X-ray photoelectron and infrared spectroscopy have been used to investigate the chemical composition of some ammonium uranates, all of which were prepared by the direct titration of uranyl nitrate solution with ammonia. Some correlation is found between the U(4f) binding energy and the pH of the solution used to prepare the uranates, and the v3 asymmetric stretching frequency for the uranyl (UO22+) ion. All samples showed the presence of ammonium ions and possibly two types of hydroxide species. Strong retention of nitrate ions was also observed for all samples.
Alan J. Paul and Peter M. A. Sherwood, "An X-Ray Photoelectron Spectroscopic Study of Some Ammonium Uranates," Appl. Spectrosc. 40, 519-525 (1986)