Nick Lockyer oral presentation (PB2-Thu3-2-3)
Femtosecond Laser Post-Ionisation of Drug Molecules
University of Manchester, Oxford Rd, M13 9PL Manchester, United Kingdom
By decoupling the desorption and ionisation steps, laser post-ionisation offers a route to enhanced sensitivity and reduced matrix ionisation effects in techniques including SIMS and MALDI [1-3]. Critical to the success of these developments is an understanding and optimisation of the interaction between laser photons and desorbed neutrals. Here we report on the post-ionisation of the pharmaceutical verapamil using 50 fs laser pulses of UV and IR photons. Sputtering was performed with atomic, cluster and polyatomic primary ions (Au, Au3 and C60). Measured post-ionisation useful yields of some high mass diagnostic ions were increased by up to one order of magnitude compared with SIMS, with scope for a further order of magnitude by reducing the primary ion pulse length. We observe also the dependence of post-ionisation yield with respect to laser fluence, which appears to depend on the energetics of the sputtered neutrals.
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