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that is general to scattering techniques. Finally, neutrons are highly penetrating and typically non-perturbing: which allows for great flexibility in sample environments, and the use of delicate sample materials (e.g., biological specimens). By contrast x-ray exposure may damage some materials, and
763:
Although other reflectivity techniques (in particular optical reflectivity, x-ray reflectometry) operate using the same general principles, neutron measurements are advantageous in a few significant ways. Most notably, since the technique probes nuclear contrast, rather than electron density, it is
504:
onto an extremely flat surface and measuring the intensity of reflected radiation as a function of angle or neutron wavelength. The exact shape of the reflectivity profile provides detailed information about the structure of the surface, including the thickness, density, and roughness of any thin
706:
Off-specular reflectometry gives rise to diffuse scattering and involves momentum transfer within the layer, and is used to determine lateral correlations within the layers, such as those arising from magnetic domains or in-plane correlated roughness.
780:, etc.). Sensitivity to isotopes also allows contrast to be greatly (and selectively) enhanced for some systems of interest using isotopic substitution, and multiple experiments that differ only by isotopic substitution can be used to resolve the
817:
upon exposure to the beam, and insensitivity to the chemical state of constituent atoms. Moreover, the relatively lower flux and higher background of the technique (when compared to x-ray reflectivity) limit the maximum value of
738:
techniques, neutron reflectometry is sensitive to contrast arising from different nuclei (as compared to electron density, which is measured in x-ray scattering). This allows the technique to differentiate between various
805:
is one optical method which provides analogous results to neutron reflectometry at comparable resolution although the underpinning mathematical model is somewhat simpler, i.e. it can only derive a thickness (or
650:
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843:
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429:
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589:-component. A typical neutron reflectometry plot displays the reflected intensity (relative to the incident beam) as a function of the scattering vector:
32:
251:
351:
461:. The technique provides valuable information over a wide variety of scientific and technological applications including chemical aggregation,
383:
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mode, where the angle of the incident beam is equal to the angle of the reflected beam. The reflection is usually described in terms of a
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Disadvantages of neutron reflectometry include the higher cost of the required infrastructure, the fact that some materials may become
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direction is defined to be the direction normal to the surface, and for specular reflection, the scattering vector has only a
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or the
Parratt recursion can be used to calculate the specular signal arising from the interface.
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The wavelength of the neutrons used for reflectivity are typically on the order of 0.2 to 1
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865:. Lecture Notes in Physics. Vol. 770. Berlin Heidelberg: Springer. p. 183.
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Neutron reflectometery emerged as a new field in the 1980s, after the discovery of
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more sensitive for measuring some elements, especially lighter elements (
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472:, structure of thin film magnetic systems, biological membranes, etc.
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793:). Also, optical techniques may include ambiguity due to optical
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density (SLD) and can be used to accurately calculate material
15:
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Catalogue of data analysis software at www.reflectometry.net
889:
Catalogue of neutron reflectometers at www.reflectometry.net
645:{\displaystyle q_{z}={\frac {4\pi }{\lambda }}\sin(\theta )}
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that can be probed (and hence the measurement resolution).
801:), which complementary neutron measurements can resolve.
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453:, similar to the often complementary techniques of
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861:Dalliant, Jean; Gibaud, Alain, eds. (2009).
759:Comparison to other reflectometry techniques
508:Neutron reflectometry is most often made in
48:introducing citations to additional sources
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449:technique for measuring the structure of
496:The technique involves shining a highly
38:Relevant discussion may be found on the
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789:light can modify some materials (e.g.
747:. Neutron reflectometry measures the
7:
755:if the atomic composition is known.
256:Fundamental research with neutrons:
14:
803:Dual polarisation interferometry
505:films layered on the substrate.
252:Prompt gamma activation analysis
122:
31:relies largely or entirely on a
20:
810:) for a uniform layer density.
