ORIENTATION AND TEMPERATURE DEPENDENCE OF THE Cd K-SHELL EXAFS OF SINGLE CRYSTAL Cd METAL : FIRST EXAFS OBSERVATION OF R2

The K-shell X-ray absorpt ion spectrum of a Cd s i n g l e c r y s t a l has been measured a t temperatures from 4 t o 300K with the c rys t21 i n two or ien ta t ions one optimizing EXAFS from the f i r s t Cd d i s tance (R1 = 2.97A), t h e o t h e r optimizing EXAFS from the second Cd dis tance (R2 = 3.291). Clear evidence is obtained f o r R2 although i ts v i s i b i l i t y var ies g r e a t l y with temperature on account of t h e l a r g e anisotropy i n the thermal motion. The Debye-Waller f a c t o r s f o r the thermal motion along R1 and R2 a r e derived and compared t o theory.