Hostname: page-component-7c8c6479df-5xszh Total loading time: 0 Render date: 2024-03-26T15:16:23.417Z Has data issue: false hasContentIssue false

Ultracold Electron Source for Single-Shot, Ultrafast Electron Diffraction

Published online by Cambridge University Press:  03 July 2009

S.B. van der Geer*
Affiliation:
Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
M.J. de Loos
Affiliation:
Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
E.J.D. Vredenbregt
Affiliation:
Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
O.J. Luiten
Affiliation:
Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
*
Corresponding author. E-mail: sgeer@pulsar.nl
Get access

Abstract

Ultrafast electron diffraction (UED) enables studies of structural dynamics at atomic length and timescales, i.e., 0.1 nm and 0.1 ps, in single-shot mode. At present UED experiments are based on femtosecond laser photoemission from solid state cathodes. These photoemission sources perform excellently, but are not sufficiently bright for single-shot studies of, for example, biomolecular samples. We propose a new type of electron source, based on near-threshold photoionization of a laser-cooled and trapped atomic gas. The electron temperature of these sources can be as low as 10 K, implying an increase in brightness by orders of magnitude. We investigate a setup consisting of an ultracold electron source and standard radio-frequency acceleration techniques by GPT tracking simulations. The simulations use realistic fields and include all pairwise Coulomb interactions. We show that in this setup 120 keV, 0.1 pC electron bunches can be produced with a longitudinal emittance sufficiently small for enabling sub-100 fs bunch lengths at 1% relative energy spread. A transverse root-mean-square normalized emittance of εx = 10 nm is obtained, significantly better than from photoemission sources. Correlations in transverse phase-space indicate that the transverse emittance can be improved even further, enabling single-shot studies of biomolecular samples.

Type
Special Section: Ultrafast Electron Microscopy
Copyright
Copyright © Microscopy Society of America 2009

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Barnes, J. & Hut, P. (1986). A hierarchical O(N log N) force-calculation algorithm. Nature 324, 446449.CrossRefGoogle Scholar
Billen, J.H. & Young, L.M. (2003). Poisson superfish. Report LA-UR-96-1834, Los Alamos National Laboratory.Google Scholar
Carlsten, B.E. (1989). New photoelectric injector design for the Los Alamos National Laboratory XUV FEL accelerator. Nucl Instrum Methods Phys Res A 285, 313319.CrossRefGoogle Scholar
Chen, Y.C., Simien, C.E., Laha, S., Gupta, P., Martinez, Y.N., Mickelson, P.G., Nagel, S.B. & Killian, T.C. (2004). Electron screening and kinetic-energy oscillations in a strongly coupled plasma. Phys Rev Lett 93, 265003.CrossRefGoogle Scholar
Claessens, B.J., Reijnders, M.P., Taban, G., Luiten, O.J. & Vredenbregt, E.J.D. (2007). Cold electron and ion beams generated from trapped atoms. Phys Plasmas 14, 093101.CrossRefGoogle Scholar
Claessens, B.J., van der Geer, S.B., Taban, G., Vredenbregt, E.J.D. & Luiten, O.J. (2005). Ultracold electron source. Phys Rev Lett 95, 164801.CrossRefGoogle ScholarPubMed
Dwyer, R., Hebeisen, C.T., Ernstorfer, R., Harb, M., Deyirmenjian, V.B., Jordan, R.E. & Miller, R.J.D. (2006). Femtosecond electron diffraction: “Making the molecular movie.” Phil Trans R Soc 364, 741778.CrossRefGoogle Scholar
Hastings, J.B., Rudakov, F.M., Dowell, D.H., Schmerge, J.F., Cardoza, J.D., Castro, J.M., Gierman, S.M., Loos, H. & Weber, P.M. (2006). Appl Phys Lett 89, 184109.CrossRefGoogle Scholar
Kiewiet, F.B., Kemper, A.H., Luiten, O.J., Brussaard, G.J.H. & van der Wiel, M.J. (2002). Femtosecond synchronization of a 3 GHz rf oscillator to a mode-locked Ti:Sapphire laser. Nucl Instrum Methods Phys Res A 484, 619624.CrossRefGoogle Scholar
Killian, T.C., Kulin, S., Bergeson, S.D., Orozco, L.A., Orzel, C. & Rolston, S.L. (1999). Creation of an ultracold neutral plasma. Phys Rev Lett 83, 47764779. [For reviews, see Gallagher, T.F. et al. (2003). Back and forth between Rydberg atoms and ultracold plasmas. J Opt Soc Am B 20, 1091–1097; Killian, T.C. (2007). Ultracold neutral plasmas. Science 316, 705–708.]CrossRefGoogle Scholar
Kuzmin, S.G. & O'Neil, T.M. (2002). Numerical simulation of ultracold plasmas: How rapid intrinsic heating limits the development of correlation. Phys Rev Lett 88, 065003.CrossRefGoogle ScholarPubMed
Metcalf, H. & van der Straten, P. (1999). Laser Cooling and Trapping. New York: Springer.CrossRefGoogle Scholar
Musumeci, P., Moody, J.T. & Scoby, C.M. (2008). Relativistic electron diffraction at the UCLA Pegasus photoinjector laboratory. Ultramicroscopy 108, 14501453.CrossRefGoogle ScholarPubMed
Serafini, L. & Rosenzweig, J.B. (1997). Envelope analysis of intense relativistic quasilaminar beams in rf photoinjectors:mA theory of emittance compensation. Phys Rev E 55, 75657590.CrossRefGoogle Scholar
Siwick, B.J., Dwyer, J.R., Jordan, R.E. & Miller, R.J.D. (2003). An atomic-level view of melting using femtosecond electron diffraction. Science 302, 13821385.CrossRefGoogle ScholarPubMed
Srinivasan, R., Lobastov, V.A., Ruan, C.-Y. & Zewail, A.H. (2003). Ultrafast electron diffraction (UED) a new development for the 4D determination of transient molecular structures. Helv Chim Act 86, 17631838.CrossRefGoogle Scholar
Taban, G., Reijnders, M.P., Bell, S.C., van der Geer, S.B., Luiten, O.J. & Vredenbregt, E.J.D. (2008). Design and validation of an accelerator for an ultracold electron source. Phys Rev ST-AB 11, 050102.Google Scholar
van der Geer, S.B. & de Loos, M.J. (2009). The general particle tracer code. Available at http://www.pulsar.nl/gpt.Google Scholar
van Oudheusden, T., de Jong, E.F., van der Geer, S.B., Op 't Root, W.P.E.M., Luiten, O.J. & Siwick, B.J. (2007). Electron source concept for single-shot sub-100 fs electron diffraction in the 100 keV range. J Appl Phys 102, 093501.CrossRefGoogle Scholar
Ximen, Jiye (1986). Aberration Theory in Electron and Ion Optics. New York: Academic Press.Google Scholar