Femtosecond Laser-Induced Plasma Spectrometry of Bimetallic Noble Metal Catalysts.

Femtosecond laser-induced breakdown spectroscopy (LIBS), a powerful and versatile multi-elemental analysis technique, is employed for quantification of noble metal catalysts (Pt-Pd) loaded on cordierite matrix. The laser-induced plasma was generated on the sample surface using 1 mJ energy from a 50 fs, 1 kHz, Ti-Sa laser system. The spectral emission of the cordierite matrix and noble metals are systematically studied to identify 270.23 nm and 340.42 nm lines for quantitative estimation of Pt and Pd, respectively. Quantification of the LIBS signal is further aided by measurement of excitation temperature and electron density of the laser-ablated plasma. Time-resolved LIBS is used under optimized conditions to evaluate the analytical predictive ability of the technique. Calibration curves for Pt and Pd exhibit good linearity. The limit of detection for Pt and Pd is estimated to be 55 µg/g and 17 µg/g, respectively, of the cordierite matrix.