What are the key ingredients for a successful laser heating experiment at the synchrotron? Guoyin Shen CARS, University of Chicago GeoSoilEnviroCARS The University of Chicago Laser heating workshop, March 20, 2004

Some types of laser heating experiments * Overcome kinetic barrier * Stress release * In situ phase identification at high P-T * Phase relations (melting) * P-V-T equations of state * Phonons * Electrons * Magnetism GeoSoilEnviroCARS The University of Chicago Laser heating workshop, March 20, 2004

GeoSoilEnviroCARS The University of Chicago Laser heating workshop, March 20, 2004 DAC On-line detection Science LaserX-ray Data evaluation Sample Off-line detection

GeoSoilEnviroCARS The University of Chicago Laser heating workshop, March 20, 2004 Diamond Anvil Cell - Allow double sided heating - Have large access opening - Gasket (thickness, energy) - Cooling (stability) Gasket 22 WC seat Diamond anvil X-ray transparent seat

GeoSoilEnviroCARS The University of Chicago Laser heating workshop, March 20, 2004 Laser heating system Type (YLF, CO 2 ) Power distribution (modes) Heating spot size Stability (short and long term) Pointing stability (laser, optics) Feed back system Temperature measurement system User “friendly”

X-ray beam Energy Size Cleanliness “Visibility” GeoSoilEnviroCARS The University of Chicago Laser heating workshop, March 20, 2004 X-ray (5-7  m) <10  m beam Sample (>20  m) Detection

GeoSoilEnviroCARS The University of Chicago Laser heating workshop, March 20, 2004 Alignment Five path alignment (2+2+1) With coaxial optics, three path alignment (1+1+1) X-ray position (visual image, small marker) No pre-alignment, every cell is unique Alignment stability (< 2  m)

Sample environment Absorption considerations Self absorption (metal, semi-transparent) Mixture Double hot plates Insulation considerations (medium) Materials (Ar, NaCl, Al 2 O 3, MgO, KCl…) Thickness Diffraction pattern, absorption,... Sample Grain size, thickness, shape (disc) Others Pressure determination X-ray alignment Loading environment GeoSoilEnviroCARS The University of Chicago Laser heating workshop, March 20, 2004 sampleGasket laser medium X-ray

GeoSoilEnviroCARS The University of Chicago Laser heating workshop, March 20, 2004 Detection - Atomic structure diffraction, EXAFS,… - Phonons nuclear inelastic scattering, … - Electronic structure x-ray Raman, emission, absorption - Magnetism Mössbauer, emission - Chemical composition emission, absorption, … ……

GeoSoilEnviroCARS The University of Chicago Laser heating workshop, March 20, 2004 Data evaluation * Large amount of data notes (data catcher), software * “Unexpected” features conditions, chemistry, reproducibility * “Dynamic” experiments on-line analysis