A Bradbury–Nielsen shutter (or Bradbury–Nielsen gate) is a type of electrical ion gate, which was first proposed in an article by Norris Bradbury and Russel A. Nielsen, where they used it as an electron filter.[1] Today they are used in the field of mass spectrometry where they are used in both TOF mass spectrometers and in ion mobility spectrometers[2] , as well as Hadamard transform mass spectrometers (a variant of TOF-MS).[3][4] The Bradbury–Nielsen shutter is ideal for injecting short pulses of ions and can be used to improve the mass resolution of TOF instruments by reducing the initial pulse size as compared to other methods of ion injection.
Schematic top view of a Bradbury-Nielsen shutter with voltages on (deflecting).
The concept behind the Bradbury–Nielsen shutter is to apply a high frequencyvoltage in a 180° out-of-phase manner to alternate wires in a grid which is orthogonal to the path of the ion beam. This results in charged particles only passing directly through the shutter at certain times in the voltage phase (φ=nπ/2), when the potential difference between the grid wires is zero. At other times the ion beam is deflected to some angle by the potential difference between the neighboring wires. This deflection is divergent with ions that pass through alternate slits being deflected in opposite directions. The maximum deflection angle [4] can be calculated by
tan α = k Vp / V0
where α is the deflection angle, k is a deflection constant, Vp is the wire voltage (+Vp on one wire set and -Vp on the other), and V0 is the ion acceleration voltage in eV. The deflection constant k can be calculated by
k = π / 2ln[cot(πR/2d)]
where R is the wire radius and d is the wire spacing.
^Norris E. Bradbury & Russel A. Nielsen (1936). "Absolute Values of the Electron Mobility in Hydrogen". Physical Review. 49 (5): 388–93. Bibcode:1936PhRv...49..388B. doi:10.1103/PhysRev.49.388.
^Szumlas, Andrew W; Hieftje, Gary M (2005). . Rev. Sci. Instrum. 76 (8). AIP. Bibcode:2005RScI...76h6108S. doi:10.1063/1.2006308. Archived from the original on 2011-09-29.
^Joel R. Kimmel; Friedrich Engelke & Richard N. Zare (2001). "Novel method for the production of finely spaced Bradbury–Nielson gates". Review of Scientific Instruments. 72 (12): 4354–4357. Bibcode:2001RScI...72.4354K. doi:10.1063/1.1416109.
^ abOh Kyu Yoon; Ignacio A. Zuleta; Matthew D. Robbins; Griffin K. Barbula & Richard N. Zare (2007). "Simple Template-Based Method to Produce Bradbury-Nielsen Gates". Journal of the American Society for Mass Spectrometry. 18 (11): 1901–1908. doi:10.1016/j.jasms.2007.07.030. PMID 17827033.
^US patent 7176452, Zuleta I., Zare R. & Richard N. Zare, "Microfabricated beam modulation device", issued 2007-02-13, assigned to The Board of Trustees of the Leland Stanford Junior University (Palo Alto, CA)
bradbury, nielsen, shutter, bradbury, nielsen, gate, type, electrical, gate, which, first, proposed, article, norris, bradbury, russel, nielsen, where, they, used, electron, filter, today, they, used, field, mass, spectrometry, where, they, used, both, mass, s. A Bradbury Nielsen shutter or Bradbury Nielsen gate is a type of electrical ion gate which was first proposed in an article by Norris Bradbury and Russel A Nielsen where they used it as an electron filter 1 Today they are used in the field of mass spectrometry where they are used in both TOF mass spectrometers and in ion mobility spectrometers 2 as well as Hadamard transform mass spectrometers a variant of TOF MS 3 4 The Bradbury Nielsen shutter is ideal for injecting short pulses of ions and can be used to improve the mass resolution of TOF instruments by reducing the initial pulse size as compared to other methods of ion injection Schematic top view of a Bradbury Nielsen shutter with voltages on deflecting Contents 1 Theory of operation 2 Micromachined ion gates 3 References 4 See alsoTheory of operation editThe concept behind the Bradbury Nielsen shutter is to apply a high frequency voltage in a 180 out of phase manner to alternate wires in a grid which is orthogonal to the path of the ion beam This results in charged particles only passing directly through the shutter at certain times in the voltage phase f np 2 when the potential difference between the grid wires is zero At other times the ion beam is deflected to some angle by the potential difference between the neighboring wires This deflection is divergent with ions that pass through alternate slits being deflected in opposite directions The maximum deflection angle 4 can be calculated bytan a k Vp V0where a is the deflection angle k is a deflection constant Vp is the wire voltage Vp on one wire set and Vp on the other and V0 is the ion acceleration voltage in eV The deflection constant k can be calculated byk p 2ln cot pR 2d where R is the wire radius and d is the wire spacing Micromachined ion gates editA Bradbury Nielsen Gate micromachined from a silicon on insulator wafer has been reported 5 6 References edit Norris E Bradbury amp Russel A Nielsen 1936 Absolute Values of the Electron Mobility in Hydrogen Physical Review 49 5 388 93 Bibcode 1936PhRv 49 388B doi 10 1103 PhysRev 49 388 Szumlas Andrew W Hieftje Gary M 2005 Design and construction of a mechanically simple interdigitated wire ion gate Rev Sci Instrum 76 8 AIP Bibcode 2005RScI 76h6108S doi 10 1063 1 2006308 Archived from the original on 2011 09 29 Joel R Kimmel Friedrich Engelke amp Richard N Zare 2001 Novel method for the production of finely spaced Bradbury Nielson gates Review of Scientific Instruments 72 12 4354 4357 Bibcode 2001RScI 72 4354K doi 10 1063 1 1416109 a b Oh Kyu Yoon Ignacio A Zuleta Matthew D Robbins Griffin K Barbula amp Richard N Zare 2007 Simple Template Based Method to Produce Bradbury Nielsen Gates Journal of the American Society for Mass Spectrometry 18 11 1901 1908 doi 10 1016 j jasms 2007 07 030 PMID 17827033 Zuleta IA Barbula GK Robbins MD Yoon OK Zare RN 2007 Micromachined bradbury nielsen gates Anal Chem 79 23 9160 5 doi 10 1021 ac071581e PMID 17966990 US patent 7176452 Zuleta I Zare R amp Richard N Zare Microfabricated beam modulation device issued 2007 02 13 assigned to The Board of Trustees of the Leland Stanford Junior University Palo Alto CA See also editIon mobility spectrometer Time of flight Retrieved from https en wikipedia org w index php title Bradbury Nielsen shutter amp oldid 1049177695, wikipedia, wiki, book, books, library,
