Transcript No Slide Title

Using the latest powder diffraction
methods and software to solve the
problems of the world - can the Earth’s
outer core contain Oxygen?
L. M. D. Cranswick,
CCP14 (Collaborative Computation Project No 14 for
Single Crystal and Powder Diffraction)
Department of Crystallography;
Birkbeck College, University of London,
Malet Street, Bloomsbury, London, WC1E 7HX, UK.
E-mail: [email protected]
WWW: http://www.ccp14.ac.uk
Talk Aims
• Mention the advantages of using Energy Dispersive
diffraction
• Though emphasize that without good and appropriate
software analysis tools - you might end up with a pile
of Energy Dispersive diffraction data that is too
problematic to analyze effectively.
• Show that what might be considered superficial
software modifications can make a major impact to
assist in solving intractable problems (such as this
example).
• Minor rant about Synchrotron Hardware Fixation
Syndrome (SHFS)
Slide 2
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Notes Free Zone - they are on the web
http://www.ccp14.ac.uk/poster-talks/csiro2002/
Slide 3
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Is there Oxygen in the Earth’s outer core
• Why Bother?
•
Project headed by Professor Dave
Walker of the Lamont-Doherty
Earth Observatory of Columbia
University, New York, USA
•
Use energy dispersive X-ray
diffraction; and high pressure / high
temperature phase transitions to
help determine the volume of
Oxygen at high pressure and
temperature (~550°C and 2 to 9
GPa). Then see if the volume this
has interesting implications for
Oxygen being involved in the
Earth’s Outer Core
Slide 4
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
What do we need from the data?
Accurate Unit Cell volumes to
obtain the “equations of state”
of the phases of interest (how
the volume of the phases
change with pressure and
temperature)
T - RbClO4 = B2-RbCl + 2O2
4 R-KClO3 = 3 O-KClO4 + B2-KCl
O-KClO4 = B2-KCl + 2 O2
O2 from the differences in the
unit cell volumes
Thus use powder diffraction
Slide 5
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
What do we need from the diffraction
experiment
•Ability to penetrate high a “large volume” high pressure cell - high
temperature cell (in this case a multi-anvil Walker Cell)
•Ability to get the X-ray beam in and out of tight spaces
•Thus Energy Dispersive Diffraction can be advantageous for these
types of problems.
Slide 6
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Energy Dispersive Diffraction
E(keV) = 6.199 / (d_space * sin(theta_angle of Energy Dispersive detector))
• Angular Dispersive Diffraction (simplification)
– Roughly single X-ray wavelength (e.g., Cu k-alpha = 1.54180Å)
– detector collects in 2-theta - measuring intensities of single wavelength (single
energy) “diffracted” X-rays as a function of angle (2-theta)
• Bragg-Bretano / Debye Scherrer, etc laboratory systems (and neutron synchrotron)
• Energy Dispersive Diffraction
– want intense, high-energy / multi-energy (multi-wavelength) “white” X-ray
beam
– Energy sensitive detector at a “fixed angle” detects multi-energy (multiwavelength) “diffracted” X-rays as a function of energy (in KeV)
– analogous to Time of Flight neutron diffraction (TOF)
Slide 7
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Energy Dispersive Diffraction
Schematic Diagram
Collimator and
EDX detector – at a
fixed angle
(stationary)
White X_ray
Beam
Sample
Environment
Slide 8
Diffraction patterns are
obtained only of the
volume subtended by the
collimator with the
incident X-ray beam
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Energy Dispersive Diffraction : Advantages
• Can see “inside” unconventional sample environments
– Within limits: can have steel or other materials shielding the sample at
pressure and/or temperature
• thus samples can also be immersed in gas or liquid (hydrothermal synthesis)
• in-situ studies - reactions / explosions / properties under stress. Particle
flows within gases and fluids. Reactions in gas/fluid flow lines.
