[Zurück]

I. Zorin, J. Kilgus, K. Duswald, B. Lendl, B. Heise, M. Brandstetter:
"Sensitivity-Enhanced Fourier Transform Mid-Infrared Spectroscopy Using a Supercontinuum Laser Source";
Applied Spectroscopy, 74 (2020), 4; S. 485 - 493.

Fourier transform infrared (FT-IR) spectrometers have been the dominant technology in the field of mid-infrared (mid-IR)
spectroscopy for decades. Supercontinuum laser sources operating in the mid-IR spectral region now offer the potential to
enrich the field of FT-IR spectroscopy due to their distinctive properties, such as high-brightness, broadband spectral
coverage and enhanced stability. In our contribution, we introduce this advanced light source as a replacement for
conventional thermal emitters. Furthermore, an approach to efficient coupling of pulsed mid-IR supercontinuum sources
to FT-IR spectrometers is proposed and considered in detail. The experimental part is devoted to pulse-to-pulse energy
fluctuations of the applied supercontinuum laser, performance of the system, as well as the noise and long-term stability.
Comparative measurements performed with a conventional FT-IR instrument equipped with a thermal emitter illustrate
that similar noise levels can be achieved with the supercontinuum-based system. The analytical performance of the
supercontinuum-based FT-IR spectrometer was tested for a concentration series of aqueous formaldehyde solutions in
a liquid flow cell (500 mm path length) and compared with the conventional FT-IR (130 mm path length). The results show
a four-times-enhanced detection limit due to the extended path length enabled by the high brightness of the laser.
In conclusion, FT-IR spectrometers equipped with novel broadband mid-IR supercontinuum lasers could outperform
traditional systems providing superior performance, e.g., interaction path lengths formerly unattainable, while maintaining
low noise levels known from highly stable thermal emitters.

Mid-infrared spectroscopy, mid-IR, supercontinuum laser source, Fourier transform infrared spectroscopy, FT-IR

http://dx.doi.org/10.1177/0003702819893364