xrd and raman spectroscopy - physics.muni.czdorian/zelina_xrd_raman.pdf · xrd raman spectroscopy...
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XRDRaman spectroscopy
Conclusions
XRD and Raman spectroscopyF8900 Študentský seminár
Peter [email protected]
Department of Physical ElectronicsFaculty of ScienceMasaryk University
May 4th, 2011
Peter Zelina XRD and Raman spectroscopy
XRDRaman spectroscopy
Conclusions
Outline
1 XRDIntroductionPrinciple
2 Raman spectroscopyTheoryPrinciple
3 Conclusions
Peter Zelina XRD and Raman spectroscopy
XRDRaman spectroscopy
ConclusionsIntroductionPrinciple
What is XRD?
X-Ray Diffraction = X-rays diffracted on lattice of the matterconstructive interference (Braggs condition):
2d sin θ = nλ2 a√
h2+k2+l2 sin θ = λ
When do I use XRD?qualitative and quantitative analysis of crystalline sampledistinguish between mixture and compoundsize of particles (powder XRD, size < 100 nm)
Peter Zelina XRD and Raman spectroscopy
XRDRaman spectroscopy
ConclusionsIntroductionPrinciple
How mathematics works...
F (~Q) =∑
sfs(Q)
structure factor︷ ︸︸ ︷exp(−i ~Q ·~rs) (1)
~rs direct lattice vector, ~Q reciprocal lattice vector ⇒ condition forMiller indeces h, k, l ⇒ angle of incidence θ
α-Fe Fe3O4hkl 2θ[◦] hkl 2θ[◦]
110 52 111 21200 77 220 35211 100 311 41220 124 400 50310 161 511 67
440 74
LP#14a - α-Fe/Fe3O4: 44:56; 10 nm, 4 nm
Scherer formula:
τ =Kλ
β cos θ
β = FWHMK - shape factor
Peter Zelina XRD and Raman spectroscopy
XRDRaman spectroscopy
ConclusionsIntroductionPrinciple
...and physics
source of X-rays: synchrotron, bremsstrahlung(Mo, Cu, Co, Fe, Cr)λ ≈ 0.06 nm (Mo) – 0.23 nm (Cr)
detector: CCD, photopaper
MoO3 nanowires, www.nanotul.com
Peter Zelina XRD and Raman spectroscopy
XRDRaman spectroscopy
ConclusionsTheoryPrinciple
Raman spectroscopy - Basic theory
inelastic scattering of monochromatic lightexcitations to virtual energy statessource: laser (λ0) - near UV – near IR
∆ω = (1λ0− 1λ
) (2)
When do I need Ramanspectroscopy?
info about spectra of molecules,chemical bondssolids, liquids, samples in water,glassNON-destructive, quick,no preparations needed
Peter Zelina XRD and Raman spectroscopy
XRDRaman spectroscopy
ConclusionsTheoryPrinciple
Principle
light irradiates the samplescattered light is detectedwavelengths λ ≈ λ0 are filtered
Applicationsdrugs, explosives detectionlow energy phononscomplement to IR spectroscopy
Peter Zelina XRD and Raman spectroscopy
XRDRaman spectroscopy
Conclusions
To sum upWe use...
XRD if...the sample is (poly)crystalline!qualitative, quantitative analysisnanopowder - size of particles
Raman spectroscopy if...info about rotational, vibrationalspectra, chemical bonds,phonon and magnon excitationscomplement to IR spectroscopy
Method is useless if...
the sample is NOT crystallinevery small objects (≈ λ)similar lattice parameters
laser changes structure of thesample, heats itthe sample is metal or alloy
Thank you for your attention!
Peter Zelina XRD and Raman spectroscopy
XRDRaman spectroscopy
Conclusions
To sum upWe use...
XRD if...the sample is (poly)crystalline!qualitative, quantitative analysisnanopowder - size of particles
Raman spectroscopy if...info about rotational, vibrationalspectra, chemical bonds,phonon and magnon excitationscomplement to IR spectroscopy
Method is useless if...
the sample is NOT crystallinevery small objects (≈ λ)similar lattice parameters
laser changes structure of thesample, heats itthe sample is metal or alloy
Thank you for your attention!
Peter Zelina XRD and Raman spectroscopy