Presence of
water is supported by its bending vibrations occurring at the band 1630 cm-1
(Banwell et al 1994). The bands below 1300 cm-1 are due to PO4 vibrations.
The FTIR spectrum of 1 mol% K2CO3 added KDP shows slight decrease in
intensity for all the peaks. It is attributed to neutralization of acidic OH group
of KDP by K2CO3. In the spectra of 5 and 10 mol% of K2CO3 added KDP,
there is drastic change for the band appears just below 1000 cm-1 in the
spectrum of KDP. Hence the OH groups might be much more neutralized
than in 1 mol% doped KDP. Neutralization of OH groups by K2CO3 might be
the cause for enhanced NLO property, as electron delocalization to be much
more enhanced than pure KDP. Hence the added K2CO3, taken as dopant,
enhance the NLO property by neutralization.