This convenient tool allows the user to quickly convert between different units for describing diffraction data.
  • Wavelength: the is the wavelength (lambda) of the incident radiation. Although it is initialized to the wavelength associated with the current data set, it can be set to any physically meaningful value desired. Changing the wavelength in this window will not change it elsewhere in the program.
  • Q: This is the momentum transfer, in the units most often used by physicists:
    Q = 2 pi / D = (4 pi / lambda) sin (theta)
  • S: This is also the momentum transfer, in the units often used by crystallographers:
    S = Q / 2 pi = 1 / D = (2 / lambda) sin(theta)
  • D: This is the d-spacing associated with a particular momentum transfer (not necessarily a actual plane spacing in any crystal):
    D = (2 pi / Q) = 1 / S
  • Theta: this is the angle between the incident beam and the scattering plane, in degrees.
  • 2-Theta: this is the angle between the incident and outgoing rays, in degrees.