Laser Heating on Beamline I15 at Diamond

Laser Heating on Beamline I15 at Diamond
Dominik Daisenberger, Simone Anzellini, Annette Kleppe, Allan Ross,
Jon Thompson, Stuart Gurney, David Hawkins and Heribert Wilhelm
Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, U.K.
www.diamond.ac.uk/Beamlines/Engineering-and-Environment/I15
MAIN COMPONENTS OF THE EXTREME CONDITIONS BEAMLINE (I15)
BEAMLINE LAYOUT
• Insertion device: superconducting multi-pole wiggler
• Si(111) Bragg double-crystal monochromator: E = 20-80 keV
• Pair of 1 m long KB mirrors: minimum focal spot size ~70 μm
Station 1: 6-circle diffractometer
• Minimum (collimated) beam size 20 μm
• Powder and single-crystal diffraction, pair distribution function measurements
• High pressure (DAC), resistive heating, and low-temperature (T > 8 K) experiments
Station 2: X-ray micro-focusing and laser heating
• Pair of 30 cm long KB mirrors: minimum focal spot size ~8 μm
• Double sided YAG laser heating currently being commissioned
• DAC powder diffraction
Detectors:
MAR345, Perkin Elmer flat panel, Atlas CCD, Pilatus 100K
SCHEMATIC OF THE ON-LINE LASER HEATING SET-UP
DIAMOND ANVIL CELL LASER HEATING
• Double-sided (2 x 100 W) laser YAG heating (λ = 1090 nm) in onaxis configuration (see schematic to the right and photos below).
• Apochromatic objectives L1 focus the lasers onto the sample and
collect thermal emission spectra.
• Dichroic mirrors (DM) separate laser and visible light.
• L2 focuses the light onto spectrometer entrance (15x magnification).
• A mirror with two, vertically separated, pinholes provides the
spectrometer entrance pupils.
• A CCD camera records the sample image superimposed on the
entrance pupil (via beam splitter and Navitar Zoom objective). This
allows the spectrometer entrance pupil to be aligned to the laser and
X-ray beams.
• Thermal-emission spectra of up- and downstream sides of the sample
are recorded on different stripe of the spectrometer CCD.
• The sample temperature is obtained from a fit of Planck and Wien
functions to the emission spectra.
ON-LINE LASER HEATING SYSTEM AT BEAMLINE I15
L1
PH
TM
L1
TM
The sample stage of the on-line
laser heating system. The laser
beams are focussed and directed
onto the sample with lenses L1
and mirrors TM, respectively.
XRD Detector
Carbon fibre
strut
m-KBs
LED
Spectrometer
L2
DAC
HKHKHK
On-line laser heating system at I15. Photograph taken at roughly 45°
to the upstream X-ray beam direction, showing the breadboard
mounted on the station 2 table. The optical system is adjacent to the
micro-focussing KB-mirror vessel (left) and the X-ray detector. The
location of some components is indicated.
The entire optical system is mounted on a
motorised breadboard, attached to the table
of station 2. The breadboard can move
horizontally and vertically with respect to
the X-ray path. The objectives L1 and Xray transparent mirrors TM are attached to
the breadboard via a carbon fibre strut.
The entire optical system can therefore be
translated independently of the sample.
This simplifies the alignment of the optical
system to the sample which is centred to
the X-ray beam.
For remote control of laser heating
experiments objectives L1 are motorised
individually. In addition L1 and TM can
also travel back along the carbon fibre strut
towards the breadboard to facilitate change
of DACs on the sample stage.
Temperature information will be saved
together with the diffraction data in Nexus
data format.
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Acknowledgements: We thank M. Walter for fruitful discussions and Lee Hudson for technical
support. The laser-heating project is supported by NERC grant NE/M000117/1.