Fast atom bombardment of organic substrates at controlled low temperatures

Low-temperature SIMS mass spectra of diethyl ether

For the first time a secondary ion mass spectrum of diethyl ether was obtained at low temperature. The spectrum recording became possible by carefully selecting the range of experimental conditions for the production of a cluster-type spectrum. This range is specified by the threshold for spectrum appearance above the melting temperature of the frozen sample and a fairly short time span of existence of the liquid estimated as only a few minutes. The latter necessitates rather rapid spectrum detection. In practice, about 1 min was available for recording of the cluster-type spectra. The secondary emission mass spectrum of diethyl ether appeared to be rich in peaks: along with abundant protonated clusters M(n).H(+) (n = 1-12), unusually intense [M(n) - H](+) and weaker M(n) (+.) peaks were present accompanied by several sets of fragmented clusters, [M(n) - 15](+), [M(n) - 29](+), [M(n) - 27](+), [M(n) - 45](+), and monohydrates, M(n).H(2)O.H(+). The analysis of all the peaks showed that the pattern of fragment clusters is qualitatively similar to the pattern of fragmentation of the diethyl ether molecular ion under high-energy electron impact. The general features of the behaviour of diethyl ether under low-temperature mass spectrometric conditions were similar to those observed earlier for some other organic solvents.