XECL-LASER-GENERATED ABLATION PRODUCTS FROM A NITROGEN-RICH POLYMER STUDIED BY LASER-IONIZATION MASS-SPECTROMETRY

Laser-ionization time-of-flight mass spectrometry has been used to pro be laser-ablation products from a nitrogen-rich polymer at a wavelengt h of 308 nm. The ablation products at a laser fluence of 150 mJ/cm(2) showed, similar to 532 nm ablation studied previously [18], two strong peaks due to neutral species that were assigned to C+ and CN+, as wel l as several weak peaks that were assigned to CH+, HCN+, HCNH+, HnN-CN + (n=1-3), and H2N-C=N-CN+ or H2N-C=N-CN+. The ablation products at 87 0 mJ/cm(2) revealed, in addition to a broad signal due to ionic produc ts generated directly by the ablation laser, several peaks due to neut ral products that were assigned to C+, C-2(+), C-3(+), CN+, HCN+, HCNH +, and NCCN+. The most 3 probable flight velocities for major neutral products are 5.7 x 10(4) cm/s at 150 mJ/cm(2) and 2.3-2.7 x 10(4) cm/s at 870 mJ/cm(2). The results at a laser fluence of 150 mJ/cm(2) suppo rt the finding that the translational energy of the fragments has impo rtance for the collision-induced product generation in the laser plume , as suggested earlier [18]. Furthermore, the product generation at 87 0 mJ/cm(2) is interpreted by the ejection of small neutral and ionic f ragments, and subsequent reactions among the fragments.