Infrared absorption spectra of MNO 3 (M Γ
Li, Na, and K) in solid Ar were recorded with a FTIR spectrometer. The absorption of KNO 3 displayed only singlet lines, at 1460.3, 1293.5, 1031.4, 828.0, 721.4, and 709.4 cm 01 , whereas that of LiNO 3 and of NaNO 3 showed doublets or multiplets due to matrix site splitting. Hence, detailed vibrational analysis of the NO 0 3 moiety was made for KNO 3 . From spectra of KN 16 O 30x 18 O x (x Γ
0-3) and K 15 NO 3 , five vibrational modes are unambiguously assigned and a bidentate structure of KNO 3 is confirmed. The line at 721.4 cm 01 , previously assigned to a B 2 mode, is reassigned to the n 3 (A 1 ) mode. A weak line at 709.4 cm 01 , of which 18 O-isotopic data are lacking, is tentatively assigned to the n 8 (B 2 ) mode. A Fermi resonance due to the n 1 (A 1 ) and a combinational band of n 7 (B 2 ) / n 9 (B 2 ) was observed for K( 18 O 18 O)N 16 O at 1465.8 and 1451.7 cm 01 . Normal coordinate analysis was performed for the five vibrational modes of all isotopic species. The results are consistent with theoretical predictions using density functional theory (B3-LYP). α§ 1997 Academic Press 2 Also jointly appointed by the Institute of Atomic and Molecular Sciprovided greatly improved resolution and sensitivity, we ences, Academia Sinica, Taiwan, Republic of China; to whom correspondence should be addressed.
found that recorded spectra of 18 O and 15 N species of KNO 3