AVS 57th International Symposium & Exhibition
    Applied Surface Science Wednesday Sessions
       Session AS-WeA

Paper AS-WeA12
IonCCDTM for Charged Particle Detection: From sub-keV Electrons and keV Atomic and Molecular Ions to Hyperthermal Biomolecular Ions

Wednesday, October 20, 2010, 5:40 pm, Room Cochiti

Session: Surface Mass Spectrometry: SIMS and Beyond
Presenter: O. Hadjar, OI Analytical
Authors: O. Hadjar, OI Analytical
W.C. Schnute, Dionex Corporation
J. Laskin, Pacific Northwest National Laboratory
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We will present the latest data using a pixel array for charged-particle detection based on a modified charge-coupled device technology (IonCCDTM). The array is 51 mm long, consists of 2126 pixels (1.5 mm long) with 0.024 mm pitch. The charged particle beam is collected individually by each pixel, and hence, the IonCCD signal response is proportional to the beam flux and the collection time (integration time). With an integration time of 82 µs and a readout time of 2.7 ms, the IonCCD produces 360 frames a second. We will present data showing the direct use of the IonCCD as a beam profiler (one dimensional) to characterize the positively and negatively charged ion beams exiting an RF‑only collisional quadrupole. The latter is used to thermalize and collimate the ions produced by an atmospheric pressure electrospray source. When mounted on the focal plane of a miniature Mattauch-Herzog geometry sector-field analyzer, the IonCCD produces a mass‑over‑charge (m/z) spectrum of the produced ions. For high sensitivity measurements we coupled the IonCCD to a micro-channel plate (MCP). In this manner, the IonCCD is used as an anode to read the electrons produced by the MCP. We will present MCP-IonCCD mass spectra using an electron-impact (EI) source to produce singly and doubly charged Xe ions. We compare the performance of the MCP-IonCCD hybrid detector to that of the IonCCD itself. We will apply this technology to the simultaneous m/z separation and detection of negative ions produced by electrospray ionization that generates beams of deprotonated molecules that are typically 10 times weaker than ion beams produced in the positive mode.