Thermal lensing spectrophotometry of uranium (VI) with pulsed laser excitation

Abstract

A double-beam thermal lensing experiment based upon a pulsed dye laser as the excitation beam and a He-Ne laser as a probe beam is described. The technique has been used to detect the small absorptions given by uranyl ions in aqueous solution. The system is capable of detecting absorption coefficients as low as 5 × 10^–7 cm^–1. Moreover, by changing several dyes, an absorption spectrum can be obtained at concentration levels (ca. 4 × 10^–6M) far below (ca. 10³×) those obtained by conventional absorption spectrophotometry, thereby allowing the direct study of the chemical equilibria involved. The sensitivity of the present apparatus is limited by short-term fluctuations of the probe laser.