A constant-momentum/energy-selector time-of-flight mass spectrometer

Abstract

A matrix assisted laser desorption/ionization time-of-flight mass spectrometer has been built with an ion source that can be operated in either constant-energy or constant-momentum acceleration modes. A decreasing electric field distribution in the ion-accelerating region makes it possible to direct ions onto a space-focal plane in either modes of operation. Ions produced in the constant-momentum mode have velocities and, thus, flight times that are linearly dependent on mass and kinetic energies that are inversely dependent on mass. The linear mass dispersion doubles mass resolving power of ions accelerated with space-focusing conditions in constant-momentum mode. The mass-dependent kinetic energy is exploited to disperse ions according to mass in a simple kinetic energy filter constructed from two closely spaced, oblique ion reflectors. Focusing velocity of ions of the same mass can substantially improve ion selection for subsequent post source decay or tandem time-of-flight analyses. (J Am Soc Mass Spectrom 2007, 18, 92-101)

Recent Advances in Instrumental Approaches to Time‐of‐flight Mass Spectrometry

“…In both cases, theoretical analysis predicted that the mass resolution of CMA-TOFMS should be competitive with, or better than, that obtainable in conventional designs. Santacruz et al described a MALDI-TOFMS that used a novel non-linear acceleration field and that could be operated in either CEA-TOFMS or CMA-TOFMS modes (Santacruz et al, 2007). By using impulse acceleration within an electric field that decreased in strength with distance, the authors suggested that a space-focusing capability could be achieved.…”

Natural Dyes from Mortiño (Vaccinium floribundum) as Sensitizers in Solar Cells

“…The filtrates were combined with 10 mg/mL of α-cyano-4-hydroxycinnamic acid (CHCA) matrix dissolved in acetonitrile with 0.01% TFA v/v (10:40), these were deposited on stainless steel plates and dried for MALDI-Tof analysis. The spectrometer was built in the Physics Department of Escuela Politécnica Nacional (EPN, Quito, Ecuador) using the guidelines of [31]. A 337-nm nitrogen laser ionization (Spectra-Physics 337201-001) was used, and the signals were recorded in an oscilloscope (Tektronix TDS 5052).…”

In pursuit of resolution in time‐of‐flight mass spectrometry: A historical perspective

“…The socalled curved-field ion mirror was promoted by Cotter and also Doroshenko (Doroshenko & Cotter, 1999;Doroshenko, 2000). Constant momentum TOF was developed by Santacruz et al (2006). Sysoev et al (1966) has described electrostatic sectors , and both Bakker (1971) and Poschenrieder (1972) addressed time-focusing with sectors.…”

“…This was unfortunate, in as much as TOF under constant momentum acceleration does not suffer from “turn‐around effect,” and also offers a linear dependence of flight time on mass‐to‐charge. More attention has been given to constant momentum acceleration in the last 15 years (Ioanoviciu, ; Santacruz et al, ; Dennis et al, 2013).…”