35. A back-reflection Laue pattern of an aluminum crystal (fcc) with a = 4.05 Å is
obtained from (111) planes making an angle of 85° with the incident X-ray
beam. Assuming that the wavelengths above 2.5 Å are extremely weak and
they get absorbed in air. If the tube voltage is 60 kV, the maximum orders of
(111) reflection present is:
(a) 18
(b) 20
(c) 22
(d) 24
36. In a rotation photograph, three layer lines are observed both above and below
the zero layer line. A millimeter scale placed next to the developed film gives
the following readings:
Layer line
Height (mm)
Height w.r.t zero layer
3
05.40
34.00
2
22.44
16.96
1
31.84
07.56
0
39.40
–
−1
46.96
07.56
−2
56.35
16.95
−3
73.20
33.80
If the diameter of the camera is 57.3 mm and the wavelength of X-ray used is
1.542 Å, the value of the cell height is:
(a) 9.05 Å
(b) 8.05 Å
(c) 7.05 Å
(d) 6.05 Å
37. In a rotation photograph, first and second layer lines are observed (w.r.t zero
layer line) at 18 mm and 40 mm, respectively. If the wavelength of the MoKa
radiation is 0.71 Å and the film diameter 57.3 mm, the lattice parameter of the
sample is:
(a) 1.54 Å
(b) 2.54 Å
(c) 3.54 Å
(d) 4.54 Å
9.1 Steps in Crystal Structure Determinations
377