Difference between revisions of "GIWAXS"
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'''Grazing-Incidence Wide-Angle X-ray Scattering''' ('''GIWAXS''') is a structural measurement technique wherein wide-angle [[scattering]] is collected; i.e. large values of the [[momentum transfer]]. Because of the [[Fourier transform|inverse nature]] of [[reciprocal-space]], these large values of ''[[q]]'' [[Q value|correspond]] to small distances; [[WAXS]] generically probes molecular length-scales. It is thus the wide-angle analogue of [[GISAXS]]. | '''Grazing-Incidence Wide-Angle X-ray Scattering''' ('''GIWAXS''') is a structural measurement technique wherein wide-angle [[scattering]] is collected; i.e. large values of the [[momentum transfer]]. Because of the [[Fourier transform|inverse nature]] of [[reciprocal-space]], these large values of ''[[q]]'' [[Q value|correspond]] to small distances; [[WAXS]] generically probes molecular length-scales. It is thus the wide-angle analogue of [[GISAXS]]. | ||
| − | There is no unambiguous delineation between [[WAXS]] and [[SAXS]]; generally speaking, WAXS corresponds to angles from approximately 1° to 45°, or ''q''-values from 0.1 Å<sup>−1</sup> to 5 Å<sup>−1</sup> ([[realspace]] distances from 6 nm to Angstroms). | + | There is no [[Definitional_boundaries#Angle_ranges|unambiguous delineation]] between [[WAXS]] and [[SAXS]]; generally speaking, WAXS corresponds to angles from approximately 1° to 45°, or ''q''-values from 0.1 Å<sup>−1</sup> to 5 Å<sup>−1</sup> ([[realspace]] distances from 6 nm to Angstroms). |
==Example Data== | ==Example Data== | ||
Latest revision as of 11:08, 24 January 2015
Grazing-Incidence Wide-Angle X-ray Scattering (GIWAXS) is a structural measurement technique wherein wide-angle scattering is collected; i.e. large values of the momentum transfer. Because of the inverse nature of reciprocal-space, these large values of q correspond to small distances; WAXS generically probes molecular length-scales. It is thus the wide-angle analogue of GISAXS.
There is no unambiguous delineation between WAXS and SAXS; generally speaking, WAXS corresponds to angles from approximately 1° to 45°, or q-values from 0.1 Å−1 to 5 Å−1 (realspace distances from 6 nm to Angstroms).
Example Data
P3HT
Different representations of data from a P3HT thin film. The fairly broad rings are consistent with the small grain sizes (~20 nm) in this material. The P3HT lamellar-stacking peaks (100, 200, 300) are concentrated along the vertical, due to the preferentially 'edge-on' orientation of this material, with respect to the substrate.
 Data converted to q-space, taking into account the Ewald sphere (notice the 'missing wedge' near the qz axis). |
Tungsten-Nickel alloy
The many bright rings arise from the well-defined atomic [[unit cell]. The peaks appear at large q (a.k.a. large angle), because they arise from small (atomic) distance-scales. The peaks are sharp, indicative of large grains; in fact they appear somewhat speckled, indicative of a well-ordered material.
Rubrene
Notice the well-defined peaks through the WAXS. These diffraction peaks appear as spots (as opposed to rings) because the material is well-oriented with respect to the substrate. Instead of ordering in an isotropic manner, this sample has a very well-defined crystallographic orientation with respect to the substrate (because of epitaxial substrate growth).
