Honing in on HONO 2 Modeling air pollution requires knowledge of all the interrelated reactions occurring in the atmosphere. Among the most significant is the formation of nitric acid (HONO 2 ) from OH and NO 2 radicals. One sticking point in the study of this reaction has been the uncertainty in how often radicals link through an O-O rather than an O-N bond. Mollner et al. (p. 646 ) measured the partitioning coefficient, as well as the overall consumption rate of the radicals, with an array of highly sensitive spectroscopic techniques in the laboratory. The measurements yielded a well-defined rate constant for nitric acid formation, which was applied to the prediction of ozone levels in atmospheric simulations of the Los Angeles basin.

Graphene quantum dots (GQDs), the zero dimensional (0D) single nanostructures, have many exciting technological applications in diversified fields such as sensors, light emitting devices, bio imaging probes, solar cells, etc. They are emerging as a functional tool to modulate light by means of molecular engineering due to its merits, including relatively low extend of loss, large outstretch of spatial confinement and control via doping, size and shape. In this article, we present a one pot, facile and ecofriendly synthesis approach for fabricating GQDs via pulsed laser irradiation of an organic solvent (toluene) without any catalyst. It is a promising synthesis choice to prepare GQDs due to its fast production, lack of byproducts and further purification, as well as the control over the product by accurate tuning of laser parameters. In this work, the second (532 nm) and third harmonic (355 nm) wavelengths of a pulsed nanosecond Nd:YAG laser have been employed for the synthesis. It has been found that the obtained GQDs display fluorescence and is expected to have potential applications in optoelectronics and light-harvesting devices. In addition, nonlinear optical absorption of the prepared GQDs was measured using the open aperture z-scan technique (in the nanosecond regime). These GQDs exhibit excellent optical limiting properties, especially those synthesized at 532 nm wavelength.

The demand for metallic nanoparticle ornamented nanohybrid materials of graphene oxide (GO) finds copious recognition by virtue of its advanced high-tech applications. Far apart from the long-established synthesis protocols, a novel laser-induced generation of silver nanoparticles (Ag NPs) that are anchored onto the GO layers by a single-step green method named pulsed laser ablation has been exemplified in this work. The second and third harmonic wavelengths (532 nm and 355 nm) of an Nd:YAG pulsed laser is used for the production of Ag NPs from a bulk solid silver target ablated in an aqueous solution of GO to fabricate colloidal Ag-GO nanohybrid materials. UV-Vis absorption spectroscopy, Raman spectroscopy, and TEM validate the optical, structural, and morphological features of the hybrid nanomaterials. The results revealed that the laser-assisted in-situ deposition of Ag NPs on the few-layered GO surface improved its antibacterial properties, in which the hybrid nanostructure synthesized at a longer wavelength exhibited higher antibacterial action resistance to Escherichia coli (E. coli) than Staphylococcus aureus (S. aureus) bacteria. Moreover, nonlinear optical absorption (NLA) of Ag-GO nanohybrid was measured using the open aperture Z-scan technique. The Z-scan results signify the NLA properties of the Ag-GO hybrid material and have a large decline in transmittance of more than 60%, which can be employed as a promising optical limiting (OL) material.

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