We have developed a number of Faraday rotation spectrometer technologies for the detection of paramagnetic gas species such as O2, 15NO and 14NO, and OH· radicals. Application of a magnetic field Zeeman-splits the rovibrational molecular states, inducing magnetic circular birefringence and causing linearly polarized light to rotate. Our techniques are capable of measuring polarization rotations of ~ 10-9 rad·Hz-1/2, yielding high-precision trace-gas measurements (parts-per-million to -billion levels). We have investigated a variety of measurement techniques (e.g. static magnetic fields, AC-modulated magnetic fields, dual-modulation schemes, and heterodyne Faraday rotation spectroscopy), with applications ranging from medical studies of human metabolism to nitrogen cycling in the environment.
Projects:
- Cavity-enhanced FRS
- Cavity ring-down FRS
- Dual-comb based FRS
- Static magnetic field FRS with a hybrid detection (hybrid FRS)
- AC-modulated magnetic field (AC-FRS)
- Dual-modulated FRS (DM-FRS)
- Heterodyne-FRS
- Combustion diagnostics: in-situ HO2 radical detection in a photolysis reactor
- Applications
- Environmental Sensing
- Medical Diagnostics
- Combustion Diagnostics
- Sensing Configurations
- Remote Sensing
- Point/Extractive Sensors
- Sensor Networks
- Technologies
- Dual-comb spectroscopy
- Molecular Dispersion Spectroscopy
- Faraday Rotation Spectroscopy (FRS)
- Absorption-Based Spectrometers
- Mid-IR Laser Sources