The interaction between the matrix and analyte molecules are studied with a high resolution MALDI imaging technique in an orthogonal-injection TOF mass spectrometer. The analyte incorporation and distribution patterns have been clearly demonstrated. Purified protein analytes were found to be homogeneously incorporated in large single crystals of DHB and sinapinic acid matrices, with no evidence for preferred crystal faces. Segregation of some species was observed and appeared to correlate with analyte hydrophobicity, and to a lesser extent analyte mass or mobility. The influence of incident laser parameters on sensitivity in MALDI has been investigated using orthogonal-injection time-of-flight (TOF) instruments. A qualitative comparison was first made between the beam profiles obtained with a N2 laser and a Nd:YAG laser using 2-m long optical fibers. The N2 laser gives better sensitivity, consistent with a more uniform fluence distribution and therefore better coverage of the N2 laser profile. Most of the difference disappears when a 30-m long fiber is used or when the fibers are twisted during irradiation to smooth out the fluence distribution. In more systematic measurements, the total integrated ion yield from a single spot (a measure of sensitivity) was found to increase rapidly with fluence to a maximum, and then saturate or decrease slightly. For a fluence near threshold, the integrated yield has a steep (cubic) dependence on the spot size, but the yield saturates at higher fluence for smaller spots. The area dependence is much weaker (close to linear) for fluence values above saturation, with the result that the highest integrated yields per unit area are obtained with the smallest spot sizes. Finally the detection properties of the MCP detector were studied with a hybrid MCP and CuBe venetian blind converter detector. The measurements show that the detection efficiency of the MCP drops with the increasing of ion mass and the decreasing of the ion energy. The secondary electron emission coefficient of the MCP shows a linear dependence on mass and a power law dependence on velocity (~ 3.2). No clear velocity threshold is observed for secondary electron emission. / May 2009

The interaction between the matrix and analyte molecules are studied with a high resolution MALDI imaging technique in an orthogonal-injection TOF mass spectrometer. The analyte incorporation and distribution patterns have been clearly demonstrated. Purified protein analytes were found to be homogeneously incorporated in large single crystals of DHB and sinapinic acid matrices, with no evidence for preferred crystal faces. Segregation of some species was observed and appeared to correlate with analyte hydrophobicity, and to a lesser extent analyte mass or mobility. The influence of incident laser parameters on sensitivity in MALDI has been investigated using orthogonal-injection time-of-flight (TOF) instruments. A qualitative comparison was first made between the beam profiles obtained with a N2 laser and a Nd:YAG laser using 2-m long optical fibers. The N2 laser gives better sensitivity, consistent with a more uniform fluence distribution and therefore better coverage of the N2 laser profile. Most of the difference disappears when a 30-m long fiber is used or when the fibers are twisted during irradiation to smooth out the fluence distribution. In more systematic measurements, the total integrated ion yield from a single spot (a measure of sensitivity) was found to increase rapidly with fluence to a maximum, and then saturate or decrease slightly. For a fluence near threshold, the integrated yield has a steep (cubic) dependence on the spot size, but the yield saturates at higher fluence for smaller spots. The area dependence is much weaker (close to linear) for fluence values above saturation, with the result that the highest integrated yields per unit area are obtained with the smallest spot sizes. Finally the detection properties of the MCP detector were studied with a hybrid MCP and CuBe venetian blind converter detector. The measurements show that the detection efficiency of the MCP drops with the increasing of ion mass and the decreasing of the ion energy. The secondary electron emission coefficient of the MCP shows a linear dependence on mass and a power law dependence on velocity (~ 3.2). No clear velocity threshold is observed for secondary electron emission.

