Analysis of deuteration reactions using self-mixing in a terahertz quantum-cascade laser

We present a THz-QCL spectroscopy technique, for analyzing deuteration reactions in gases. This is an important analytical chemistry technique, underpinning mechanistic studies. We use a self-mixing interferometry approach, in which radiation from a multimode QCL is fed-back into the device, via a gas cell, causing perturbations to the QCL voltage. This enables “detector-free” sensing over a 17-GHz range, allowing speciated measurements of reactions involving H2O, D2O, HDO, CH3OH and CH2DOD.