Measuring Solute Concentration with Terahertz Time-Domain Spectroscopy in Single and Multiphase Systems

Area of Science:

• Physical Chemistry
• Materials Science
• Spectroscopy

Background:

• Terahertz time-domain spectroscopy (THz-TDS) is a powerful tool for probing molecular dynamics and material properties.
• Accurate temperature and concentration measurements are crucial for understanding liquid and semicrystalline systems.
• Existing methods may have limitations in simultaneously assessing temperature, concentration, and local variations in complex systems.

Purpose of the Study:

• To develop a versatile microfluidic platform for terahertz time-domain spectroscopy investigations of liquid samples.
• To establish a novel method for simultaneous temperature and concentration calibration of liquid samples at terahertz frequencies.
• To extend the application to study local concentrations within semicrystalline systems and calculate equivalent solute concentrations during crystallization.

Main Methods:

• Utilized a microfluidic platform integrated with terahertz time-domain spectroscopy.
• Developed a calibration method for temperature and concentration using THz-TDS.
• Analyzed absorption spectra at low frequencies to determine equivalent solute concentration during crystallization.

Main Results:

• Demonstrated a versatile setup for THz-TDS analysis of liquids across various temperatures.
• Successfully implemented a novel method for accurate temperature and concentration calibration of liquid solutions.
• Enabled the study of local concentrations in semicrystalline systems and the calculation of equivalent solute concentration during crystallization, exemplified by the MgSO4-water system.

Conclusions:

• The developed microfluidic THz-TDS setup offers a versatile approach for characterizing liquid and semicrystalline systems.
• The novel calibration method provides accurate temperature and concentration determination at terahertz frequencies.
• This technique opens new avenues for investigating complex phase transitions and local concentration dynamics in materials science.