Spatially resolved molecular information on galena (PbS) crystals was obtained by microspectrometric Raman mapping through a high numerical aperture objective. Different experimental conditions were used: excitation wavelength, excitation power, crystal size and temperature. Spatially guided analysis was obtained from the spectra recorded in the point-by-point microprobe mapping mode with 1 µm spacing between the points. Multivariate data processing yielded the typical spectra of PbS and its degradation products. The Raman features of PbS were found to be weak under non-damaging excitation conditions. The laser-damaging effect generates complete and irreversible oxidation of PbS to α-PbO for particles of size of the order of micrometres. For larger PbS crystals, several lead oxysulphates including 4PbO·PbSO4 and 3PbO·PbSO4 were located in the vicinity of the illuminated spot by Raman mapping.
No takes yet. Share an insight, caveat, or question.
Batonneau et al. (2000) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: