Endoscopic Fourier-transform infrared spectroscopy through a fiber microprobe

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Materials Science

Background:

• Fourier-transform infrared spectroscopy (FTIR) is crucial for chemical identification and quantification.
• Quantifying analytes in liquids using FTIR is challenging due to strong IR absorption by the solvent.
• Existing FTIR methods struggle with in-situ analysis within bulk liquid media.

Purpose of the Study:

• To develop an IR fiber microprobe for endoscopic FTIR analysis in liquid solutions.
• To overcome the limitations of traditional FTIR in quantifying analytes within IR-absorbing media.
• To enable point-of-interest chemical profiling within bulk liquids.

Main Methods:

• Development of an infrared fiber microprobe for insertion into liquid samples.
• Measurement of IR transmittance through bulk water using the microprobe.
• Analysis of vibrational modes, transmittance profiles, and absorption coefficients.
• Benchmarking the endoscopic FTIR method by varying probe-substrate distance.

Main Results:

• The IR fiber microprobe successfully obtained full FTIR spectra from within a liquid medium.
• Measurements of water's IR transmittance and absorption coefficients validated the method.
• The endoscopic approach provided micro-sectioned IR transmittance spectra.
• Results were consistent with known IR absorption properties of water.

Conclusions:

• The developed IR fiber microprobe enables endoscopic chemical profiling in bulk liquid solutions.
• This technique overcomes significant limitations of conventional FTIR for liquid analysis.
• The method holds promise for diverse applications in biological, chemical, and electrochemical systems.