• Only see diffraction in the volume (nick-named the “lozenge”) defined
where the detector collimator subtends onto the incident white X-ray beam
• Spatial Resolution inside the sample environment
– Can narrow down the beam and collimator - and move the sample : thus
obtaining diffraction patterns from different spatial volumes inside the
sample environment
• Fast data collection times
– minutes to fractions of a second
Slide 9
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Energy Dispersive Diffraction
Schematic of following reactions inside reaction vessels
EDX
Detector
White X_ray
Beam
Sample
Environment
(e.g., hydrothermal cell,
non-ambient cell)
Slide 10
By moving the
sample stage, the
“lozenge” can see
(possibly transient)
reactant products at
different times after
mixing.
And/or the orientation
of particles under
flow – e.g., clays
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Energy Dispersive Diffraction
Beamline 16.4 at Daresbury X-ray Synchrotron, Cheshire, UK
• In high pressure mode and
Walker Cell and Press
installed
• All the hardware can make
for a crowded and
complicated environment.
Slide 11
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Energy Dispersive Diffraction :
Example of High pressure/temp. sample assembly for the multi-anvil Walker Cell
Slide 12
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Energy Dispersive Diffraction :
Example datasets at high pressure and high temperature
Slide 13
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
What do we need from the data to help us
determined if there can be Oxygen in the
Earth’s outer core?
• What do we want?
– “Accurate” Unit-cell volumes to obtain equations of state (EOS)
• When to we want it?
– Now!! (not 6 months to 5 years later!)
– (far better if synchrotron beamlines offer analysis software so that
problems can be defined and analysis performed in near real time)
• Collecting small to large amounts of diffraction data with the
intention of analysing it later is a effective way of getting low
productivity out of synchrotron and neutron sources.
Slide 14
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Synchrotron Hardware Fixation Syndrome
(SHFS)
• Diagnosis:
– A neurotic spending of all effort on custom novel synchrotron
hardware without consideration and similar effort put into
software analysis requirements
• Effects:
– Beamlines can have very low productivity due to data analysis being
unnecessarily problematic and taking months or years of analysis
(kludging together a software solution)
• Possible Cure:
– Make sure equal amounts of effort are spent on i) hardware, ii) data
collection and iii) analysis software
Slide 15
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
How can you detect if the beamline you are
using suffers from SHFS
• If you cannot do (at the minimum), preliminary analysis of the
data, it is very likely that the beamline suffers from
Synchrotron Hardware Fixation Syndrome. You would want
the option and ability to perform the entire data analysis in near
real time.
• Not having an “integrated” analysis system at the beamline not
only means wasting large amounts of users’ time; but that
problems may only be found well after the experiment when it
is too late to rectify them. (calibration problems, wrong sample
inserted, flaws in experimental design, interesting occurrences
that should have been immediately followed up)
Slide 16
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Thus the next problem :
Software Analysis:
Difficulties that need to be considered:
• Energy Dispersive Diffraction setup and calibration can be
very ad-hoc and problematic
• Possible Detector instability over short time spans
• Possible “other” detector problems
• (more neurotic of these problems only obvious when doing
whole pattern Le Bail fitting)
Slide 17
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Other Problems that need to be considered
• Poor resolution data with multiple sources of
spurious peaks
• Phase transitions give unknown cells
• Track how diffraction patterns are changing through
the experiments
Slide 18
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
3 x Problems that need to be overcome
(No Struggle - No Joy!)
