REMOVAL OF AIR INTERFERENCE IN LASER-INDUCED BREAKDOWN SPECTROMETRY MONITORED BY SPATIALLY AND TEMPORALLY RESOLVED CHARGE-COUPLED-DEVICE MEASUREMENTS

Laser-induced breakdown spectrometry is a suitable method for the dire ct in-process measurement of materials composition. The emission spect rum from the plasma includes information not only on the analysis area but also on the surrounding atmosphere, mainly lines corresponding to O, N and C if the experiments are being carried out in air at atmosph eric pressure. These emission lines could interfere with the sample sp ectrum. Although working under vacuum conditions or the use of control led atmospheres can be considered to be the best choice, in most pract ical applications working in air at atmospheric pressure is the common way of analysis. A study was undertaken to evaluate the removal of ai r interferences in poly(methyl methacrylate) samples by using the temp oral and spatial resolution of gated charge-coupled devices, without a ny sample treatment or alteration of the experimental set-up.