Patent ID: 8581180
Filing Date: 2013-11-12
Classification: H01J

Abstract:
1. A method for the measurement of a solid sample by pulsed glow discharge spectrometry, comprising: a) applying a pulsed RF electric field at the terminals of the electrodes of a glow discharge lamp in the presence of a carrier gas and a sample to be analysed, said lamp being electrically coupled to an impedance matching device having a variable electric impedance Ω, so as to generate a pulsed glow discharge plasma, the duration of an electric pulse being equal to τ b) measuring by mass spectrometry at least one signal representative of a ionised species having a predetermined m/z ratio, said measurement being carried out at an acquisition frequency F c) measuring a signal representative of an impedance mismatch ΔΩ between a pulsed RF electric field generator and electrodes of the discharge lamp during at least one part of the plasma pulses using a fast measurement acquisition system synchronised with said pulses, said fast acquisition system having an acquisition frequency F d) determining an impedance variation dΩ to be applied to the impedance matching device as a function of the measurement of a signal representative of the impedance mismatch ΔΩ; e) modifying the impedance Ω of the impedance matching device as a function of the value of dΩ determined at step d); f) repeating steps c) to e) so as to minimize the impedance mismatch ΔΩ.