X rays

X rays are short wavelength electromagnetic radiation of wavelength 10^-11 to 10^-8 m.  This is about the size of an atom.  We associate X rays mostly with taking shadow pictures of broken bones, but they are also of use to the archaeologist:

• Corrosion products can be worked out, indicating the conditions in which an artifact has been stored;

• The materials that were used;

• How the materials were put together;

• What pigments were used.

• Dating bones.

the technique for studying materials is called X-ray diffraction.  You have seen how light (and other waves) get diffracted as they pass through a narrow gap.  The maximum diffraction occurs when the gap is about 1 wavelength.  Below 1 wavelength diffraction does not occur.

In this case the atoms in the crystal lattice cause the X-rays to diffract.

The X-rays superpose to form regions of constructive interference which appear as dark bands on the photographic films.  Mathematical analysis allows the archeologist to determine what crystals are there.