Low‐temperature SIMS mass spectra of diethyl ether

Abstract

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.

‘Bubble chamber model’ of fast atom bombardment induced processes

“…Our experimental observations are in agreement with theoretical estimates of R evap for different compounds. For example, highly volatile diethyl ether survives in the liquid state for only several minutes after melting,22 while an ethanol sample lasts for hours slightly above its melting temperature 11…”

“…The results of our recent studies of various types of compounds in a wide temperature range of about 200°C, using ambient and low‐temperature (LT) FAB‐SIMS,6–23 have revealed a number of facts which can substantiate Vestal's model. First, the existence of not only a quantitative but a qualitative difference between characteristics of sputtering from the same substance in the solid and liquid states was demonstrated experimentally 10,13,14,17–23. Then, a simple estimate has shown that all liquids ever studied under FAB conditions were in a superheated state under the mass spectrometric vacuum.…”

“…To develop the present model, the results of our earlier LT‐FAB/SIMS studies6–23 were used. These experiments were performed using two types of mass spectrometer: a magnetic sector mass spectrometer MI‐1201E (SELMI Works, Sumy, Ukraine) and a VG‐ZAB‐SEQ (Micromass, UK).…”

“…The following previously published LT‐FAB‐SIMS data are invoked in the present discussion: LT‐FAB11 and LT‐SIMS12,13 data for pure alcohols (methanol and ethanol) including temperature dependences;13,18,23 data on fractionation of alcohol mixtures;21,23 LT‐FAB data on glycerol and glycerol/water mixtures,6 water and glycerol solutions of simple organic molecules,7,9,14–16 water ice;6,8,14 and LT‐SIMS data for diethyl ether22 and some other organic solvents 23…”

Kinetic Energy Release of Protonated Methanol Clusters Using the Low-Temperature Fast-Atom Bombardment: Experiment and Theory Combined

“…10,11 Cluster ion formation from selected cooled matrices, especially from alcohols and water, became the focus of low-temperature mass spectrometric measure-ments. [12][13][14][15][16] Important features of phase transitions in the lowtemperature range were mapped out, yielding information relating to cryochemistry and cryobiophysics. 12,13 Methanol clusters have been studied by a variety of techniques, with a view to probing structure, binding energy and dissociation dynamics and proton transfer.…”