The modified Beer—Lambert law and the curve of growth for the atomic resonance transition Sn(6s( 3P o1) ← 5p 2( 3P 0))

Abstract

We present a detailed study of the curve of growth for the resonance transition of ground state atomic tin Sn(6s( 3P o 1) → 5p 2( 3P 0)) at λ = 286.3 nm. An experimental curve of growth is reported from resonance absorption measurements for the λ = 286.3 nm transition on atomic tin vapour in equilibrium with solid tin in the temperature range T = 943–1238 K obtained using the method of phase sensitive detection. Expressing the extent of resonance absorption by the modified Beer—Lambert law ▪ or ▪ the logarithmic form of the experimental curve of growth yields γ = 0.65 ± 0.02. This is found to be in good agreement with previously determined empirical calibrations for this transition derived from time-resolved resonance absorption measurements (γ = 0.64 ± 0.09 and γ = 0.66 ± 0.03). Curve of growth calculations, including the effects of nuclear hyperfine interaction, using the three-layer model are found to be unable to generate departures of this magnitude from the standard Beer-Lambert law employing sensible parameters in the model. This is entirely in accord with previous results of similar measurements on the resonance transition Pb(7s( 3P o 1) ← 6p 2( 3P 0)) at λ = 283.3 nm.