Radicals are prevalent in gas-phase environments such as the atmosphere, combustion systems, and the interstellar medium. To understand the properties of the processes occurring in these environments, it is helpful to study radical reaction systems in isolation—thereby avoiding competing reactions from impurities. There are very few methods for generating a pure beam of gas-phase radicals, and those that do exist involve complex setups. Here, we provide a straightforward and versatile solution. A magnetic radical filter (MRF), composed of four Halbach arrays and two skimming blades, can generate a beam of velocity-selected low-field-seeking hydrogen atoms. As there is no line-of-sight through the device, all species that are unaffected by the magnetic fields are physically blocked; only the target radicals are successfully guided around the skimming blades. The positions of the arrays and blades can be adjusted, enabling the velocity distribution of the beam (and even the target radical species) to be modified. The MRF is employed as a stand-alone device—filtering radicals directly from the source. Our findings open up the prospect of studying a range of radical reaction systems with a high degree of control over the properties of the radical reactants.
REFERENCES
1.
J.
Thiebaud
, A.
Aluculesei
, and C.
Fittschen
, “Formation of HO2 radicals from the photodissociation of H2O2 at 248 nm
,” J. Chem. Phys.
126
, 186101
(2007
).2.
L.
Ghassemzadeh
, T. J.
Peckham
, T.
Weissbach
, X.
Luo
, and S.
Holdcroft
, “Selective formation of hydrogen and hydroxyl radicals by electron beam irradiation and their reactivity with perfluorosulfonated acid ionomer
,” J. Am. Chem. Soc.
135
, 15923
–15932
(2013
).3.
J.
Slevin
and W.
Stirling
, “Radio frequency atomic hydrogen beam source
,” Rev. Sci. Instrum.
52
, 1780
–1782
(1981
).4.
W.
Gerlach
and O.
Stern
, “Der experimentelle nachweis des magnetischen moments des silberatoms
,” Z. Phys.
8
, 110
–111
(1922
).5.
W.
Gerlach
and O.
Stern
, “Der experimentelle nachweis der richtungsquantelung im magnetfeld
,” Z. Phys.
9
, 349
–352
(1922
).6.
G.
Breit
and I. I.
Rabi
, “Measurement of nuclear spin
,” Phys. Rev.
38
, 2082
–2083
(1931
).7.
I. I.
Rabi
and V. W.
Cohen
, “Measurement of nuclear spin by the method of molecular beams. The nuclear spin of sodium
,” Phys. Rev.
46
, 707
–712
(1934
).8.
J. M. B.
Kellogg
, I. I.
Rabi
, N. F.
Ramsey
, Jr., and J. R.
Zacharias
, “The magnetic moments of the proton and the deuteron. The radiofrequency spectrum of H2 in various magnetic fields
,” Phys. Rev.
56
, 728
–743
(1939
).9.
K.
Halbach
, “Design of permanent multipole magnets with oriented rare earth cobalt material
,” Nucl. Instrum. Methods
169
, 1
–10
(1980
).10.
B.
Ghaffari
, J. M.
Gerton
, W. I.
McAlexander
, K. E.
Strecker
, D. M.
Homan
, and R. G.
Hulet
, “Laser-free slow atom source
,” Phys. Rev. A
60
, 3878
–3881
(1999
).11.
A.
Goepfert
, F.
Lison
, R.
Schütze
, R.
Wynands
, D.
Haubrich
, and D.
Meschede
, “Efficient magnetic guiding and deflection of atomic beams with moderate velocities
,” Appl. Phys. B
69
, 217
–222
(1999
).12.
M.
Greiner
, I.
Bloch
, T. W.
Hänsch
, and T.
Esslinger
, “Magnetic transport of trapped cold atoms over a large distance
,” Phys. Rev. A
63
, 031401(R)
(2001
).13.
K.
Dulitz
and T. P.
Softley
, “Velocity-selected magnetic guiding of Zeeman-decelerated hydrogen atoms
,” Eur. Phys. J. D
70
, 19
(2016
).14.
K.
Hayashi
, N.
Sakudo
, T.
Noda
, A.
Takeda
, K.
Fujimura
, and N.
Shimizu
, “A new method for generating a refined beam of neutral radicals
,” Nucl. Instrum. Methods Phys. Res., Sect. B
127
, 918
–921
(1997
).15.
G.
Borodi
, A.
Luca
, and D.
Gerlich
, “Reactions of with H, H2 and deuterated analogues
,” Int. J. Mass Spectrom.
280
, 218
–225
(2009
).16.
D.
Watanabe
, H.
Ohoyama
, T.
Matsumura
, and T.
Kasai
, “Steric effect in the energy transfer reaction of Ar (3P2) + N2
,” J. Chem. Phys.
125
, 084316
(2006
).17.
H.
Ohoyama
and S.
Maruyama
, “Alignment effect of N2 (A) in the energy transfer reaction of aligned N2 (A) + NO (X2Π) → NO (A2Σ+) + N2 (X)
,” J. Phys. Chem. A
116
, 6685
–6692
(2012
).18.
D.
Watanabe
, H.
Ohoyama
, T.
Matsumura
, and T.
Kasai
, “Characterization of an oriented metastable atom source based on a magnetic hexapole
,” Eur. Phys. J. D
38
, 219
–223
(2006
).19.
