Concentration-modulated absorption spectroscopy. Lifetime measurements of the 2E state of Cr3+ in a ruby crystal

Abstract

The quantitative pump–probe technique of concentration-modulated absorption spectroscopy is employed to measure the concentration of the Cr³⁺ ion in a ruby crystal. A previously developed theory, confirmed experimentally in this study, shows how measurements of the fractional power change of a probe laser at various frequencies of modulation of pump laser can provide information on state lifetimes of absorbing chromophores. The measured lifetime of the ²E state of Cr³⁺ in the crystal (2.9 ms) is used with absorbance data to provide a direct measure of the Cr³⁺ concentration in the crystal.