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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Experimental Evaluation and Optimization of Structures for Lossless Ion Manipulations for Ion Mobility Spectrometry with Time-of-Flight Mass Spectrometry

We report on the performance of Structures for Lossless Ion Manipulation (SLIM) devices as a means for transmitting ions and performing ion mobility separations (IMS). Ions were successfully transferred from an electrospray ionization (ESI) source to the TOF MS analyzer by means of a linear SLIM device and an alternative arrangement including a 90° turn. First, the linear geometry was optimized for radial confinement by tuning RF on the central ‘rung’ electrodes and potentials on the DC-only guard electrodes. Selecting an appropriate DC guard bias (2-6 V) and RF amplitude (≥160 Vp-p at 750 kHz) resulted in the greatest ion intensities. Close to ideal IMS resolving power was maintained over a range of applied voltages. Second, the 90° turn was optimized for radial confinement by tuning the RF on the rung electrodes and DC on the guard electrodes; however, both resolving power and ion transmission showed a dependence on these voltages and the best conditions for both were > 300 Vp-p RF (685 kHz) and 7-11 V guard DC bias. Both geometries provide IMS resolving powers at the theoretical limit (R~58), showing that the negative “racetrack” effect from turning around a corner can be successfully avoided, as well as the capability for essentially lossless ion transmission.

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