M.
Kirste
, H.
Haak
, G.
Meijer
, and S. Y. T.
van de Meerakker
, “A compact hexapole state-selector for NO radicals
,” Rev. Sci. Instrum.
84
, 073113
(2013
).20.
M. C.
van Beek
, J. J.
ter Meulen
, and M. H.
Alexander
, “Rotationally inelastic collisions of OH(X2Π) + Ar. I. State-to-state cross sections
,” J. Chem. Phys.
113
, 628
–636
(2000
).21.
C. J.
Eyles
, M.
Brouard
, H.
Chadwick
, B.
Hornung
, B.
Nichols
, C.-H.
Yang
, J.
Kłos
, F. J.
Aoiz
, A.
Gijsbertsen
, A. E.
Wiskerke
, and S.
Stolte
, “Fully Λ-doublet resolved state-to-state differential cross-sections for the inelastic scattering of NO(X) with Ar
,” Phys. Chem. Chem. Phys.
14
, 5403
–5419
(2012
).22.
N.
Vanhaecke
, U.
Meier
, M.
Andrist
, B. H.
Meier
, and F.
Merkt
, “Multistage Zeeman deceleration of hydrogen atoms
,” Phys. Rev. A
75
, 031402
(2007
).23.
E.
Narevicius
, C. G.
Parthey
, A.
Libson
, J.
Narevicius
, I.
Chavez
, U.
Even
, and M. G.
Raizen
, “An atomic coilgun: Using pulsed magnetic fields to slow a supersonic beam
,” New J. Phys.
9
, 358
(2007
).24.
E.
Narevicius
, A.
Libson
, C. G.
Parthey
, I.
Chavez
, J.
Narevicius
, U.
Even
, and M. G.
Raizen
, “Stopping supersonic beams with a series of pulsed electromagnetic coils: An atomic coilgun
,” Phys. Rev. Lett.
100
, 093003
(2008
).25.
A. W.
Wiederkehr
, S. D.
Hogan
, and F.
Merkt
, “Phase stability in a multistage Zeeman decelerator
,” Phys. Rev. A
82
, 043428
(2010
).26.
A. W.
Wiederkehr
, M.
Motsch
, S. D.
Hogan
, M.
Andrist
, H.
Schmutz
, B.
Lambillotte
, J. A.
Agner
, and F.
Merkt
, “Multistage Zeeman deceleration of metastable neon
,” J. Chem. Phys.
135
, 214202
(2011
).27.
E.
Lavert-Ofir
, S.
Gersten
, A. B.
Henson
, I.
Shani
, L.
David
, J.
Narevicius
, and E.
Narevicius
, “A moving magnetic trap decelerator: A new source of cold atoms and molecules
,” New J. Phys.
13
, 103030
(2011
).28.
T.
Momose
, Y.
Liu
, S.
Zhou
, P.
Djuricanin
, and D.
Carty
, “Manipulation of translational motion of methyl radicals by pulsed magnetic fields
,” Phys. Chem. Chem. Phys.
15
, 1772
–1777
(2013
).29.
K.
Dulitz
, M.
Motsch
, N.
Vanhaecke
, and T. P.
Softley
, “Getting a grip on the transverse motion in a Zeeman decelerator
,” J. Chem. Phys.
140
, 104201
(2014
).30.
M.
Motsch
, P.
Jansen
, J. A.
Agner
, H.
Schmutz
, and F.
Merkt
, “Slow and velocity-tunable beams of metastable He2 by multistage Zeeman deceleration
,” Phys. Rev. A
89
, 043420
(2014
).31.
J.
Toscano
, A.
Tauschinsky
, K.
Dulitz
, C. J.
Rennick
, B. R.
Heazlewood
, and T. P.
Softley
, “Zeeman deceleration beyond periodic phase space stability
,” New J. Phys.
19
, 083016
(2017
).32.
T.
Cremers
, S.
Chefdeville
, V.
Plomp
, N.
Janssen
, E.
Sweers
, and S. Y. T.
van de Meerakker
, “Multistage Zeeman deceleration of atomic and molecular oxygen
,” Phys. Rev. A
98
, 033406
(2018
).33.
J.
Toscano
, L. Y.
Wu
, M.
Hejduk
, and B. R.
Heazlewood
, “Evolutionary algorithm optimization of Zeeman deceleration: Is it worthwhile for longer decelerators?
,” J. Phys. Chem. A
123
, 5388
–5394
(2019
).34.
V.
Plomp
, Z.
Gao
, T.
Cremers
, M.
Besemer
, and S. Y. T.
van de Meerakker
, “High-resolution imaging of molecular collisions using a Zeeman decelerator
,” J. Chem. Phys.
152
, 091103
(2020
).35.
J.
Toscano
, C. J.
Rennick
, T. P.
Softley
, and B. R.
Heazlewood
, “A magnetic guide to purify radical beams
,” J. Chem. Phys.
149
, 174201
(2018
).36.
J.
Toscano
, M.
Hejduk
, H. G.
McGhee
, and B. R.
Heazlewood
, “Manipulating hydrogen atoms using permanent magnets: Characterisation of a velocity-filtering guide
,” Rev. Sci. Instrum.
90
, 033201
(2019
).© 2020 Author(s).
2020
Author(s)
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