A miniature quadrupo]e mass-spectrometer array consisting of 16 rods in a 4 X 4 array is reported. Each rod is 25 mm long and 2 mm diameter. The ionizer is of a miniature Nier-type design, and the detector is a channel type electron multiplier. Operating frequencies are 5.3 Mtlz, 7.1 MH7, and 12.9 MHz. The mass range demonstrated herein is 1-300 amu; and the resolution of the system is 0.1-0.5 arnu (FWHM), or m/Am == 600, The present sensitivity is calculated and measured to be approximately 1 x 10'2 counts/torr-sec.
A Paul ion trap has been developed for use as a high-resolution mass spectrometer. It is of small size (r 0 ϭ10 mm), having a resolution of m/⌬mϭ324, which is limited by the machining accuracy of the trap. It has a demonstrated mass range of 1-300 u, and a sensitivity of 2ϫ10 14 counts/Torr s, or to 500 parts per trillion detection sensitivity in a typical vacuum of 10 Ϫ5 Torr. Ionization of the room-temperature gas within the trap is carried out with an electron beam traversing the trapping volume. The trap operates in a radio frequency only mode, and no dc is required. Trapping is accomplished within the well depth of the dynamic radio frequency potential, and no cooling gas is required, such as helium. This combination of factors makes the trap potentially of use for autonomous operation in harsh environments requiring low power, low weight, and low volume, such as undersea, on the surface of a planet or asteroid, or in a spacecraft.
A new approach to quadrupole mass spectrometric measurement and analysis has been used to study the electron impact ionization of SO2 to determine the cross sections for the production of O+, S+, SO+, and SO+2 from SO2. The relative flow technique is utilized to determine the cross section values. The threshold potentials are found to be 12.5 eV (SO+2), 16.5 eV (SO+), 16.5 eV (S+), and 23.5 eV (O+). The partial cross section values at 100 eV electron impact energy are 4.20×10−16 cm2 for SO+2, 1.65×10−16 cm2 for SO+, 0.90×10−16 cm2 for S+, and 0.25×10−16 cm2 for O+.
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