3. Different principles
(1) Energy absorption
E1 and E2 are different states of a molecule:
Vibrational states -> IR spectroscopy
Nuclear spin states -> NMR spectroscopy
electronic states -> UV/VIS spectroscopy
9. Why 2 ϴ ?
The Bragg diffraction condition contains only one
factor of θ: 2dsinθ=nλ
It should be noted that θ refers to the incidence angle
of the x-ray beam, and the beam is actually deflected
by an angle of 2θ, as illustrated in the image below:
27. What is the unit cell dimension a of NaCl ?
Use plane 111 with 2x theta = 27 deg
and λ = 1.54 nm (Cu-Kα)
28. Which plane will give a signal at
2x theta = 46 deg when the cubic constant
a = 0.5 nm and λ = 1.54 nm ?
29. X-rays with wavelength 1.54 Å are “reflected” from the
(1 1 0) planes of a cubic crystal with unit cell a = 6 Å.
Calculate the Bragg angle, ϴ, for orders of reflection, n =
1-5.
30. Use Braggs Law to calculate possible values for ϴ :
Solution:
44. Indices for HCP structures
http://www.materials.ac.uk/elearning/matter
/crystallography/indexingdirectionsandplanes
/indexing-of-hexagonal-systems.html
50. Reduced GO: 2θ = 26.29 degree
With λ = 0.154 nm the distance between the planes:
The close d-spacing of RGO to pristine graphite and
disappearance of peak at 2θ = 12.43 degree indicate
that the oxygen containing group of graphite oxide
have been efficiently removed
51. From: Nanomaterials 2015, 5, 826-834
Graphene Oxide Synthesis from Agro Waste
The peak at 2θ = 11.6° indicates an interlayer distance
of 0.79 nm fully oxidized graphite sheets
53. In the IR spectrum typical peaks of functional groups
can be identified:
Around 3500 cm-1: O-H stretching
1700 cm-1: typical for C=O stretching
1600 cm-1: C-C vibrations of graphite
1210 cm-1: C-OH stretching
54. From: Chem. Commun., 2011,47, 12370-12372
One-pot reduction of graphene oxide at subzero
temperatures
55. From: J. Chil. Chem. Soc. vol.58 no.4 Concepción dic. 2013
http://dx.doi.org/10.4067/S0717-97072013000400067
GREEN SYNTHESIS AND CHARACTERIZATION OF
GRAPHITE OXIDE BY ORTHOGONAL EXPERIMENT
Different
oxidation
parameters for
graphite