Infrared Spectral Emittance and Optical Properties of Yttrium Vanadate

The infrared spectral emittance E of single scrystals of YVO₄ has been examined near 4.2 and 77^∘{}K in the wavelength range 4-125 {μ}m. Of the expected seven active transverse optical modes at k{~}0, six have been observed and assigned to their symmetry species based on their polarization with respect to the crystalline axes. The observed frequencies of the transverse optic Eᵤ modes were 196, 261, and 788 cm^-1; and for A₂ᵤ modes, 310, 455, and 803 cm^-1. The relation between emittance and reflectance, E=1-R in the opaque region of lattice vibrations, permits one to determine the reflectance R. By least-square-fitting the reflectance data to an independent set of damped harmonic oscillators, infrared dispersion parameters were determined for the Eᵤ vibrations.