  Fourier transform infrared (FTIR) spectrometers have been the dominant
technology in the field of mid-infrared (MIR)spectroscopy for decades.
Supercontinuum laser sources operating in the MIR spectral region now offer the
potential to enrich the field of FTIR 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 MIR supercontinuum sources to FTIR 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 FTIR 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 FTIR spectrometer was tested for a concentration series of
aqueous formaldehyde solutions in a liquid flow cell (500 $\mu$m path length)
and compared with the conventional FTIR (130 $\mu$m 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, FTIR spectrometers
equipped with novel broadband MIR 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.
