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Signal shapes observed in photon-induced field ionization mass spectra

Item Type:Article
Title:Signal shapes observed in photon-induced field ionization mass spectra
Creators Name:Block, J.H. and Jentsch, T.J. and Drachsel, W.
Abstract:Field desorption initiated by photon pulses of duration 2.5 ns (or 5.0 ns) is studied by time-of-flight mass spectrometry. The sudden temperature rise caused by photon impact perturbs steady-state adsorption. Thermal desorption, field-directed particle-hopping and surface diffusion change the particle concentration in the monitored ionization zone at the emitter apex. Delayed supply processes lead to signal broadening (tailing). From the signal shapes, delay times from a few nanoseconds up to several milliseconds have been derived. By measuring time-dependent total ion currents, without mass-analysis, delay times of up to some seconds have been observed. The influence of field strength, laser power density and laser pulse repetition-rate is investigated for different supply regimes. A diffusion model is presented which can qualitatively explain the observed phenomena. Experiments are performed with Cu and Ir emitters at 80 K and with argon, ethylene and xenon as test gases.
Source:International Journal of Mass Spectrometry and Ion Physics
Page Range:195-213
Date:May 1981
Official Publication:https://doi.org/10.1016/0020-7381(81)80067-8

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