Laser frequency dependence of broad backgrounds in Raman spectra of Pd/Mg(Al)O

Raman spectra have been obtained for three different stoichiometric compositions of Pd/Mg(Al)O. Two different laser wavelengths, 1064 and 514.5 nm. were used, All three compounds showed an intense background with laser excitation in the near-infrared region. The broad backgrounds were reduced as the laser excitation wavelength was decreased. The near infrared spectrum (5000-11 000 cm(-1)) of Pd/Mg(Al)O was recorded, This spectrum showed that the material contains OH-groups may be even water, It is proposed that luminescence from overtones and combination levels of OH-groups are responsible for the very different appearance of the Raman spectra, (C) 1999 Elsevier Science B.V. All rights reserved.