IR and polarized Raman spectra of CH3NH3NaSeO4 · 6H2O (MASS), NaNH4SeO4 · 2H2O (SAS), and their deuterated analogues are recorded and analyzed. In both the crystal symmetry of SeO2-4 is lower than Td. The symmetry of CH3NH+3 is lower than C3v and hydrogen bonding is strong in MASS. NH+4 is not rotating freely in the crystal lattice of SAS. SERS spectra are recorded in two types of silver colloids. Colloid 1 adsorbs MASS through the nitrogen atom of CH3NH3 group. There are two different adsorption sites for MASS in colloid 2. SAS is chemisorbed by colloid 2 through the oxygen atom of SeO2-4. Shifting and splitting observed for the internal modes of SeO2-4 on adsorption are due to the reduced local symmetry of the ion.
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