–416.
• N. M. Deutscher, et al., Total column CO₂ measurements at Darwin, Atmos. Meas. Tech., 3 (2010), p. 947–958.
• R. Kohlhepp, et al., Observed and simulated time evolution of HCl, ClONO₂, and HF total column abundances, Atmos. Chem. Phys., 12 (2012), p. 3527–3556.