TU Berlin

AG Kanngießerns-NEXAFS with soft X-rays

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Laser-produced plasma source

The concept of hitting a target with a focused, short-pulse, high average power laser beam in order to obtain tailored X-ray pulses has been introduced during the last two decades. Due to recent improvements in high average power solid state lasers producing short pulses in the ns or sub-ns range, laser induced plasmas covering a broad range of photon energies in the soft and hard x-ray region are nowadays used as laboratory X-ray sources. Up until now the main focus in the soft X-ray region has been laid on X-ray sources for extreme ultraviolet (EUV)-lithography at 13.5 nm and X-ray sources in the water window (2.3 – 4.4 nm) for the analysis of biological samples.

In the last years a laser-produced plasma (LPP) source was developed together with the Max-Born-Institute (MBI), Berlin, and the company Bestec GmbH. This soft X-ray source yields radiation from 100 to 1200 eV with stable operating conditions. The 1 keV region is especially interesting for the investigation of L-edges of transition metals, thus, enabling analysis of technological samples with a depth resolution in the nm-regime. The lack of suitable X-ray tubes in this energetic region and factors like beam time restrictions at synchrotron sources will render this new instrument into a valuable tool for X-ray emission and absorption spectroscopy as well as for example X-ray metrology.

Laser and Plasma System

The BLiX-LPP source has two flexible beamlines, in this example two XAS experiments are performed simultaneously; the laser system is situated in a clean room environment

The used laser is a high average power commercial Yb:YAG – thin disk laser system (TRUMPF Laser Technology) which is modified with a pulsed distributed Bragg reflector (DBR) seed-diode in order to obtain optimal pulse parameters. This seed-diode was developed in a cooperation with the Ferdinand-Braun-Institut für Höchstfrequenztechnik (FBH) and PicoLas GmbH. In normal operation mode the system delivers 1.2 ns laser pulses with 100 Hz repetition rate, 250 mJ single pulse energy and an M² < 1.2. In the plasma interaction chamber the laser pulses are focussed onto a rotating and translating metal cylinder, forming a small hot dense plasma, which emits the desired soft X-rays. A real-time feedback system based on a pinhole camera using a 4 quadrant XUV diode ensures source position stability, while the laser and the emission intensity are monitored during measurements. Two beamlines offer the possibility of two simultaneous experiments.   Point of contact: Ioanna Mantouvalou Relevant publications: I. Mantouvalou, R. Jung, J. Tuemmler, H. Legall, T. Bidu, H. Stiel, W. Malzer, B. Kanngießer, and W. Sandner, Review of Scientific Instruments 82, 066103 (2011) I. Mantouvalou, K. Witte, D. Grötzsch, M. Neitzel, S. Günther, J. Baumann, R. Jung, H. Stiel, B. Kanngießer, and W. Sandner, Review of Scientific Instruments 86, 035116 (2015)

Single shot NEXAFS

The broad spectral emission enables X-ray absorption spectroscopy (XAS) in one single shot. Through a collaboration with a group of Prof. Erko at the HZB adapted reflection zone plates were designed and manufactured which render NEXAFS spectroscopy at the C and N K edge with a resolving power of E/ΔE=950 feasible. First experiments on reference samples have proven the excellent efficiency of the setup and current research focusses on the investigation of bio-molecules.


Point of contact: Ioanna Mantouvalou, Katharina Witte, Adrian Jonas

Relevant publications:

I. Mantouvalou, K. Witte, W. Martyanov, A. Jonas, D. Grötzsch, C. Streeck, H. Löchel, I. Rudolph, A. Erko, H. Stiel, and B. Kanngießer, Applied Physics Letters 108, 201106 (2016)



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