Thomas A. Lehman

Isotope effects in collision-activated dissociations of simple ions

Abstract Collision-activated dissociations of diatomic and triatomic ions show isotope effects that depend on a simple function of the masses but not on instrumental parameters such as accelerating voltage or detector slit width. Results for diatomic and triatomic species are in excellent agreement with a collisional interaction theory.

Dehydration of the protonated butane-2,3-dione–ethanol ion [(CH3CO·-CO·CH3)(C2H5OH)H+] in the gaseous phase

Among the ions present in the ion cyclotron resonance spectrum of a mixture of butane-2,3-dione and ethanol at low ionizing voltage is a species of m/e 115 which is shown by deuterium labelling to correspond to a product of dehydration of the mixed-solvate (CH3COCOCH3)(C2H5OH)H+ in which both hydrogen atoms lost originate from the hydroxy-group of ethanol.

Direct observation of the H2NO2– ion

The structure of the gaseous H2NO2– ion in the negative chemical ionisation mass spectrum of butyl nitrate is suggested by charge-reversal chemical-activation mass spectrometry and confirmed by calculation at the 4–31 G level.