Quartz-enhanced photoacoustic spectroscopy

A new approach to detecting a weak photoacoustic signal in a gas medium is described. Instead of a gas-filled resonant acoustic cavity, the sound energy is accumulated in a high-$Q$ crystal element. Feasibility experiments utilizing a quartz-watch tuning fork demonstrate a sensitivity of $1.2\times {10}^{-7} {\mathrm{cm}}^{-1} \mathrm{W}/\sqrt{\mathrm{Hz}}$. Potential further developments and applications of this technique are discussed.