Correlation between theoretical and experimental atom-ion, ion-ion analytical curves in spectral analysis

Abstract

A theoretical expression for the analytical curve used in emission spectral analysis is derived assuming local thermal equilibrium in the are plasma in air at atmospheric pressure. Correlation between the theoretical curve and the experimental analytical curve constructed using ion-ion, atom-atom, atom-ion line pairs of the elements cobalt-beryllium is carried out. A close agreement is found for ion-ion, atom-ion line pairs and less for atom-atom line pair.Terminology:I: Intensity of the analysis spectral linec: Concentration of the element in the sampleN: Total density of the element in the dischargeN _a: Density of neutral atoms of element in the dischargeN _i: Density of singly charged ions of element in the dischargeA=A _qp: Einstein transition probability for theq top transitiong, g’: Statistical weights of statesp andq, respectivelyQ Total partition function of elementv: Frequency of the emitted lineE=E _q: Energy of higher stateq V=V _q: Excitation potential of the spectral linev _qp expressed in electron voltsα: Degree of ionization of atoms of elementT: Average gas temperature in degrees Kelvin of the emission regionV _i: Ionization potential of the elementP _e: Electron pressure of the arc plasma expressed in atmospheresn: Self absorption parameterk: Boltzmann’s constant

It is to be noted that the subscript (r) denotes the terminology corresponding to that of the internal reference element.