Convert from angstrom to X unit

Unit Definition (angstrom)
The Angstrom is a metric unit of length, equal to 0.1 nanometer or 10e-10 meter. Angstroms are most often used to measure the wavelength of light and are commonly used by chemists and physicists in the field of spectroscopy. One of the pioneers of spectroscopy was the Swedish physicist Anders Jon Ångström (1814-1874), after whom the unit is named.

Unit Definition (X unit)
The X-unit (symbol xu) is a unit of length formerly used to measure the wavelength of X-rays and gamma rays. The X-unit is approximately 1.0021×10-13 metre. Defined by the Swedish physicist Karl Manne Georg Siegbahn (1886-1978) in 1925, the X-unit could not at that time be measured directly; the definition was instead made in terms of the spacing between planes of the calcite crystals used in the measuring apparatus.