Raman studies in NH₄H₂PO₄ and KH₂PO₄
Laser Raman spectra for NH4H2PO4 (ADP) and KH2PO4 (KDP) are presented as a function of temperature in the region above the phase transitions. Evidence is presented confirming the existance of strong coupling between the proton B2 tunneling mode and the B2 optical phonon mode in both crystals. The spectra were fit to a coupled oscillator function and the relevant fitting parameters are presented. The Debye relaxation time and soft mode frequency for the overdamped mode as well as the static dielectric susceptibility are plotted as a function of temperature. Soft mode behavior in both crystals ...
(For more, see "View full record.")