An easily constructed microwave Bragg diffraction apparatus is described, suitable for students in introductory physics classes. In contrast with previously published designs, only a single device, either the transmitter or the receiver, must be rotated in order to locate and unambiguously identify Bragg scattering maxima from several low-index crystal planes. Employing the “rotating crystal” technique, the orientation of the crystal need not be known a priori. This allows the students to use their measurements of to determine the lattice spacing and the orientation of a concealed crystal, thereby mimicking the procedures used in real x-ray crystallography.
REFERENCES
1.
Roland A.
Allen
, “Verification of Bragg’s Law by the use of microwaves
,” Am. J. Phys.
23
, 297
–298
(1955
).2.
Robert G.
Marcley
, “Apparatus drawings project #6: Bragg diffraction apparatus
,” Am. J. Phys.
28
, 415
–417
(1960
).3.
Thomas D.
Rossing
, Rodney
Stadum
, and Douglas
Lang
, “Bragg diffraction of microwaves
,” Am. J. Phys.
41
, 129
–130
(1973
).4.
T. G.
Bullen
, “An improved mounting for the Welch–Bragg diffraction apparatus
,” Am. J. Phys.
37
, 333
(1969
).5.
William Henry
Murray
, “Microwave diffraction techniques from macroscopic crystal models
,” Am. J. Phys.
42
, 137
–140
(1974
).6.
M. T.
Cornick
and S. B.
Field
, “Microwave Bragg diffraction in a model crystal lattice for the undergraduate laboratory
,” Am. J. Phys.
72
, 154
–158
(2004
).7.
Bailey L.
Donnally
, George
Bradley
, and Jacob
Dewitt
, “Models for microwave analogs of Bragg scattering
,” Am. J. Phys.
36
, 920
(1968
).8.
See EPAPS Document No. E-AJPIAS-77-011909 for a complete set of shop drawings. This document can be reached via a direct link in the online article's HTML reference section or via the EPAPS homepage (http://www.aip.org/pubservs/epaps.html).
© 2009 American Association of Physics Teachers.
2009
American Association of Physics Teachers
AAPT members receive access to the American Journal of Physics and The Physics Teacher as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.
