Abstract
We have measured the normal reflection spectrum of (110) cleaved faces of single crystals of CuCl in the spectral range of the Z(3) and Z(12) exciton lines at the temperature of 95 K. We have fitted the experimental data by computing a non local dielectric function and taking into account various additional boundary conditions (ABC) and the dead layer model in a semi-infinite crystal. A quantitative agreement is obtained assuming the following values of the effective masses of the excitons: M(Z(3)) = 2.4m(0), M(Z(12)) = 0.65m(0). These results do not depend on the choice of a particular auxiliary boundary condition.