title: Soft-sputtering of insulin films in argon-cluster secondary ion mass spectrometry.
abstract: In secondary ion mass spectrometry (SIMS) of organic substances, the dissociation of the sample molecules is crucial. We have developed SIMS equipment capable of bombardment, where the primary ions are argon cluster ions with kinetic energy per atom controllable down to 1  eV. We previously reported the detection of intact ions of insulin and cytochrome C using this equipment. In this paper, we present a detailed characterization of the emission of secondary ions from insulin, focusing on the difference in secondary ion yield between intact ions and fragment ions by varying the incident angle of the cluster ions. The emission intensity of the intact ions was changed drastically due to the exposed dosage and incident angle of the cluster ions in contrast to the fragment ions. We discuss these results based on the manner in which the argon-cluster ions collide with the organic solid.
authors: Department of Mechanical and System Engineering, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo, 671-2280, Japan.
authors: Shohei
authors: S
authors: Oshima
authors: Ippei
authors: I
authors: Kashihara
authors: Kousuke
authors: K
authors: Moritani
authors: Norio
authors: N
authors: Inui
authors: Kozo
authors: K
authors: Mochiji
mesh_terms: D001128:Argon / Q000737:chemistry*; D006801:Humans; D007328:Insulin / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods*
chemical_list: D007328:Insulin; D007477:Ions; D001128:Argon