Identification of Limiting Noise Sources in the Microwave-Induced Nitrogen Discharge at Atmospheric Pressure

Abstract

The noise from the emission signal of the microwave-induced nitrogen discharge at atmospheric pressure (MINDAP) has been analyzed. Wavelength-scan flicker-ratio, precision measurements, time-trace correlation and noise amplitude spectra were used to determine the individual components of the system noise. Noise spectra are reported with the use of a nebulizer sample introduction system for desolvated and undesolvated aerosol, for varying analyte concentration, and for background emission from nitrogen and water vapor. The analytical system appears to be flicker-noise-limited below about 1 Hz for all measurements made. Only 60 and 120 Hz peaks are detected in the frequency region extending to 700 Hz, and presumably arise from the microwave power supply