SPECTROSCOPY OF HIGHER VIBRATIONAL-STATES AND LIBRATIONAL SIDE BANDS OF OH IN LINBO3

The fundamental transition DELTAG01 and the higher transitions DELTAG02 and DELTAG03 are investigated in their polarization and temperature dependence. The spectral position of the transitions follows closely a Morse potential with D(e) = 4.75 eV and the mechanical anharmonicity omega(e)x(e) = 88.5 cm-1 leaving no room for speculations about possible hydrogen bonding. The intensity ratio of higher vibrational transitions indicates a strong temperature dependence of the electrical anharmonicity. An absorption side band at 4436 cm-1 which follows in intensity the absorption of the DELTAG01 transition (and therefore the OH concentration), is identified as a vibrational + librational combination side band. Its polarization displays a 3-dimensional behaviour with an intensity ratio I perpendicular-to/I parallel-to almost-equal-to 2 with respect to the z over arrow pointing right-direction. The librational frequency is an important input parameter for the discussion of the protonic conductivity.