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Joint Research Group - SyncLab
Sample cells
At BLiX we develop adapted sample environments for measurements using soft and hard X-rays. During ~15 years of development, Daniel Grötzsch has designed and put into operation concepts for various measurement needs, including investigations of liquids, gases, battery stacks, with pressure and temperature control.
Selected publications:
A sealable ultrathin window sample cell for the study of liquids by means of soft X-ray spectroscopy
Abstract:
A new sample cell concept for the analysis of liquids or solid-liquid interfaces using soft X-ray spectroscopy is presented, which enables the complete sealing of the cell as well as the transport into vacuum via, for example, a load-lock system. The cell uses pressure monitoring and active as well as passive pressure regulation systems, thereby facilitating the full control over the pressure during filling, sealing, evacuation, and measurement. The cell design and sample preparation as well as the crucial sealing procedure are explained in detail. As a first proof-of-principle experiment, successful nitrogen K-edge fluorescence yield near-edge X-ray absorption fine structure experiments of a biomolecular solution are presented. For this purpose, it is shown that the careful evaluation of all involved parameters, such as window type or photon flux, is desirable for optimizing the experimental result.
D. Grötzsch, et al., Rev Sci Instrum. 88(12), 123112 (2017)
In situ gas cell for the analysis of adsorption behaviour on surfaces using X-ray spectroscopy
Abstract:
A gas cell for in-situ measurements of
Volatile Organic Compounds (VOCs) and their
adsorption behaviour on different surfaces by means of X-ray Fluorescence (XRF) and X-ray Absorption Fine-Structure (XAFS) spectroscopy has been developed. The cell is especially designed to allow for the efficient excitation and detection of low-Z elements such as carbon, oxygen or nitrogen as main components of VOCs. Two measurement modes are available. In the surface mode, adsorption on a surface can be studied using XAFS by fluorescence detection under shallow angles of incidence. The transmission mode enables the simultaneous investigation of gaseous samples via XAFS in transmittance and fluorescence detection modes. Proof-of-principle experiments were performed at the PTB plane grating monochromator beamline for soft X-ray radiation at the synchrotron radiation facility BESSY II. The flexible design and high versatility of the cell are demonstrated with the investigation of ethanol (EtOH) as one of the most abundant VOCs. The comparison of Near-Edge X-ray Absorption Fine-Structure (NEXAFS) spectra under transmission and fluorescence detection in the gas phase with measurements of adsorbed molecules on a Si-wafer surface both at the C and O-K absorption edges proves the applicability of the cell for the monitoring of adsorption processes.
Abstract:
For the investigation of spin crossover (SCO) complexes by XAS measurements in the tender to hard X-ray regime, a transmission heating cell has been developed. SCO complexes show a spin transition at certain temperatures above room temperature (RT). To measure a reliable hysteresis curve, high temperature stability (preferably < 0.5,°C) as well as minimal overheating of the setpoint temperatures (< 1 °C) has been achieved. The cell is designed for use in our von Hámos XAS laboratory spectrometer. The SCO complex [Fe(bzimpy)2](ClO4)2·0.25H2O was investigated as a first proof-of-principle experiment. In situ measurements up to 250 °C were carried out, showing the characteristic spin transition of the SCO complex during heating. Further XAS measurements were conducted at beamline BL10 of the DELTA storage ring, which demonstrated the feasibility of in situ measurements during a continuous temperature
ramp with our heating cell. The current temperature limit of the cell is 500 °C when used in vacuum. Hence, the cell can also be used for other sample systems, such as thermoelectric materials, which are frequently investigated in this temperature regime.
