XeCl-laser-generated ablation products from a nitrogen-rich polymer studied by laser-ionization mass spectrometry

Abstract

Laser-ionization time-of-flight mass spectrometry has been used to probe laser-ablation products from a nitrogen-rich polymer at a wavelength of 308 nm. The ablation products at a laser fluence of 150 mJ/cm² showed, similar to 532 nm ablation studied previously [18], two strong peaks due to neutral species that were assigned to C⁺ and CN⁺, as well as several weak peaks that were assigned to CH⁺, HCN⁺, HCNH⁺, H_nN−CN⁺ (n=1–3), and H₂N−C=N−CN⁺ or H₂N−C=N−CN⁺. The ablation products at 870 mJ/cm² revealed, in addition to a broad signal due to ionic products generated directly by the ablation laser, several peaks due to neutral products that were assigned to C⁺, C ⁺₂ , C ⁺₃ , CN⁺, HCN⁺, HCNH⁺, and NCCN⁺. The most probable flight velocities for major neutral products are 5.7×10⁴ cm/s at 150 mJ/cm² and 2.3–2.7×10⁴ cm/s at 870 mJ/cm². The results at a laser fluence of 150 mJ/cm² support the finding that the translational energy of the tragments has importance for the collision-induced product generation in the laser plume, as suggested earlier [18]. Furthermore, the product generation at 870 mJ/cm² is interpreted by the ejection of small neutral and ionic fragments, and subsequent reactions among the fragments.