We present an overview of incoherent broadband cavity-enhanced absorption spectroscopy (BBCEAS) and discuss its relevance to monitoring atmospherically important gases. Adavantages of the method include its high sensitivity, portability, and good spatial resolution. We present the visible absorption spectra of NO<sub>2</sub> and NO<sub>3</sub> between 600 nm and 720 nm and address issues relating to spectral deconvolution and the simultaneous measurement of multiple gases. The sensitivity of our system is compared to that of other trace gas detection techniques.
We report the synthesis of silver nanoparticles by laser ablation of the bulk material in water and five other organic solvents employing a frequency doubled Nd:YAG laser at 532 nm. The colloidal suspensions were characterized by means of UV/VIS absorption spectroscopy and transmission electron microscopy. The reproducibility of the particles' size distribution and yield, which strongly depends on the solvent and the ablation condition, is critically reviewed. The agglomeration behaviour of silver particles was investigated as a function of temperature. The unusual role of water in the ablation process and upon agglomeration will be discussed.