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Intrinsic chiral discrimination via terahertz absorption circular dichroism
Hyeji Son1, Sujeong Park1, Miso Lee1
1Department of Physics, University of Ulsan, Ulsan 44610, Republic of Korea.
The Journal of Chemical Physics
|October 2, 2025
Summary
This study introduces a new terahertz (THz) chiral sensing method using absorption differences, overcoming limitations of traditional transmission-based circular dichroism (CD) measurements for identifying chiral molecules.
Area of Science:
- Spectroscopy
- Chiroptics
- Terahertz (THz) Science
Background:
- Terahertz (THz) circular dichroism (CD) measurements face challenges with weak signals and signal distortion in lossy media.
- Existing transmission-based THz-CD methods are limited by severe signal attenuation and spectral distortion.
Purpose of the Study:
- To develop an alternative THz-CD approach for robust chiral molecule identification.
- To retrieve helicity-dependent absorption coefficients from complex transmission functions.
Main Methods:
- Utilized polarization-resolved THz time-domain spectroscopy to obtain complex transmission functions.
- Extracted absorption-resolved CD signals by analyzing differences in absorption spectra for circularly polarized THz waves.
- Validated the method with glucose and tartaric acid enantiomers.
Main Results:
- Successfully obtained distinct absorption-resolved CD spectral signatures for glucose and tartaric acid enantiomers.
- Observed spectral features at 1.45 THz (glucose) and 1.1 THz (tartaric acid) corresponding to molecular resonances.
- Demonstrated superior sensitivity compared to transmission-based CD measurements.
Conclusions:
- The absorption-based THz-CD method provides a robust, label-free, and quantitative platform for chiral sensing.
- This technique is applicable to pharmaceutical analysis, biochemical diagnostics, and molecular spectroscopy.
- The method enhances the observability of spectral signatures obscured in transmission measurements.
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