Monoenergetic source of kilodalton ions from Taylor cones of ionic liquids

Journal Article · Sun Apr 15 00:00:00 EDT 2007 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2717858· OSTI ID:20982829

Larriba, C; Castro, S; Lozano, P ^[1]

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1. Department of Mechanical Engineering, Yale University, New Haven, Connecticut 06520-8286 (United States)

The ionic liquid ion sources (ILISs) recently introduced by Lozano and Martinez Sanchez [J. Colloid Interface Sci. 282, 415 (2005)], based on electrochemically etched tungsten tips as emitters for Taylor cones of ionic liquids (ILs), have been tested with ionic liquids [A{sup +}B{sup -}] of increasing molecular weight and viscosity. These ILs have electrical conductivities well below 1 S/m and were previously thought to be unsuitable to operate in the purely ionic regime because their Taylor cones produce mostly charged drops from conventional capillary tube sources. Strikingly, all the ILs tried on ILIS form charged beams composed exclusively of small ions and cluster ions A{sup +}(AB){sub n} or B{sup -}(AB){sub n}, with abundances generally peaking at n=1. Particularly interesting are the positive and negative ion beams produced from the room temperature molten salts 1-methyl-3-pentylimidazolium tris(pentafluoroethyl) trifluorophosphate (C{sub 5}MI-(C{sub 2}F{sub 5}){sub 3}PF{sub 3}) and 1-ethyl-3-methylimidazolium bis(pentafluoroethyl) sulfonylimide (EMI-(C{sub 2}F{sub 5}SO{sub 3}){sub 2}N). We extend to these heavier species the previous conclusions from Lozano and Martinez Sanchez on the narrow energy distributions of the ion beams. In combination with suitable ILs, this source yields nanoamphere currents of positive and negative monoenergetic molecular ions with masses exceeding 2000 amu. Potential applications are in biological secondary ion mass spectrometry, chemically assisted high-resolution ion beam etching, and electrical propulsion. Advantages of the ILISs versus similar liquid metal ion sources include the possibility to form negative as well as positive ion beams and a much wider range of ion compositions and molecular masses.

• OSTI ID: 20982829
• Journal Information: Journal of Applied Physics, Vol. 101, Issue 8; Other Information: DOI: 10.1063/1.2717858; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
ANIONS
CAPILLARIES
CATIONS
COLLOIDS
ELECTRIC CONDUCTIVITY
ELECTROCHEMISTRY
ENERGY SPECTRA
ETCHING
ION BEAMS
ION PAIRS
ION SOURCES
LIQUID METALS
MASS SPECTROSCOPY
MOLECULAR IONS
MOLTEN SALTS
ORGANIC COMPOUNDS
TEMPERATURE RANGE 0273-0400 K
TUNGSTEN
VISCOSITY