Refractive index - Revision history

KevinYager: /* See Also */

2019-04-16T12:49:01Z

‎See Also

KevinYager: /* See Also */

2019-03-21T20:27:40Z

‎See Also

KevinYager: /* Mathematical form */

2015-07-25T17:01:10Z

‎Mathematical form

KevinYager: /* Mathematical form */

2015-07-25T17:00:47Z

‎Mathematical form

KevinYager: /* Mathematical form */

2015-01-28T19:24:11Z

‎Mathematical form

KevinYager at 20:45, 14 October 2014

2014-10-14T20:45:19Z

KevinYager at 14:22, 16 June 2014

2014-06-16T14:22:30Z

KevinYager: /* Total external reflection */

2014-06-14T15:43:58Z

‎Total external reflection

66.249.83.102: /* Total external reflection */

2014-06-12T01:07:11Z

‎Total external reflection

KevinYager: /* See Also */

2014-06-06T18:38:50Z

‎See Also

← Older revision		Revision as of 12:49, 16 April 2019
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	* [[Scattering Length Density]]		* [[Scattering Length Density]]
	* [http://henke.lbl.gov/optical_constants/getdb2.html CXRO refractive index calculator]		* [http://henke.lbl.gov/optical_constants/getdb2.html CXRO refractive index calculator]
		+	* Liu, J.; Yager, K.G. [http://journals.iucr.org/m/issues/2018/06/00/hf5364/index.html Unwarping GISAXS data] ''IUCrJ'' '''2018''', 5, 737–752. [http://dx.doi.org/10.1107/S2052252518012058 doi: 10.1107/S2052252518012058]

← Older revision		Revision as of 20:27, 21 March 2019
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	* [[Critical angle]]		* [[Critical angle]]
	* [[Scattering Length Density]]		* [[Scattering Length Density]]
		+	* [http://henke.lbl.gov/optical_constants/getdb2.html CXRO refractive index calculator]

@@ Line 13: / Line 13: @@
 n = 1 - \delta + i \beta
 </math>
-The real and imaginary components, <math>\scriptstyle \alpha </math> and ''β'', describe the dispersive and absorptive aspects of the wave-matter interaction. These components can be calculated from the [[atomic scattering factors]] (''f''<sub>1</sub> and ''f''<sub>2</sub>) using:
+The real and imaginary components, <math>\scriptstyle \delta </math> and ''β'', describe the dispersive and absorptive aspects of the wave-matter interaction. These components can be calculated from the [[atomic scattering factors]] (''f''<sub>1</sub> and ''f''<sub>2</sub>) using:
 :<math>
 \delta = \frac{ n_a r_e \lambda^2 }{2 \pi} f_1

@@ Line 13: / Line 13: @@
 n = 1 - \delta + i \beta
 </math>
-The real and imaginary components, ''𝛿'' and ''β'', describe the dispersive and absorptive aspects of the wave-matter interaction. These components can be calculated from the [[atomic scattering factors]] (''f''<sub>1</sub> and ''f''<sub>2</sub>) using:
+The real and imaginary components, <math>\scriptstyle \alpha </math> and ''β'', describe the dispersive and absorptive aspects of the wave-matter interaction. These components can be calculated from the [[atomic scattering factors]] (''f''<sub>1</sub> and ''f''<sub>2</sub>) using:
 :<math>
 \delta = \frac{ n_a r_e \lambda^2 }{2 \pi} f_1

@@ Line 24: / Line 24: @@
 n_a = \frac{\rho N_a}{M_a}
 </math>
-where ''ρ'' is the physical density (e.g. in g/cm<sup>3</sup>), ''N<sub>a</sub>'' is the [http://en.wikipedia.org/wiki/Avogadro_constant Avogadro constant] (6.02214129x10<sup>23</sup> mol<sup>−1</sup>), and ''M<sub>a</sub>'' is molar mass (e.g. in g/mol). There are also [http://henke.lbl.gov/optical_constants/getdb2.html online tools] that will compute the refractive index for you.
+where ''ρ'' is the physical density (e.g. in g/cm<sup>3</sup>), ''N<sub>a</sub>'' is the [http://en.wikipedia.org/wiki/Avogadro_constant Avogadro constant] (6.02214129x10<sup>23</sup> mol<sup>−1</sup>), and ''M<sub>a</sub>'' is molar mass (e.g. in g/mol). There are also [http://henke.lbl.gov/optical_constants/getdb2.html online tools] that will compute the refractive index for you. The real part of the refractive index can also be directly related to the [[electron-density distribution|electron-density]]:
 ==Refraction==

← Older revision		Revision as of 20:45, 14 October 2014
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−	The '''refractive index''' for x-rays is strictly analogous to the conventional (visible light) refractive index. It describes how strongly wave propagation is altered within the given material. The modification of the wave's phase velocity in turn causes the propagation direction to be altered (i.e. the wave is refracted).	+	The '''refractive index''' for [[x-rays]] is strictly analogous to the conventional (visible light) refractive index. It describes how strongly wave propagation is altered within the given material. The modification of the wave's phase velocity in turn causes the propagation direction to be altered (i.e. the wave is refracted).

	==Total external reflection==		==Total external reflection==

@@ Line 4: / Line 4: @@
 X-rays interact rather weakly with matter (e.g. [[absorption lengths]] are on the order of millimeters); x-ray refractive indices are thus extremely close to 1. In fact, x-ray refractive indices tend to be slightly ''smaller'' than 1, giving rise to total ''external'' reflection at sufficiently small angle. This can be compared to total ''internal'' reflection typically observed for visible light.
-Visible light can be totally reflected when travelling from a denser medium into a less denser medium (e.g. light traveling in glass towards a glass-air interface will be totally reflected when the incident angle (measured from the interface) is less than ~50°). Whereas for x-rays, the beam can be totally reflected when travelling from a less dense medium into a denser medium (e.g. x-rays traveling in vacuum towards a [[Materal:Vacuum|vacuum]]-[[Material:Silicon|silicon]] interface will be totally reflected if the grazing-incidence angle is less than ~0.2°).
+Visible light can be totally reflected when travelling from a denser medium into a less denser medium (e.g. light traveling in glass towards a glass-air interface will be totally reflected when the incident angle (measured from the interface) is less than ~50°). Whereas for x-rays, the beam can be totally reflected when travelling from a less dense medium into a denser medium (e.g. x-rays traveling in vacuum towards a [[Material:Vacuum|vacuum]]-[[Material:Silicon|silicon]] interface will be totally reflected if the grazing-incidence angle is less than ~0.2°).
 Notice that because the refractive index is very close to 1, the [[critical angle]]s are very small (as measured from the interface). The critical angle depends on the x-ray energy and the material, but is typically on the order of 0.1° to 0.5°.

← Older revision		Revision as of 18:38, 6 June 2014
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	==See Also==		==See Also==
	* [[Critical angle]]		* [[Critical angle]]
		+	* [[Scattering Length Density]]