Determination of Chromium Traces by Atomic Ionization Spectroscopy in Aqueous Reference Solutions and Gallium Arsenide Using a Rod–Flame Atomizer

Abstract—The present study is dedicated to determining trace amounts of chromium in its aqueous reference solutions and in high-purity gallium arsenide using atomic ionization spectroscopy. Single- and two-step excitation schemes for chromium atoms from the ground state 3d54s 7S3 to the septet states 3d54p 7P2,3,4, 3d44s4p 7P2,3,4 were studied using a rod–flame atomizer. The formation mechanism of the atomic ionization signal for the two-step excitation scheme was established. The most efficient two-step excitation schemes were found to be λ1 = 425.4 nm, λ2 = 451.4 nm and λ1 = 425.4 nm, λ2 = 426.1 nm, corresponding to a detection limit for chromium of 50 pg/mL. The possibility of determining trace amounts of chromium in gallium arsenide using the rod–flame atomizer at a level of 5 × 10–7% was demonstrated. Two methods to enhance the selectivity and sensitivity of atomic ionization determination of chromium were proposed: optimization of the temperature program of the rod–flame atomizer and the use of two-step excitation of chromium atoms. It was shown that the main interfering factor is the background associated with matrix ionization. Methods to reduce or eliminate matrix effects were proposed, ensuring direct determination of elements in samples.