Fission-fragment-induced desorption

The field-desorption spectra of several aldoses and ketoses ionized by attachment of potassium ions led to the identification of the characteristic fragments formed by loss of small molecules, and related secondary ion analysis was carried out on various purine and pyrimidine nucleosides. Also in the nucleoside field a set of mathematical procedures has been applied to the spectra derived from 125 compounds and has led to pattern recognition and interpretation. Underivatized nucleosides have been studied by a method based on pulsed laser and fission fragment-induced desorption, and also by a chemical ionization technique dependent on a direct exposure probe. ... 

The technique introduced by the Macfarlane group was originally referred to as Coulomb ionization since the process of excitation was similar to the Coulomb excitation of nuclei by fast heavy ions. The term fission-fragment induced desorption (FFID) was used by Field and ChaiC to describe the technique without implying a particular mechanism. Other investigators, including Bo Sundqvist at the Tandem... 

This method was developed by MacFarlane [93], who, in order to induce desorption, used high kinetic energy fragments ( Tc, 100 MeV) produced by nuclear fission of californium. Different ionization modes may occur electron transfer (M and M ) [94], proton transfer ([M + H] and [M-H] ) and, finally, cationization ([M + Na] ). Figure 13 shows the comparison of spectra obtained under PDMS-conditioned laser desorption. 

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