Low-energy electron-diffraction determination of the structure of successively deposited ordered layers of Cd on Ti(0001). I. The first layer

The successive stages of the deposition of Cd onto a clean Ti(0001) surface are studied by Auger electron spectroscopy (AES) and low-energy electron diffraction (LEED). Completion of successive layers of Cd up to the fourth is recognized by study of the AES and LEED spectra as a function of exposure. The atomic arrangement in the first layer is determined by the methods of LEED crystallography. The Cd atoms are not located in the hexagonal-close-packed positions that would be occupied by Ti atoms if the substrate were to grow, but are rather located in the face-centered-cubic positions with respect to the first two substrate layers. The distance between the Cd overlayer and the top Ti layer is 2.57 {}---somewhat more than the interlayer spacing in bulk Ti (2.34 {}) but less than the same in bulk Cd (2.81 {}) corresponding to a bond length of Cd to Ti of 3.08 {}.