Harry T. Jonkman

Secondary ion mass spectrometry of small-molecule solids at cryogenic temperatures. V [1]. Oxygen

Abstract Positive secondary ion mass spectra of neat solid O2 and O2 diluted with argon at 15–20K were measured as a function of the nature and energy of the primary ions (He+, Ar+, Kr+, 0.5–4.0 keV). With He+, the spectrum of solid O2 is dominated by O2 and O+ peaks, with Ar+ and Kr+, it is dominated by an intense cluster series O+3n+2, n = 0,1,2….

Secondary Ion Mass Spectrometry of Small-Molecule Solids at Cryogenic Temperatures. IV. Carbon Dioxide, Carbonyl Sulfide and Carbon Disulfide

Secondary ion mass spectra of neat solid CO2, COS and CS2 and of CO2 diluted in solid argon were measured as a function of the nature and energy of the primary ions (He+, Ne+, Ar+, Kr+, Xe+, 1.0-4.5 keV). All of the solids produced a rich variety of positive and negative secondary ions. Many of these have masses considerably in excess of the molecular weight of the parent molecules, particularly with primary ions of large momentum. Carbon dioxide produces well-defined cluster series with CO2 as the solvating unit. Carbonyl sulfide and carbon disulfide yield a complex pattern of positive and negative cluster ions.

Secondary Ion Mass Spectrometry of Small Molecules Held at Cryogenic Temperatures

In recent years more emphasis has been placed on the analytical potential of Secondary Ion Mass Spectrometry (SIMS) for the study of organic materials [1,2,3]. We wish to report on static SIMS experiments on a few simple molecules condensed on a copper substrate held at low temperatures. For the experiments we used an Extranuclear Inc., quadrupole massfilter equipped with a Bessel box type energy filter. The bandwidth of the ions accepted in the massfilter was set at 1 eV. Our ion gun is differential pumped and during the experiments a pressure in the 10−9 torr range could easily be maintained in the main chamber. Our primary ion beam current density was between 1 and 10 nA/cm2 and the beam energy was varied between 500 and 5000 eV. As primary ion we used He+,Ne+, Ar+, Kr+, and Xe+. The nature of our samples made it necessary to use an electron floodgun to compensate for charge buildup on the sample. The energy of the flooding electrons was kept below 7 eV. In all the experiments the temperature of the sample was held at 15°K. In Fig.1 the positive SIMS spectrum of neat methane using a 1 keV Ne+ beam shows fragments up to C11.