Ml. Easterling et al., RF CAPACITIVE COUPLING WITH EFFICIENT GATED TRAPPING IN INTERNAL MATRIX-ASSISTED LASER-DESORPTION IONIZATION FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE, Journal of the American Society for Mass Spectrometry, 8(2), 1997, pp. 195-198
A method to combine gated trapping and capacitive coupling into a sing
le experiment is reported. This is achieved with a circuit that allows
isolation of the electronic network that gates the trapping voltage f
rom the circuit that enables capacitive coupling of the rf excitation
signal to the trapping plates. When the capacitive coupling network is
not isolated from the gated trapping network, the trapping voltage ch
anges occur on a 100 mu s or longer timescale, which is incompatible w
ith efficient capture of ions formed by matrix-assisted laser desorpti
on ionization. Isolation of the two networks allows the trapping volta
ge to be gated with less than a 10 mu s risetime. The effectiveness of
this approach is demonstrated by a set of experiments carried out wit
h and without the benefit of the isolation of capacitive coupling from
gated trapping. (C) 1997 American Society for Mass Spectrometry