Mid-infrared spectroscopy of liquids by using a modified button sample holder

Area of Science:

• Analytical Chemistry
• Spectroscopy

Background:

• Mid-infrared spectroscopy is crucial for chemical analysis.
• Traditional methods like transmission and ATR have limitations for certain sample types.

Purpose of the Study:

• To introduce a new method for mid-infrared spectroscopy of liquids using a modified button sample holder.
• To evaluate the performance of this new technique for analyzing liquid samples.

Main Methods:

• Utilizing a modified button sample holder with a reservoir for thin liquid layers.
• Employing a praying mantis diffuse reflection optical system for spectral acquisition.
• Adjusting infrared radiation absorption path lengths by varying liquid volume.

Main Results:

• Thin film transflection spectra closely resemble transmission spectra.
• Thicker liquid layers show increased relative intensities for low absorptivity peaks.
• Transflection spectra maintain overlapping peak profiles for high absorptivity bands due to dynamic range effects.

Conclusions:

• The button sample holder provides a complementary technique to transmission and ATR.
• This method is particularly effective for analyzing thick samples and high absorptivity bands.
• Linear calibration plots are achievable for quantitative analysis.