The interaction between the matrix and analyte molecules are studied with a high resolution MALDI imaging technique in an orthogonal-injection TOF mass spectrometer. The analyte incorporation and distribution patterns have been clearly demonstrated. Purified protein analytes were found to be homogeneously incorporated in large single crystals of DHB and sinapinic acid matrices, with no evidence for preferred crystal faces. Segregation of some species was observed and appeared to correlate with analyte hydrophobicity, and to a lesser extent analyte mass or mobility. The influence of incident laser parameters on sensitivity in MALDI has been investigated using orthogonal-injection time-of-flight (TOF) instruments. A qualitative comparison was first made between the beam profiles obtained with a N2 laser and a Nd:YAG laser using 2-m long optical fibers. The N2 laser gives better sensitivity, consistent with a more uniform fluence distribution and therefore better coverage of the N2 laser profile. Most of the difference disappears when a 30-m long fiber is used or when the fibers are twisted during irradiation to smooth out the fluence distribution. In more systematic measurements, the total integrated ion yield from a single spot (a measure of sensitivity) was found to increase rapidly with fluence to a maximum, and then saturate or decrease slightly. For a fluence near threshold, the integrated yield has a steep (cubic) dependence on the spot size, but the yield saturates at higher fluence for smaller spots. The area dependence is much weaker (close to linear) for fluence values above saturation, with the result that the highest integrated yields per unit area are obtained with the smallest spot sizes. Finally the detection properties of the MCP detector were studied with a hybrid MCP and CuBe venetian blind converter detector. The measurements show that the detection efficiency of the MCP drops with the increasing of ion mass and the decreasing of the ion energy. The secondary electron emission coefficient of the MCP shows a linear dependence on mass and a power law dependence on velocity (~ 3.2). No clear velocity threshold is observed for secondary electron emission.

N/A / Thesis / Master of Science (MS)

A description of a Dempster type double focusing mass spectrograph, converted to a mass spectrometer is reported. The latter part of the thesis deals with an investigation of a Shaw type solid ion source. Ten microgram samples of VaCl2 and SrCl2 yielded measurable ion currents of 1.0 x 10-11 amperes. Results with UF4 and PbI2 are also reported. / Thesis / Master of Science (MS)

No description available.

The relative abundances of the stable and long-lived Isotopes of rubidium, cesium, strontium, cerium, neodymium, and samarium resulting from the ther­mal neutron fission of U^235 and Pu^239 were determined mass spectrometrically. Special precautions were taken to eliminate or at least minimize contamination of the sub-microgram quantities of fission products with the naturally occurring elements. By using isotope dilution the yields of isotopes of different elements were related with very good precision. Sufficient information was available to evaluate from such results the absolute cumulative yields of twenty-seven mass chains for U^235 fission. It was possible from the results of the present study of make a quantitative comparison between the yields of the heavy fragments for U^235 and Pu^239 fission, with special attention being given to the fine structure supposedly resulting from the influence of nuclear shells involving 50 and 82 neutrons. / Thesis / Master of Science (MS)

An electron multiplier has been developed which has increased the sensitivity of an existing mass spectrometer toy a factor of 10^5. This increased sensitivity has permitted determination of fission yields of substances that have undergone little fission. Two such samples, for which the rare gas isotopes have been analysed, are Bohemian pitchblende and the products resulting from the neutron fission of Th232, The Bohemian ore exhibited more neutron fission than any uranium deposit previously analysed. An explanation of this effect may be obtained by considera­tion of the geological and chemical nature of the deposit. The neutron fission of thorium, which shows fine structure in both the xenon and krypton regions, is similar to the patterns of u235 U235 and pu239, / Thesis / Master of Science (MS)

<p> A description of the McMaster tandem mass spectrometer is given and the usefulness of this instrument in high sensitivity applications is discussed.</p> <p> The pulse characteristics of the 17 stage Allen type electron multiplier which is used on the two stage mass spectrometer were determined and possible means of achieving an improved response in counting applications are discussed.</p> <p> An ion source of the crucible variety was constructed which made possible the detection of 10^-9 grams of a tin isotope. This source was used to detect sub microgram quantities of an enriched tin sample and was also used for the qualitative analysis of a sample which contained tin extracted from a reactor irradiated fuel rod.</p> / Thesis / Master of Science (MSc)

The uploaded file contains both Part 1 and Part 2 of the work. / An abstract is not provided. / Thesis / Master of Science (MSc)