By using a high-resolution electron energy monochromator low-energy electron attachment to gas-phase glycine (H2NCH2COOH, or G) has been studied by means of mass spectrometric detection of the product anions. In the same way as for several other biologically relevant molecules no stable parent anion was formed by free electron attachment. The largest dissociative electron attachment (DEA) cross-section, approximately 5x10(-20) m2, was observed for (G-H)-+H at an electron energy of 1.25 eV. Glycine and formic acid (HCOOH) have several common features, because a precursor ion can be characterized by electron attachment to the unoccupied pi* orbital of the -COOH group. At higher incident electron energies several smaller fragment anions are formed. Except for H-, which could not be observed in this study, there was good agreement with an earlier investigation by Gohlke et al.

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A new experimental approach based on swarm techniques was proposed for the measurement of rate constant of an electron attachment process at atmospheric pressure by means of negative ion mobility spectrometry. In this technique, sample is continuously delivered to the drift gas, which then enters into the drift region where it reacts with a counterflowing swarm of electrons injected by the shutter grid. As a result, negative ions are formed in the drift tube and a tail appears in the ion mobility spectrum. It is shown that the tail fits to an exponential function and the magnitude of the electron attachment rate constant value can be extracted from the plot of ln(ion intensity) versus the drift time. Unlike conventional electron swarm technique, it is not necessary, in this method, to perform the experiment at various concentrations of the sample. The approach proposed was typically examined for CCl 4 , CHCl 3 , and CH 2 Cl 2 and the rate constants were estimated for a range of mean electron energies (〈 〉 ) 0.28-0.88 eV) in nitrogen buffer gas at 300 K. Good agreement between the rate constant measured in the present work with those reported in earlier works is observed.

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