Spectra of carbon monoxide in the interior of heme proteins are dominated by the internal electric field. Peak shifts and splittings are inherent information about binding sites, occupation, barriers and orientation. Additionally, pathways to the heme iron can be identified by temperature dependent rebinding experiments. Because the dipole autocorrelation function is connected with the lineshape of the absorbance spectrum a classical molecular dynamics simulation with a proper chosen CO model was carried out. Here in my work I present an identification of three discovered binding sites within Neuroglobin (Ngb) using CO as molecular probe.