• Overlapping multi-phase
powder patterns
• Large amounts of raw
diffraction data! (collecting
3 patterns each 5 to 300 seconds)
• Intensities are near
meaningless
–
–
–
–
no incident intensity spectrum
particle statistics problems
preferred orientation problems
X-ray absorption
Slide 19
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Software to help Analyse the Data:
XFIT, Crysfire, Chekcell and Rietica
•
•
•
•
XFIT peak profiling software
Crysfire powder indexing suite
Chekcell powder indexing tool
Rietica Rietveld for mass Le Bail fitting to
obtaining cell volumes and follow reactions
Slide 20
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Background to XFIT by Cheary and Coelho
• XFIT - peak profiling software for Windows
– http://www.ccp14.ac.uk/tutorial/xfit-95/
– 3 peak profiling options
• Fundamental parameters (only applicable in XFIT for Bragg-Bretano)
• Pearson-7 (for assymmetric peaks)
• Pseudo-Voight (for symmetric peaks)
– No hard limits on number of peaks that can be simultaeously
profiled (except memory and time)
– Can open over 100 XRD patterns for simultaneous display and peak
fitting
Slide 21
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Peak Profiling - XFIT
Examples of XFIT in action:
Slide 22
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Background to Crysfire by Robin Shirley
• Crysfire - powder indexing suite
– http://www.ccp14.ac.uk/tutorial/crys/
– Links to 8 different indexing programs
• ito, dicvol, treor, taup, lzon, fjzn, kohl and losh
– Simple DOS based menu system to run each
program
– All results are collated into a single summary file
• One line per solution
• Summary file can be used by Chekcell
Slide 23
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Powder Indexing - the “Crysfire” suite
Example of CRYSFIRE Screen prompting the saving into one of 8 different
indexing program formats:
Slide 24
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Chekcell - Jean Laugier and Bernard Bochu
http://www.ccp14.ac.uk/tutorial/lmgp/
•
•
•
•
•
Graphical Interpretation of powder indexing results
Full Windows Graphical User Interface (GUI)
Automatic Cell searching and spacegroup assignment
Sorting lists of trial cells based on several criteria
Reads the following raw powder diffraction file formats:
– Bruker RAW, Philips RD, RIET7 and CPI
• Reads the following peak files:
– Bruker DIF, Philip DI, XFIT TXT, Winfit DAT, Column format, Crysfire CDT
• Reads Crysfire Summary SUM files. As well as Crysfire summary files produced for
the individual indexing programs:
– dicvol, ito, treor, taup, lzon, fjzn, kohl
• Incorporates Ton Spek and A. Meetsma’s Le Page *** (an addition that can really
count) sub-cell / super-cell searching
• GUI Cell transformation
• New: Density / Z / Molecular Volume explorer
Slide 25
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Routine operation of Chekcell (1 of 5)
Open a data file
(optional if you only have
a peak listing)
Slide 26
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Routine operation of Chekcell (2 of 5)
Open the peak listing
(In this case generated by
the XFIT program)
Slide 27
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Routine operation of Chekcell (3 of 5)
Import the Crysfire
summary file listing of
found trial cells.
Slide 28
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Routine operation of Chekcell (4 of 5)
Play with the list of trial
cells and spacegroups and
hopefully obtain a good
cell that is also the “true”
cell.
Slide 29
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Routine operation of Chekcell (5 of 5)
•Automatic Cell and
Spacegroup searching
– can trudge through a
single selected
unitcell; or over
1000s of trial cells
looking for the best
cell and spacegroup
combination based
on parsimony of
extra reflections
criteria.
Slide 30
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Chekcell: Major new feature of Chekcell
Porting and “integration” of Ton Spek and A.
Meetsma’s Le Page
•Obtaining the Reduced Cell
– which many powder indexing programs
to not reliably determined
– Refer: "'Reduced Cells', M.J. Buerger,
(Zeitschift fur Kristallographie, BD
109, S. 42-60 (1957)”
•Efficient Sub-cell and super-cell
searching, then easy reviewing of
newly derived cells within the
Chekcell interface
Slide 31
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Chekcell: GUI Cell transformation
•Easily transform cells and test them withing Chekcell
•Knows about common transformations
•Can manually look at sub-cells and super-cells
Slide 32
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Chekcell: Density / Z / Molecular Volume Explorer
•Easily look at effects of Z, Density and molecular volume
Slide 33
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Chekcell: result of using Le Page
An example:
•Orthorhombic cell with
good FOM (Figure of
Merit)
•Le Page combined with
automatic “Best Solution”
easily finds a better
hexagonal cell based on
parsimony of extra
reflections criteria
Slide 34
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
1. Chekcell: indexing unknown cells from unexpected
phase transitions in high pressure experiments
• While quality of Energy
Dispersive diffraction data
is low: indexing is doable
thanks to Crysfire and
Chekcell.
