NapI/PMMA, laser-induced fluorescence

This possibility is indicated in the study of the ablation of PMMA and PS doped with haloaromatic compounds (iodonaphthalene (NapI), iodo-phenanthrene (PhenI)). Experimentally these dopants offer the advantage that they exhibit negligible fluorescence, whereas their products are moderate or strong emitters. Thus, product formation can be conveniently monitored via laser-induced fluorescence (LIF). It is noted that the study has focused on the characterization of the species/products that remain in the substrate upon ablation. Thus, the experiment is of the pump-probe type, in which pump pulses at a particular wavelength (2=308, 248 or 193 nm) are used to irradiate the films, and laser pulses of very low fluence are employed to induce photoproduct fluorescence (FLaser<3 mj cm-2, probing effected always at 2=248 nm). Detailed information on the experimental setup and procedures is provided elsewhere [83-85]. 

Fig. 11 Laser-induced fluorescence spectra recorded from Napl-doped PMMA samples (1.2 wt%) after their irradiation with a single pump pulse at 248 nm at laser fluences below a, and above b the corresponding ablation thresholds. For comparison purposes, the spectra have been scaled. The figure also illustrates the approximate deconvolution of the probe spectrum into the emission bands of the suggested species (the Nap2 spectrum is recorded in the photolysis of high-concentration NapI solution, while the NapH/PMMA spectrum is recorded from PMMA doped with 0.08 wt% NapH)...

Fig.14 NapH-like photoproduct laser-induced fluorescence intensity as a function of the delay time between the pump and the probe beams in the 248 nm irradiation of NapI/ PMMA films (0.8 wt%) (kinetics characteristic of irradiation at weakly absorbed wavelengths)...

Fig. 16 Laser-induced fluorescence spectra recorded from NapI/PMMA (0.4 wt%) irradiated with the indicated number of pulses (at 248 nm) at the two indicated fluences...

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See also in sourсe #XX -- [ ]

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