CHEM01200604005 A. K. Pathak - Homi Bhabha National Institute

eappear. Both the bending and inversion mode is seen in the weighted average scaled IR
spectra of K.5NH 3 cluster (see Fig.6.3-E). The IR spectra of K.5NH 3 cluster also consists
of strong peak at N-H stretching region. The features of the weighted average scaled IR
spectra of K.6NH 3 cluster (see Fig.6.3-F) is very similar to that of K.6NH 3 cluster. In all
the IR spectra of K.6NH 3 cluster (n =1-6) the bending and stretching bands are red shifted
(Δν = -) and inversion band is blue shifted (Δν = +) compare to that of free ammonia
molecule. It is also interesting to observe that in the N-H stretching region the major
contribution to the peak is from symmetric mode for all the ammoniated clusters, K.6NH 3
(n =1-6). On the other hand the major contribution to the peak due to N-H stretching for
free NH 3 molecule is due to the asymmetric mode.
NH 3
K(NH 3
)
IR Intensity
0 1000 2000 3000 4000
Frequency (cm -1 )
A
B
K(NH 3
) 2
K(NH 3
) 3
IR Intensity
IR Intensity
IR Intensity
0 1000 2000 3000 4000
Frequency (cm -1 )
0 1000 2000 3000 4000
Frequency (cm -1 )
C
0 1000 2000 3000 4000
Frequency (cm -1 )
D
Fig. 6.3 (Contd.)
104