Experiment

The Experiment section describes the different types of experimental diffraction data that EasyDiffraction can process. This includes both constant-wavelength neutron diffraction (CWL), time-of-flight neutron diffraction (TOF), and single-crystal neutron diffraction (SC CWL).

EasyDiffraction supports CIF-based(()) data formats and can also handle measured data files** in standard formats.

CIF-based data description

The following examples demonstrate the CIF data blocks for different diffraction experiments supported in EasyDiffraction.

pd-neut-cwl

This example represents a constant-wavelength neutron powder diffraction experiment:

data_hrpt

_diffrn_radiation.probe                 neutron
_diffrn_radiation_wavelength.wavelength 1.494

_pd_calib.2theta_offset 0.6225(4)

_pd_instr.resolution_u  0.0834
_pd_instr.resolution_v -0.1168
_pd_instr.resolution_w  0.123
_pd_instr.resolution_x  0
_pd_instr.resolution_y  0.0797

_pd_instr.reflex_asymmetry_p1 0
_pd_instr.reflex_asymmetry_p2 0
_pd_instr.reflex_asymmetry_p3 0
_pd_instr.reflex_asymmetry_p4 0

loop_
_pd_phase_block.id
_pd_phase_block.scale
lbco 9.0976(3)

loop_
_pd_background.line_segment_X
_pd_background.line_segment_intensity
_pd_background.X_coordinate
 10  174.3  2theta
 20  159.8  2theta
 30  167.9  2theta
 50  166.1  2theta
 70  172.3  2theta
 90  171.1  2theta
110  172.4  2theta
130  182.5  2theta
150  173.0  2theta
165  171.1  2theta

loop_
_pd_meas.2theta_scan
_pd_meas.intensity_total
_pd_meas.intensity_total_su
 10.00  167  12.6
 10.05  157  12.5
 10.10  187  13.3
 10.15  197  14.0
 10.20  164  12.5
 10.25  171  13.0
...
164.60  153  20.7
164.65  173  30.1
164.70  187  27.9
164.75  175  38.2
164.80  168  30.9
164.85  109  41.2

pd-neut-tof

This example demonstrates a time-of-flight neutron powder diffraction experiment:

data_wish

_diffrn_radiation.probe neutron

_pd_instr.2theta_bank 152.827

_pd_instr.dtt1 20773.1(3)
_pd_instr.dtt2    -1.08308
_pd_instr.zero   -13.7(5)

_pd_instr.alpha0 -0.009(1)
_pd_instr.alpha1  0.109(2)
_pd_instr.beta0   0.00670(3)
_pd_instr.beta1   0.0100(3)
_pd_instr.sigma0  0
_pd_instr.sigma1  0
_pd_instr.sigma2 15.7(8)

loop_
_pd_phase_block.id
_pd_phase_block.scale
ncaf 1.093(5)

loop_
_pd_background.line_segment_X
_pd_background.line_segment_intensity
_pd_background.X_coordinate
  9162.3  465(38) time-of-flight
 11136.8  593(30) time-of-flight
 14906.5  546(18) time-of-flight
 17352.2  496(14) time-of-flight
 20179.5  452(10) time-of-flight
 22176.0  468(12) time-of-flight
 24644.7  380(6)  time-of-flight
 28257.2  378(4)  time-of-flight
 34034.4  328(4)  time-of-flight
 41214.6  323(3)  time-of-flight
 49830.9  273(3)  time-of-flight
 58204.9  260(4)  time-of-flight
 70186.9  262(5)  time-of-flight
 82103.2  268(5)  time-of-flight
102712.0  262(15) time-of-flight

loop_
_pd_meas.time_of_flight
_pd_meas.intensity_total
_pd_meas.intensity_total_su
  9001.0  616.523  124.564
  9006.8  578.769  123.141
  9012.6  574.184  120.507
  9018.5  507.739  111.300
  9024.3  404.672  101.616
  9030.1  469.244  107.991
...
103085.0  275.072   60.978
103151.4  214.187   55.675
103217.9  256.211   62.825
103284.4  323.872   73.082
103351.0  242.382   65.736
103417.6  277.666   73.837

sc-neut-cwl

This example represents a single-crystal neutron diffraction experiment:

data_heidi

_diffrn_radiation.probe                 neutron
_diffrn_radiation_wavelength.wavelength 0.793

_pd_calib.2theta_offset 0.6225(4)

_pd_instr.resolution_u  0.0834
_pd_instr.resolution_v -0.1168
_pd_instr.resolution_w  0.123
_pd_instr.resolution_x  0
_pd_instr.resolution_y  0.0797

_pd_instr.reflex_asymmetry_p1 0
_pd_instr.reflex_asymmetry_p2 0
_pd_instr.reflex_asymmetry_p3 0
_pd_instr.reflex_asymmetry_p4 0

loop_
_exptl_crystal.id
_exptl_crystal.scale
tbti 2.92(6)

loop_
_refln.index_h
_refln.index_k
_refln.index_l
_refln.intensity_meas
_refln.intensity_meas_su
 1  1  1   194.5677    2.3253
 2  2  0    22.6319    1.1233
 3  1  1    99.2917    2.5620
 2  2  2   219.2877    3.2522
...
16  8  8    29.3063   12.6552
17  7  7  1601.5154  628.8915
13 13  7  1176.0896  414.6018
19  5  1     0.8334   20.4207
15  9  9    10.9864    8.0650
12 12 10    14.4074   11.3800

Other supported data formats

If instrumental parameters are not available in a CIF file, EasyDiffraction allows importing measured data files in standard formats. These files are automatically converted into CIF format with default parameters, which can be later modified within the software.

Supported data file formats:

• .xye or .xys (3 columns, including standard deviations)
  • _pd_meas.2theta_scan,
  • _pd_meas.intensity_total,
  • _pd_meas.intensity_total_su.
• .xy (2 columns, no standard deviations):
  • _pd_meas.2theta_scan,
  • _pd_meas.intensity_total.

If no standard deviations are provided, they are automatically calculated as the square root of measured intensities.

Optional comments with # are possible in data file headers.

Here are some examples:

example1.xye

# 2theta  intensity    su
   10.00     167      12.6
   10.05     157      12.5
   10.10     187      13.3
   10.15     197      14.0
   10.20     164      12.5
  ...
  164.65     173      30.1
  164.70     187      27.9
  164.75     175      38.2
  164.80     168      30.9
  164.85     109      41.2

example2.xy

# 2theta  intensity
   10.00     167    
   10.05     157    
   10.10     187    
   10.15     197    
   10.20     164    
  ...
  164.65     173    
  164.70     187    
  164.75     175    
  164.80     168    
  164.85     109  

example3.xy

10  167.3    
10.05  157.4    
10.1  187.1    
10.15  197.8    
10.2  164.9    
...
164.65  173.3    
164.7  187.5    
164.75  175.8    
164.8  168.1    
164.85  109     

Now that the Experiment has been defined, you can proceed to the next step: Analysis.