Absolute Infrared Intensities of the Ammonium Ion in Crystals

Abstract
The absolute intensities of the two infrared active fundamentals of the ammonium ion, ν3 and ν4, have been studied in several environments. Dilute solid solutions of NH4+ ions in KCl, KI, CsCl, and CsI were studied and compared with pure NH4I. After separating the effect of the net charge, the apparent bond moments ranged from 0.63 d to 0.80 d (av 0.71) and the bond dipole derivatives, ∂μ/∂r, from 2.06 d/A to 3.59 d/A (av 2.80 d/A). The bond moment is substantially the same as in NH3.