| Development and characterization of energy-focusing constant-momentum acceleration (CMA) for velocity-based mass separations is the focus of this work. Specifically, CMA has been examined with two novel approaches based on time-of-flight mass spectrometry (TOFMS): zoom-TOFMS and distance-of-flight mass spectrometry (DOFMS). These techniques are made possible because CMA energetically focuses ions at a single moment, known as the energy-focus time (tef), which serves as the detection time for both techniques. In contrast, all commercial TOFMS systems employ constant-energy acceleration (CEA) that provide a spatial ion focus. Therefore, zoom-TOFMS and DOFMS provide a complementary mode of ion focus to existing instrumentation, but with distinct advantages in each case.;In essence, zoom-TOFMS is a combination approach that enables both conventional, CEA- and CMA-TOFMS to be employed on the same instrument platform as switchable operational modes. The zoom part of zoom-TOFMS comes from ion detection at tef with CMA-TOFMS mode. Specifically, for the narrow mass range that is detected near tef, mass resolution, duty factor, and sensitivity are improved over CEA-TOFMS---much like when a camera's zoom lens is used. The viability of zoom-TOFMS has been evaluated on two separate instrument platforms; namely, with a 43-cm direct-current glow-discharge instrument and with a 35-cm inductively coupled plasma (ICP) system.;Distance-of-flight MS is an emerging velocity-based mass-separation technique that combines advantages of TOFMS and spatially dispersive, simultaneous multichannel MS instruments. Conceptually, DOFMS is quite similar to CMA-TOFMS. However, in DOFMS, ions are measured at their m/z-dependent distances at tef by simultaneously directing the ions onto a spatially selective detector. Results from coupling DOFMS to a laser ablation ICP system will be presented along with the first implementation of DOFMS with a commercially available IonCCD camera detection system. Design, construction, and performance of these instruments are described and a view toward future work is offered. |
