Abstract
The optical transmittance and reflectance near the fundamental absorption region along the
c- and
a-axes of lithium potassium sulphate single crystal (LKS) are measured at room temperature. From the data the absorption coefficient (
α) and the optical band gap (
E
opt.
g) were deduced. The type of transition was determined. The steepness parameter (
σ), the temperature dependence of the energy gap and the exciton energy (
E
0) were also calculated. The extinction coefficient, the refractive index and both the real and imaginary parts of the dielectric permittivity were calculated as functions of the photon energy.