THE HIGH-RESOLUTION INFRARED-SPECTRA OF NAPHTHALENE-H(8) AND NAPHTHALENE-D(8) - COMPARISON OF SCALED SCF AND DENSITY-FUNCTIONAL FORCE-FIELDS

The vapour phase IR spectra of naphthalene-h(8) and -d(8) have been re corded from 450 to 3200 cm(-1), at the resolution of 0.05 cm(-1), usin g a multipass cell heated to 50 degrees C. Using the new spectral data and taking the frequencies of all Raman active vibrations from the li terature we assign all fundamentals. The experimental frequencies are compared to the theoretical ones both computed with the Self Consisten t Field method, followed by the Scaled Quantum Mechanical (SQM) method , and by the Density Functional Theory (DFT). The infrared spectrum of naphthalene is reproduced to a good accuracy with both methods leadin g in most cases to unambiguous assignments. The absolute infrared inte nsities of some fundamentals of C10H8 and the relative intensities of C10D8 have been measured and compared to those evaluated by SQM and DF T.