Soft X-ray emission spectroscopy provides information about elemental composition, including the light elements, as well as the chemical bonding. The probe depth reaches hundreds of nanometers but under certain conditions considerable surface sensitivity can be attained. For electron impact excitation, the probe depth can be varied by variation of the electron energy, and by Variation of the detection angle. The highest surface sensitivity is obtained when the emission angle is near the critical angle for total reflection. In this case the effective probe depth is of the order of a few wavelengths, typically around 3 nm for 3d transition element L emission. In the present study we show the feasability of using the angular dependence as a means to study the thickness and composition of layered samples by comparing the experimental data to model calculations based on the X-ray optical constants of the constituent materials.