Accurate Determination of Hydrogen Positions in NH₄Cl by Electron Diffraction

Abstract

The hydrogen position in NH₄Cl was determined by the difference Fourier syntheses from the electron diffraction Debye-Scherrer ring intensity data at a room temperature and a low temperature (−40°C). The primary extinction effect for strong reflections such as (110) plane was corrected from the variation of their intensities by changing the accelerating voltages between 20 and 60 kv. By the use of the least square method, the temperature factors were determined from higher order reflections whose atomic scattering factors are not affected by ionization.
The difference Fourier syntheses showed the coordinate (xxx) of the hydrogen atoms to be x=0.153 for both the room temperature and the low temperature phases, when the atomic scattering factors for ionized atoms N^−0.45, Cl^−0.81 and H^+0.315 were taken. Only the room temperature phase showed the rotatory vibration of the hydrogen atoms. The result of our experiment was compared with those of X-ray, neutron and other electron diffraction data.