High Resolution Gas Phase Spectroscopy with a Quantum Cascade Laser at 2.5 THz

We have performed high resolution spectroscopy of rotational lines of
¹²
CH
₃

¹⁶
OH in a THz spectrometer based on a 2.5 THz distributed feedback quantum cascade laser (QCL). The absolute frequency was determined simultaneously with the absorption measurement by mixing part of the radiation from the QCL with the radiation from a THz gas laser in a Schottky diode.