Laser-induced photothermal displacement spectroscopy (LIPDS) for speciation of lanthanides and actinides

We have developed a novel photothermal spectroscopy, named laser-induced photothermal displacement spectroscopy (LIPDS), having characteristics of high sensitivity, non-contact detection, remote and easy operation by using an optical heterodyne interferometer as a detection tool. The LIPDS system was constructed using a Nd:YAG laser pumped tunable dye laser and an interferometer. Optimal conditions for the measurement have been studied using lanthanide and actinide ions. By experiments, it was verified that the principle of LIPDS is based on the following processes: generation of an acoustic wave by absorption of light, vibration of a sample cell induced by propagation and reflection of the acoustic wave, and detection of the vibrational displacement of the cell by an optical heterodyne interferometer. For demonstration absorption spectra of different metal ions in aqueous solution were measured by the system. The LIPDS system is applicable for quantitative detection and speciation of the ions with the detection limit of absorptivity down to 3 x 10-4 cm-1. (orig.)