Fragment ion formation from n‐alkanes and cycloalkanes by plasma desorption

The plasma desorption of hydrogen loss fragment ions from frozen films of several classes of aliphatic volatile hydrocarbons was investigated with 252 Cf plasma desorption mass spectrometry. A time‐of‐flight instrument suitable for the reproducible sampling and analysis of volatile hydrocarbons in the solid state was designed for this study. Representative compounds from the n ‐alkanes and cycloalkanes were analyzed. For all the compounds studied, radical molecular ions. M +. , and hydrogen loss fragment ions, [M  m H] + with m varying from 1 to 10, were produced. The length of the alkane chain, the size of the alkane rings and the stability of the resulting H‐loss ions affected the number and abundance of these ions. Smaller molecules underwent proportionally more hydrogen loss than larger molecules of the same class.