X-ray magnetic circular dichroism (XMCD) is a difference spectrum of two x-ray absorption spectra (XAS) taken in a magnetic field, one taken with left circularly polarized light, and one with right circularly polarized light. By closely analyzing the difference in the XMCD spectrum, information can be obtained on the magnetic properties of the atom, such as its spin and orbital magnetic moment.
In the case of transition metals such as iron, cobalt, and nickel, the absorption spectra for XMCD are usually measured at the L-edge. This corresponds to the process in the iron case: with iron, a 2p electron is excited to a 3d state by an x-ray of about 700 eV. Because the 3d electron states are the origin of the magnetic properties of the elements, the spectra contain information on the magnetic properties.
Famous quotes containing the words magnetic and/or circular:
“We are in great haste to construct a magnetic telegraph from Maine to Texas; but Maine and Texas, it may be, have nothing important to communicate.”
—Henry David Thoreau (1817–1862)
“If one doubts whether Grecian valor and patriotism are not a fiction of the poets, he may go to Athens and see still upon the walls of the temple of Minerva the circular marks made by the shields taken from the enemy in the Persian war, which were suspended there. We have not far to seek for living and unquestionable evidence. The very dust takes shape and confirms some story which we had read.”
—Henry David Thoreau (1817–1862)