INFRARED, SINGLE-CRYSTAL RAMAN, AND SERS SPECTRA OF CH3NH3NASEO4.6X2OAND NANH4SEO4.2X2O (X=H,D)

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 SeO42- is lower than T(d). The symmetr y of CH3NH3+ is lower than C3v and hydrogen bonding is strong in MASS. NH4+ is not rotating freely in the crystal lattice of SAS. SERS spect ra are recorded in two types of silver colloids. Colloid 1 adsorbs MAS S through the nitrogen atom of CH3NH3 group. There are two different a dsorption sites for MASS in colloid 2. SAS is chemisorbed by colloid 2 through the oxygen atom of SeO42-. Shifting and splitting observed fo r the internal modes of SeO42- on adsorption are due to the reduced lo cal symmetry of the ion. (C) 1994 Academic Press, Inc.