Sensitive detection of acetylene absorption in the visible by using a stabilized AlGaAs diode laser

Overtone transitions of C2H2 at ~789 nm are investigated by means of an AlGaAs laser operating in an external optical cavity configuration. Relative amplitude noise is of a few parts in 106 (ppm) and permits an absorption detection limit of 0.2 ppm/km. Self-broadening and air broadening is measured for two components of the observed band [P(11) at 12646.966 and R(5) at 12688.699 cm−1].