• Due to LePage, can have
more confidence in finding
a good cell; and checking
for other sub-cells and
super-cells.
• In this screen image, a
new monoclinic cell
has been found
Slide 35
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
2. Chekcell: re-indexing lost cells (maybe transformed)
from big pressure jumps in high pressure experiments
due to racing a synchrotron beam-dump.
• Can also use “expected
volumes” as a guide in
refinding cells.
• Re-found a monoclinic
cell despite I/I20 = 19
(19 out of the 20 first
peaks were indexed)
Slide 36
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
3. Chekcell: re-index again (big jumps due to trying to
beat a synchrotron beam dump)
• Again, re-found a
monoclinic cell
despite I/I20 = 16!
(only 16 out of the first
20 peaks were indexed)
• (With 23 starting peaks)
Slide 37
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
XFIT / Chekcell / LePage Summary:
•These programs give you the
maximum chance of indexing
unknown unit-cells from powder
diffraction data, even of low data
quality.
Slide 38
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Background to Rietica by Brett Hunter
• Rietica Rietveld - Rietveld software
– http://www.rietica.org/
– Newish: Easy to use mass Le Bail fitting of angular and energy
dispersive data
– All files are ASCII Files
– Handles alpha 1 /alpha 2 (if relevant)
– Flexible : can manually edit Le Bail HKL files
Slide 39
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Rietica Rietveld for Mass Le Bail fitting to get cell volumes
Example of 3 phase setup : KClO3; KClO4, B2-KCl
• Easy to use and setup via GUI
• Le Bail is Structureless whole
profile fitting - just need cell
and spacegroup
• Easy to add and delete
structures
• All files are ASCII files (Data,
HKL and input file) which can
edited manually if required or
convenient
• Auto-marquardt damping for
initial unstable refinement if
required
• Impurities can be very obvious
when Le Bail fitting
Slide 40
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Rietica Rietveld for Mass Le Bail fitting :
Rietica Database of Structures
• Can store structures and Le
Bail derived unit cells at
various pressures for later
retrieval
• Add to the database at the click
of a button
• Select from Database option
with the Phase dialog box.
• When having 100s to 1000s of
datasets, ease and speed are
very important.
Slide 41
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Rietica Rietveld for Mass Le Bail fitting
At simplest: 3 step process after initial setup has been done
• Some beamlines give the option
of converting into 2-theta space
or refining native in KeV
• (2-theta can be convenient for
using search match and related
software)
• Le Bailing Sequence:
1. Copy over INP and HKL file
(using windows explorer)
2. Perform whole profile LB fit
3. Access / plot results - (check
need to add or delete phases)
4. Repeat above
Slide 42
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Rietica Rietveld for Mass Le Bail fitting
1 of 10
• Before the phase
transition
Slide 43
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Rietica Rietveld for Mass Le Bail fitting
2 of 10
• In the phase
transition
• No completely
freestanding peak
for KCl
Slide 44
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Rietica Rietveld for Mass Le Bail fitting
3 of 10
• Repeat as
required
• No completely
freestanding peak
for KCl
Slide 45
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Rietica Rietveld for Mass Le Bail fitting
4 of 10
• Repeat as
required
• No completely
freestanding peak
for KCl
Slide 46
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Rietica Rietveld for Mass Le Bail fitting
5 of 10
• Repeat as
required
• Still no
completely
freestanding peak
for KCl
Slide 47
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Rietica Rietveld for Mass Le Bail fitting
6 of 10
• Repeat as
required
Slide 48
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Rietica Rietveld for Mass Le Bail fitting
7 of 10
• Repeat as
required
Slide 49
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Rietica Rietveld for Mass Le Bail fitting
8 of 10
• Repeat as
required
Slide 50
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Rietica Rietveld for Mass Le Bail fitting
9 of 10
• Repeat as
required
Slide 51
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Rietica Rietveld for Mass Le Bail fitting
10 of 10
• Done!!!
