Elemental composition of ions associated with low mass carbon clusters generated by UV laser ablation of polyimide

Previously, it has been shown that three types of C clusters, characterized by mass range and relative intensities, are produced upon laser ablation of polyimide. The low mass clusters, Cn 9 < n < 25, always appear coincident with peaks 2 amu greater than the bare C cluster. Using perdeuterated polyimide, we have established the elemental composition of these peaks to be predominately, CnH2, rather than Cn-1N, which is allowed since polyimide contains 5 at% N. These results establish the positive ion spectrum of polyimide to be composed of C and H with little contribution from heteroatoms, and show that low mass C clusters preferentially add 2 H atoms in the high energy, multi-element plasma induced by the laser. © 1989.