Approaching Single Atom Detection with Atomic Fluorescence in a Glow Discharge Atom Reservoir

A COMMERCIAL HOOLOW CATHODE LAMP IS USED AS AN ATOM RESERVOIR FOR THE ATOMIC FLUORESCENCE OF LEAD EXCITED BY A COPPER LASER- PUMPED DYE LASER. THE GLOW DISCHARGE SOURCE IS NEARLY AN IDEAL ATOM RESERVOIR FOR SUCH MEASUREMENTS, HAVING VERY LOW BACKGROUND EMISSION AND EXCELLENT ATOMIZATION CHARACTERISTICS. A DETECTION LIMIT OF 1.8 AG OF LEAD WITHIN THE LASER BEAM WAS EASILY OBTAINED. THIS WOULD CORRESPOND TO A NUMBER OF LEAD ATOMS IN THE PROBING VOLUME OF THE ORDER OF 6000, AND COULD BE LOWERED TO ABOUT 1000 IF THE EXTRINSIC CAUSES OF NOISE (LASER SCATTERING, LAMP EMISSION) COULD BE ELIMINATED. BY PULSING THE GLOW DISCHARGE, AND MEASURING BETWEEN PULSES, IT IS FELT THAT SUCH LIMIT COULD INDEED BE REACHED.NA-NOT AVAILABL