 Diffraction patterns obtained with 1.54 Å synchrotron and Cu Ka radiations showed thirteen reflections in the range 1.5-20.0 ° 2-theta.With the National Institute of Standards and Technology's standard reference material silicon as an internal standard, the long spacing of silver behenate was accurately determined from the profile-fitted synchrotron diffraction peaks, with d001 = 58.380 (3) Å (5.8380(3) nm).This result was in agreement with that obtained from the Cu Ka pattern.