An improved microstrip plasma for optical emission spectrometry of gaseous species

摘要

A modified ocmpact 2.45 GHz microstrip plasma (MSP) operted with Ar as working gas atmospherric pressure has been characterized and examined for its suitability for the determination of Hg as gaseous species by optical emission spectrometry.As a formerly described MSP the new device is provided on a sapphre substrate.tehareas of plasma stability in terms of gas flow rates and microwave power for both MSPs with respect to plasma form and reflected power were investigated.Power levels of 5-40 W and Ar flow rates of 15-60 l/h were used.The modified MSP,which extends out of the cannel in the sappire substrate,was used for the recording of emission spectra for Hg vapor at different working conditions.Using optimized parameters a detection limit for Hg ofless than 10 ng Hg/l Ar is botained.The attainable excitaiton temperatures in teh modified MSP at different microwave power were determined under the use of Fe as thermometric species and introducing ferrocene into the plasma.They were found to be at the order of 6000-7000 K for a power of 10-40 W and a gas flow of 15 l/h.It was shown that the modified MSP source can be combined with both a conventional monochromator with photomultiplier detection and a miniaturized spectrometer with CCD detection,whereby space-angle limitations are nto stringent.