Knowledge Bank

The infrared spectra of ammonia and the ammonia-chlorine (1:1) complex have been studied in solid nitrogen at temperatures between 6 and $20\circ K$. The E symmetric vibrations show a characteristic fine structure at low temperatures, both for free and complexed ammonia. The fine structure components broaden reversibly at higher temperatures. The low temperature spectrum can be interpreted as evidence for restricted rotation of ammonia around its $c3$ axis, with a sixfold potential barrier.