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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The Use of Capacitive Transimpedance Amplifier Array Detectors for Mass Spectrometry

Zarzana, Christopher Andrew January 2011 (has links)
Mass spectrometry is a powerful tool in the field of analytical chemistry. Though there have been numerous advances in mass analyzer technology over the decades, there has been comparatively little advancement in mass spectrometer detector technology. The development of the scientific charged-coupled device over 30 years ago brought the advantages of simultaneous detection over single channel detection to optical spectroscopy, including higher signal-to-noise ratios for a fixed analysis time, shorter analysis time to obtain a given signal-to-noise ratio, and greater sample throughput. While the use of array detectors to achieve simultaneous detection is commonplace in optical spectroscopy, ion detectors for mass spectrometry have lagged behind.Over the last decade, a new type of ion detector, the capacitive transimpedance amplifier (CTIA) array detector, has been developed that has a number of properties that make it an excellent tool for simultaneous detection using dispersive mass spectrometers. The CTIA array detector has high sensitivity as well as high gain stability, allowing it to excel in applications that require high precision measurements of ion signals, such as isotope ratio mass spectrometry.Capacitive transimpedance amplifier array detectors have previously been used to demonstrate the power of simultaneous detection on Mattauch-Herzog double focusing mass spectrometers, but the non-linear mass dispersion of these instruments means that the resolution is not constant across the array. A different type of dispersive instrument, the linear cycloid, has a linear mass dispersion, making it a good candidate for an array detector.The first detailed characterization of gain, read noise and dark-current noise, as well as of operating behavior over a range of temperatures, of the DM0025, a 1696 pixel CTIA array detector was performed.In addition, the first-ever combination of a CTIA array detector with a linear cycloid mass spectrometer was developed. This combined instrument demonstrated simultaneous detection of multiple masses, as well as a linear mass range. The results from the detailed characterization of the detector were used in conjunction with measurements of the performance of the combined instrument to suggest improvements for the next generation of linear cycloid instruments with CTIA array detectors.
2

A Solid-State Ion Detector for Use in Portable Mass Spectrometry

Sabbah, Sadek Salman 01 November 2014 (has links)
Mass spectrometry has long been used as a scientific tool in a wide variety of applications. A portable mass spectrometer would make many of these applications faster and more efficient. One of the key components of a mass spectrometer is its ion detection system; to make a mass spectrometer portable, this system must be small and involve as few components as possible. Single ion detection has been achieved through several methods, nearly all of which are well-known and understood. These methods, however, often require bulky vacuum and/or cooling systems in order to achieve high sensitivity. An ion detection system that can achieve high sensitivity under atmospheric pressure and normal temperature conditions would make portable mass spectrometry much more feasible. This thesis introduces a new method of detecting ions which does not require a vacuum or cold temperatures to operate: the solid-state ion detector, or SSID. Although ion detection using solid-state devices has been investigated previously, this work introduces metal-oxide-semiconductor field-effect transistors (MOSFETs) in a cascode configuration which acts as the primary detector when combined with a Faraday cup and mechanical switch. This detector is followed by a second amplifying stage which features RC-filters to help reduce noise and improve the detector's overall sensitivity. The detector is placed on a printed circuit board that was designed to fit a pre-determined system. Additional power circuitry for the mechanical switch was also designed and added to the detector circuitry. The SSID will be most sensitive when the input capacitance is made as small as possible. With this in mind, MOSFETs with a very low (< 1pF) gate capacitance were fabricated at BYU for use in the SSID. The performance of these MOSFETs was compared to a commercially available device in the same configuration. When tested, both MOSFETs had a sensitivity of hundreds of electrons when integrated in the complete SSID circuit. The commercial MOSFET demonstrated an estimated sensitivity of 150 electrons. The SSID shows much promise, and suggestions are made for further improving it to achieve even higher sensitivity levels. If made more sensitive, the next step would be to create an array of SSID detectors to be used in a portable mass spectrometer.
3

System Design For Non-Destructive Detection Of Ions In A Paul Trap Mass Spectrometer

Gorde, Dnyaneshwar R 04 1900 (has links) (PDF)
No description available.

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