699:is the angle of incidence. The
863:X-ray and Neutron Reflectivity
639:
633:
188:Small-angle neutron scattering
1:
718:). This technique requires a
488:-coupled multilayered films.
380:ISIS Neutron and Muon Source
205:Inelastic neutron scattering
220:Backscattering spectrometer
215:Time-of-flight spectrometer
925:
749:neutron scattering length
722:, which may be either a
668:{\displaystyle \lambda }
210:Triple-axis spectrometer
701:Abeles matrix formalism
692:{\displaystyle \theta }
482:giant magnetoresistance
272:Neutron capture therapy
59:"Neutron reflectometry"
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225:Spin-echo spectrometer
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838:{\displaystyle q_{z}}
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542:{\displaystyle q_{z}}
486:antiferromagnetically
443:Neutron reflectometry
822:
732:particle accelerator
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402:Under construction:
267:Fast neutron therapy
44:improve this article
730:source (based on a
510:specular reflection
447:neutron diffraction
248:Activation analysis
183:Neutron diffraction
139:Neutron temperature
909:Neutron scattering
835:
736:neutron scattering
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642:
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455:X-ray reflectivity
324:Neutron facilities
258:Ultracold neutrons
243:Neutron tomography
235:Other applications
174:Neutron scattering
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582:{\displaystyle z}
562:{\displaystyle z}
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300:Neutron moderator
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304:Neutron optics:
292:Research reactor
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288:Neutron sources
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883:External links
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720:neutron source
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280:Infrastructure
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262:Interferometry
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42:. Please help
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872:9783540885870
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808:birefringence
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782:phase problem
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198:Reflectometry
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157:Cross section
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114:Science with
112:
103:
92:
89:
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82:
78:
75:
71:
68:
64:
61: –
60:
56:
55:Find sources:
49:
45:
41:
35:
34:
33:single source
29:This article
27:
23:
18:
17:
862:
856:
812:
791:photoresists
762:
734:). Like all
709:
705:
654:
507:
495:
479:
459:ellipsometry
442:
441:
197:
100:October 2022
97:
87:
80:
73:
66:
54:
30:
815:radioactive
350:Australia:
310:Supermirror
131:Foundations
849:References
795:anisotropy
728:spallation
677:wavelength
522:, denoted
498:collimated
470:adsorption
467:surfactant
451:thin films
392:Historic:
332:America:
296:Spallation
165:Activation
161:Absorption
70:newspapers
714:(2 to 10
687:θ
663:λ
637:θ
631:
623:λ
619:π
492:Technique
315:Detection
306:Reflector
152:Transport
148:Radiation
40:talk page
903:Category
774:nitrogen
766:hydrogen
745:elements
741:isotopes
517:transfer
514:momentum
502:neutrons
500:beam of
366:Europe:
342:NIST CNR
116:neutrons
753:density
476:History
463:polymer
84:scholar
869:
778:oxygen
770:carbon
679:, and
655:where
520:vector
372:FRM II
368:BER II
362:HANARO
358:J-PARC
356:Asia:
338:LANSCE
193:GISANS
86:
79:
72:
65:
57:
787:laser
726:or a
445:is a
91:JSTOR
77:books
867:ISBN
465:and
457:and
398:HFBR
394:IPNS
388:SINQ
384:JINR
352:OPAL
334:HFIR
144:Flux
63:news
743:of
628:sin
484:in
404:ESS
376:ILL
346:SNS
46:by
905::
776:,
772:,
768:,
712:nm
396:,
386:,
382:,
378:,
374:,
370:,
360:,
340:,
336:,
308:,
298:,
294:,
290::
260:,
250:,
163:,
159:,
150:,
146:,
875:.
831:z
827:q
797:(
716:Å
640:)
634:(
616:4
610:=
605:z
601:q
577:z
557:z
535:z
531:q
431:e
424:t
417:v
344:-
102:)
98:(
88:·
81:·
74:·
67:·
50:.
36:.
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