Introduction:
X-rays are a form of electromagnetic radiation with short wavelengths and high energies. They have the ability to penetrate materials and are widely used in medical imaging and scientific research. When X-rays encounter a regular pattern of atoms, such as in a crystal lattice, they can undergo a process called diffraction.

Explanation:
1. Diffraction:
Diffraction is the bending or spreading of waves as they pass through an opening or around an obstacle. It occurs when a wave encounters an obstruction that is comparable in size to its wavelength. The phenomenon of diffraction is commonly observed with light waves, where it can be demonstrated using a diffraction grating.

2. Diffraction Grating:
A diffraction grating is a device that consists of a large number of parallel slits or lines separated by equal distances. When light passes through a diffraction grating, it is diffracted into multiple beams that interfere constructively or destructively, producing a pattern of bright and dark regions.

3. X-ray Diffraction:
X-ray diffraction is a technique used to study the atomic and molecular structure of materials. When X-rays pass through a crystal lattice, they interact with the electrons in the atoms, causing them to scatter. The scattered X-rays interfere with each other, producing a diffraction pattern that can be analyzed to determine the arrangement of the atoms in the crystal.

4. X-ray Diffraction and Gratings:
While diffraction gratings are commonly used to study the diffraction of light waves, they are not suitable for diffracting X-rays. This is mainly due to the short wavelength of X-rays. X-rays have much shorter wavelengths compared to visible light, ranging from 0.01 to 10 nanometers.

5. Limitations of Gratings:
Gratings are designed to diffract light waves with wavelengths on the order of hundreds of nanometers. When X-rays with wavelengths in the nanometer range encounter the slits or lines of a diffraction grating, they do not interact with the grating structure in a significant way. The spacing between the slits or lines of a grating is much larger than the wavelength of X-rays, so the X-rays pass through the grating without significant diffraction.

Conclusion:
In conclusion, X-rays cannot be diffracted by means of an ordinary grating because the spacing between the slits or lines of a grating is much larger than the wavelength of X-rays. X-rays have short wavelengths, and their interaction with matter is mainly through scattering rather than diffraction. X-ray diffraction techniques require specialized methods and instruments, such as crystallography or Bragg's law, to analyze the diffraction patterns produced by X-rays.