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High-resolution secondary ion mass spectrometry (SIMS) for use in chemistry

1981; Elsevier BV; Volume: 39; Issue: 1 Linguagem: Inglês

10.1016/0020-7381(81)80123-4

1873-3034

Klaus-Dieter Klöppel, Günther von Bünau,

Mass Spectrometry Techniques and Applications

A secondary ion (SI) source was adapted to a Varian 311A (double-focusing) mass spectrometer in order to extend its applicability to existing problems in organic mass spectrometry and to material testing. Spectra were obtained from Au targets showing clusters up Au5. Phenylalanine on silver gave SI spectra from samples of ∼10−10 g. SI spectra from other amino acids, spread as their hydrochlorides on titanium, were also recorded and used to distinguish between 48Tix16Oy+ and 48Tix-116Oy+3+ ions by peak matching. A resolution of at least 8000 was established. Comparison of the SI spectrum of proline (hydrochloride) with proline mass spectra from electron impact (EI), chemical ionization (CI) with methane, and field desorption (FD) revealed that secondary ionization leads to less fragmentation than EI and more fragmentation than CI. Nearly fragment-free SI spectra were obtained from Malachite Green and quinine using 2-keV primary Ar+ ion currents of 10−7 A cm−2.