Continuous-wave cavity ringdown for high-sensitivity polarimetry and magnetometry measurements.

Area of Science:

• Physical Chemistry
• Spectroscopy
• Analytical Chemistry

Background:

• Chiroptical activity measurements are crucial for understanding molecular structure and interactions.
• Cavity ringdown polarimetry offers high sensitivity but requires advanced methodologies for precise measurements.
• Existing techniques may face limitations in sensitivity or applicability to various phases.

Purpose of the Study:

• To develop a novel continuous-wave laser-based cavity ringdown polarimetry variant.
• To achieve highly precise chiroptical activity and magnetometry measurements.
• To demonstrate the method's capability in evaluating Verdet constants and optical rotations of chiral molecules in different phases.

Main Methods:

• Utilized a continuous-wave laser at 532 nm for cavity ringdown polarimetry.
• Employed external modulation of laser frequency to probe non-degenerate left- and right-circularly polarized cavity modes.
• Applied the technique to measure Verdet constants of CeF3 and fused silica, and optical rotations of gas- and solution-phase chiral molecules.

Main Results:

• Successfully evaluated Verdet constants for crystalline CeF3 and fused silica.
• Determined optical rotations for gas-phase α-pinene and R-(+)-limonene vapors.
• Quantified optical rotations for solution-phase D-glucose and L-histidine, achieving high detection sensitivities.

Conclusions:

• The novel cavity ringdown polarimetry variant enables precise chiroptical activity measurements across different molecular phases.
• The method's sensitivity is suitable for detecting subtle optical rotations in both gaseous and liquid samples.
• Experimental results for R-(+)-limonene optical rotation were rationalized through quantum chemistry computations, validating the technique's accuracy.