| abstract |
Methods and systems for the quantitative and qualitative determination of one or more exogenous substances within a material are described. A flow of fluorescence-exciting/ablative energy (e.g., laser pulse(s), preferably in the ultraviolet region (e.g. 193-nm)), is directed onto the material to ablate a thin layer (e.g. ≈0.3-μm) of the material using photochemical decomposition. Simultaneously, the laser energy induces the fluorescence of the substance(s) of interest within the ablated layer of the material. The fluorescence emitted by the substance(s) of interest is then received by a device (e.g., a spectrometer), which measures the spectrum (i.e. intensity versus wavelength) of the received fluorescence. The fluorescence spectra are then transmitted to a spectral processing device (e.g., a microprocessor or computer) which is programmed or otherwise adapted to determine, on the basis of the fluorescence spectra, whether the substance(s) of interest is/are present in the material and/or the concentration at which the substance(s) of interest is/are present in the material. This process may be repeated for each layer of the material to determine the concentration gradient of the substance(s) of interest in the material. |