Thesis (Ph.D.) - Cairo University - National Institute of Laser Enhanced Science (NILES) - Department of Laser Applicationsin Environmental Metrology, Photochemistry and Agriculture

The present work consists of two parts, in the first part results are presented on the application of standard LIBS and Nanoparticle- Enhanced LIBS (NELIBS) to the classification of igneous and sedimentary rocks.The classification of the obtained spectra was performed using Principal Component Analysis (PCA) and Graph Theory method. The results obtained confirmed the advantages of the LIBS technique in geological applications. As a result excellent classification of the analyzed rocks can be obtained using standard LIBS coupled to Graph Theory analysis, while NELIBS spectra, analyzed with the same technique, provide acceptable results, but with 10% of the spectra not classified. These findings are particularly interesting given the application of the LIBS technique in investigating natural samples having porous and/or rough surfaces.The second part of this study introduces a detailed investigation discriminate between igneous and sedimentary rocks. The used LIBS setup was a conventional single-pulse nanosecond system with an Nd: YAG laser at two excitation wavelengths, 1064 nm and 355 nm. The LIBS spectra of the rock samples were recorded in the 200-700 nm spectral range and normalized to the irradiance for all laser wavelengths to compensate for the different laser pulse energies used.The surface hardness values of the studied samples were spectroscopically determined via the intensity ratios of the ionic - to atomic-spectral lines of iron and magnesium in igneous and sedimentary rock samples. Besides, the laser-induced plasma diagnostics, namely the plasma temperature and the electron density, were calculated from the obtained spectral data

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