ION IMAGE DETECTION WITH A MICROCHANNEL PLATE EVALUATED BY USING A CHARGE COUPLED DEVICE CAMERA

The performance of the Ion Image detection system in Ion microscopy is characterized in detail. Using a charge coupled device (CCD) slow scan camera, It is possible to isolate the behavior of the microchannel plate/fluorescent screen (MCP/FS) used to detect the Incoming Ions. The highly quantitative and reproducible behavior of the CCD system allows for the analysis of MCP/FS linearity, mass dependence, homogeneity, and noise characteristics. The response of the MCP/FS is highly linear at all applied voltages. The mass dependence is complex but can be interpreted in the context of Ion-Induced electron emission from a solid surface and the nature of the MCP sensitive surface. On extended use the MCP suffers from a loss of sensitivity near Its center, which is slightly corrected by the nature of the camera optics. The background noise can be separated into Instrumental noise form the postmagnet ion pump of the ion microscope and background events inherent to the MCP. The signal-noise relationship is studied by using the various means of increasing signal and gives rise to ideal detection parameters. The overall performance of the MCP/FS is assessed and the significance of the observed behavior to MCP based ion detectors is discussed. © 1990, American Chemical Society. All rights reserved.