A Constant-Momentum/Energy-Selector Time-of-Flight Mass Spectrometer

• Published in: Journal of the American Society for Mass Spectrometry Vol. 18; no. 1; pp. 92 - 101
• Main Authors: Santacruz, C.P., Håkansson, P., Barofsky, D.F., Piyadasa, C.K.G.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 2007; Elsevier Science; Springer Nature B.V
• Subjects: Angiotensin I - analysis; Dispersion; Electric power distribution; Exact sciences and technology; Focal plane; Fysik; Gonadotropin-Releasing Hormone - analysis; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Ionization; Ions; Kinetic energy; Kinetics; Mass spectrometers and related techniques; Mass spectrometry; NATURAL SCIENCES; NATURVETENSKAP; Neurotensin - analysis; Peptides - analysis; Physics; Reflectors; Resolution; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - instrumentation; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - methods; Substance P - analysis; Performance evaluation; Prototype; Ion sources; Instrumentation; Time-of-flight method; Mass spectroscopy; Matrix assisted laser desorption ionization
• ISSN: 1044-0305; 1879-1123; 1879-1123
• DOI: 10.1016/j.jasms.2006.08.020

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.