Observation of the frequency dependence of ICP radiation noise

Abstract
Radiation noise power spectra were measured at frequencies from 20 Hz up to 3 kHz in high-frequency inductively coupled plasma (ICP). Aerosol sample radiation excess noise compared to that of argon radiation at frequencies of about 2 kHz and lower was observed. This excess noise is interpreted as a modulation of the radiation intensity by evaporating aerosol droplets. Further understanding and measurements of the noise spectra can be useful in both sample flow and droplet evaporation rate studies and analysis of possible ways to reduce ICP sample radiation or fluorescence detection limits.