Sub-Doppler diode laser saturated absorption spectroscopy of barium in a low-pressure graphite furnace

As a first step toward developing an optical isotope abundance measurement technique, sub-Doppler saturated absorption spectroscopy has been demonstrated by using a scanning diode laser as a tunable light source and a low-pressure graphite furnace for sample atomization. Spectral linewidths were reduced by a factor of 49 from the pressure-broadened, Doppler-limited value of 2.8 GHz to 57 MHz. This reduction in linewidths was accompanied by a 60-fold increase in detection limits, mainly due to increased loss of analyte through rapid diffusion at the low pressure used to minimize collisional broadening. Some residual homogeneous broadening was observed, which is primarily attributed to laser power broadening. copyright 1998 Society for Applied Spectroscopy