Sample temperature dependence of plasma desorption mass spectra of biomolecules

The effect of sample/substrate temperature on the [sup 252]Cf plasma desorption (PD) ion yield of three different peptides with molecular weights between 231 and 5,733 has been studied in the temperature range from [minus]100 to +100[degrees]C. The variation in the positive ion yield of the peptide molecular ions and lower mass fragment ions has been investigated as a function of the sample/substrate temperature. A decrease in the molecular ion yield has been observed at temperatures both higher and lower than ambient, whereas lower mass fragment ions show an increase in their yield at higher temperatures. Possible explanations of the above observations are discussed. 16 refs., 6 figs.