Soft X-ray spectroscopy and microscopy using a table-top ...a table-top laser-induced plasma source...
Transcript of Soft X-ray spectroscopy and microscopy using a table-top ...a table-top laser-induced plasma source...
Soft X-ray spectroscopy and microscopy using
a table-top laser-induced plasma sourceM. Müller, J. Holburg, K. MannLaser-Laboratorium Göttingen e. V., Hans-Adolf-Krebs-Weg 1, D-37077 Göttingen
Introduction
The progress in development of
laboratory-scale soft X-ray sources in
recent years has enabled experimental
techniques that could be performed
before almost exclusively at
synchrotrons. Here, we present two
applications of a compact, long-term
stable and nearly debris-free laser-
induced plasma source based on a
pulsed gas jet target: Broadband
radiation is used for polychromatic
absorption spectroscopy in the ‘waterwindow´ spectral region, investigating
the fine-structure of absorption edges
that reveals information e.g. about type
of bonds, oxidation states and
coordination. The performance of this
NEXAFS spectrometer is demonstrated
for different organic and inorganic
samples probing the K- and L-edges of
carbon, calcium, oxygen, manganese,
and iron. On the other hand,
monochromatic radiation at a
wavelength of λ = 2.88 nm produced
from a nitrogen plasma is employed for
soft X-ray transmission microscopy,
accomplishing a spatial resolution of
about 50 nm.
Research Results
References / Funding
NEXAFS spectroscopy
Polychromatic radiation (λ = 1 – 5 nm) [6,7]
Elemental and compositional analysis (C, Ca, N, O, Mn, Fe, Pr, …)
Pump-probe experiments (proof of principle) [8]
Compact soft X-ray microscope [4,5]
Monochromatic radiation at λ = 2.88 nm
Spatial resolution ≈ 50 nm
Bacterium Deinococcus
radiodurans
1 m
≈ 108 photons/pulse
(FOV 100 µm)
Alga Trachelomonas
oblonga
30 mm
[1] M. Müller, F. C. Kühl, P. Großmann, P. Vrba, and K. Mann. Emission properties of ns and ps laser-induced soft x-ray
sources using pulsed gas jets. Optics Expr. 21(10), 2013.
[2] T. Mey, M. Rein, P. Großmann, and K. Mann. Brilliance improvement of laser-produced soft x-ray plasma by a
barrel shock. New J. Phys. 14(7), 2012.
[3] J. Holburg, M. Müller, S. Wieneke, and K. Mann. Brilliance improvement of laser-produced EUV/SXR plasmas
based on pulsed gas jets. JVST A, submitted, 2018.
[4] M. Müller, T. Mey, J. Niemeyer, and K. Mann. Table-top soft x-ray microscope using laser-induced plasma from a
pulsed gas jet. Optics Expr. 22(19), 2014.
[5] M. Müller, T. Mey, J. Niemeyer, M. Lorenz, and K. Mann. Table-top soft x-ray microscopy with a laser-induced
plasma source based on a pulsed gas-jet. AIP Conf. Proc. 1764, 2016.
[6] C. Peth, F. Barkusky, and K. Mann. Near-edge X-ray absorption fine structure Measurements using a laboratory-
scale XUV source. J. Phys. D 41, 2008.
[7] J. Sedlmair. Soft X-ray Spectromicroscopy of Environmental and Biological Samples. PhD thesis, Universität
Göttingen, 2011.
[8] P. Großmann, I. Rajkovic, R. More, J. Norpoth, S. Techert, C. Jooss, and K. Mann. Time-resolved near-edge x-ray
absorption fine structure spectroscopy on photo-induced phase transitions using a table-top soft-x-ray
spectrometer. Rev. Sci. Instrum. 83(5), 2012.
[9] F. Kühl, M. Müller, M. Schellhorn, S. Wieneke, K. Eusterhues, and K. Mann. Near-edge x-ray absorption fine
structure spectroscopy at atmospheric pressure with a table-top laser-induced soft x-ray source. JVST A, 34(4),
2016.
Laser-driven soft X-ray source
Low debris generation
Long-term stability
Continuous supply of target material
Improvement of plasma brilliance
Enhancement of local gas density by
• generation of a “barrel-shock” [2]
• high pressure gas jet (20 bar 200 bar)
• angular emission characteristics [3]
Employment of high power lasers with
• picosecond pulse duration [1]
• high repetition rate (< 10 ps, > 1 kHz, > 100 W)
Peak brilliance at 2.88 nm
≈ 1018 ph/(s*mrad2*mm2) [1]
Soft X-ray coherent diffractive imaging (CDI) at λ = 2.88 nm
Convolution of far-field diffraction pattern with Gaussian function
Van Cittert-Zernike theorem: lc ≈ 13.3 µm
Diffraction data: lc,exp ≈ 13.2 µm
Methods
average electron
temperature
average electron
density
ns laser 50.3 eV 66.3 eV
ps laser 7.0·1019 e/cm³ 22.4·1019 e/cm³
Inte
nsity
[a.u
.]
0
1
Pinhole camera image
of nitrogen plasma
nitrogen emission spectrum
sample: 10 µm pinhole
Samples under atmospheric conditions [9]
Photon energy [eV] Photon energy [eV]Photon energy [eV]
Photon energy [eV] higher overall intensity
shift to higher photon energies
Photon energy [eV]
Photon energy [eV]Photon energy [eV]
Op
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[a.u
.]O
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l d
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Op
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Optical density
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Optical density
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.]
Inte
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Inte
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Photon energy [eV]