Characterization of a Focal Plane Camera Fitted to a Mattauch−Herzog Geometry Mass Spectrograph. 1. Use with a Glow-Discharge Source

Abstract

A Mattauch-Herzog geometry mass spectrograph (MHMS) has been equipped with a novel array detector, the focal plane camera (FPC). The FPC consists of an array of gold Faraday cups, each coupled to its own integrator, with interrogation of the integrators performed by a multiplexer. The initial coupling of this instrument with a pin-type glow discharge source has provided limits of detection in the single to hundreds of nanograms per gram regime; isotope ratio accuracy and precision better than 5% error and 0.2% RSD, respectively; and a linear dynamic range of at least 6 orders of magnitude. A current weakness of the FPC is its pixel size, which limits both sensitivity and baseline resolution (to R = 130). The minimum data acquisition time for multiple images at present is 1 ms/image, with a dead time of 3.2 ms between images, which will limit the ability of the FPC to monitor extremely short transient signals.

Use of a novel array detector for the direct analysis of solid samples by laser ablation inductively coupled plasma sector-field mass spectrometry

“…This instrument has been coupled to several ionization sources, including both dc and pulsed glow discharges (GD) [21,28], a microwave plasma torch (MPT) [29], and an ICP [27]. Since the ICP-MHMS has been described previously, only the operating parameters pertinent to the present experiment will be detailed.…”

“…The accumulated ion signal on each collector is integrated with its own capacitive trans-impedance amplifier; the array of amplifiers is read with a low-noise multiplexer. Further details on the FPC and its coupling to the MHMS can be found elsewhere [21]. The operating conditions of the LA-ICP-MHMS-FPC instrument are summarized in Table 1.…”

“…This discrepancy can be attributed to the mass analyzer, not the FPC detector. Recent studies have shown that comparable limits of detection are obtained with the MHMS using either SEM or FPC detection with both GD and ICP ionization [21,32]. Moreover, due to the compact nature of the MHMS, a low acceleration potential is utilized (1 kV), resulting in a significant loss in transmission efficiency and sensitivity.…”

“…Additionally, since these arrays can be fabricated with micrometer scale detector elements, both the number of detectors and detector density is greatly increased over what is feasible with MC-SFMS instruments utilizing discrete single-channel detectors, resulting in greater mass coverage. One such array detector, termed the focal plane camera (FPC), has recently been developed and fitted to a Mattauch-Herzog geometry mass spectrograph (MHMS) [21]. A key feature of the MHMS is the presence of a flat focal plane along which all m/z values are focused simultaneously, allowing the use of a planar array detector.…”

Peer Reviewed: Plasma Source TOFMS

“…Alternatively, a double-focusing mass spectrograph can be fitted with a focal-plane camera, thereby creating the MS-equivalent of CCD cameras. These devices can monitor the entire mass range of interest continuously and simultaneously (4). TOFMS has also been explored as a method for overcoming some of the limitations of PSMS and is gaining popularity for multielemental and multiisotopic analysis of fast transient signals (5)(6)(7)(8).…”