Slide 52
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Rietica Rietveld for Mass Le Bail : Graphing up the results
Using Le Bail fitting
Slide 53
Using Traditional Methods
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Rietica Macro Language - RIET BASIC
• In theory, mass Le
Bailing of the easy
parts of a
temperature /
pressure run can be
done in a fully
automatic mode
• On present set of
EDX data, have
found it is best to
not refine too
quickly and instead
continually check
individual results
and Le Bail fits.
Slide 54
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
1. Rietica and Le Bailing : problems with stability and
calibration of the Energy Dispersive Detector(?)
• NaCl / Halite at Room
Temperature and
Pressure (thus is not
crystal strain)
• Very nasty miss-fits on
peak positions
• Possible instability in the
detector
• Peaks cause detector to
become unstable in the
region of high counts(?)
• Other problems?
Slide 55
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
2. Rietica and Le Bailing : problems with stability and
calibration of the Energy Dispersive Detector(?)
Le Bail fitting
Traditional Unitcell refinement
Non-unit weighting of reflections
Unit weighting of reflections
Isotherm data of different temperatures colliding
Inappropriate to use Le Bail fitting on this data
Though Le Bail can detect these problems on the
beam-line!!
Slide 56
(over a wide KeV range - the data is “on average”
linear)
Isotherm data no longer overlapping
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Using XFIT and UNITCELL for traditional Unit-cell
refinement and EOS to obtained unit weighting of HKLs
http://www.esc.cam.ac.uk/astaff/holland/
Slide 57
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Using XFIT and UNITCELL for EOS of NaCl and KCl :
But:Rietica can make sure the correct HKLs are assigned to the correct peaks
and phases - greater than 5 phases (spurious peaks can be easily identified)
Slide 58
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Volume of Oxygen as a function of Pressure
• Energy Dispersive XRD: vol
O2 ~10 cc/mol
• Established vol O2 from
shockwave experiments: ~15
cc/mol (50% difference)
• Reasons for differences in
Shockwave / Molecular
Dynamics / Impulsively
Stimulated Scattering
Measurements (~15 cc/mol)
vs Energy Dispersive Data
(~10 cc/mol) beyond the
scope of this talk
Slide 59
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
•
Chekcell and Rietica: results of the volume of Oxygen
and the earth’s other core
15 cc/mol means there cannot be
Oxygen (shockwave / molecular
dynamics)
• 10 cc/mol (EDX result) means there
can be Oxygen in the Earth’s outer
core and has implications :
– including the possibility of sensible
transport mechanisms between the
core mantle boundary
Slide 60
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk
Summary
• Hopefully show the potential power of energy dispersive diffraction
• And also the necessity of considering using the appropriate data
analysis software to be just has important as the diffraction hardware
• Perhaps also the horror of SHFS (Synchrotron Hardware Fixation
Syndrome)
• These programs (and many more) are also mirrored at the EPSRC funded
CCP14 project website:
http://www.ccp14.ac.uk
• Thanks:
–
–
–
–
–
–
Bob Cheary and Alan Coelho - XFIT
Robin Shirley - Crysfire
Jean Laugier and Bernard Bochu - Chekcell
Brett Hunter - Rietica Rietveld
Simon Redfern and Tony Holland - UNITCELL
Dave Walker, et al - Geosciences example
Slide 61
Using diffraction methods to solve the problems of the world
Lachlan M. D. Cranswick ([email protected]) http://www.ccp14.ac.uk