Determination of effective refractive index of molecular diamondoids by Becke line method

The refractive index of various diamondoid powders from adamantane to hexamantane is reported by Becke line method for the first time. The variation in refractive index with increasing polymantane order can be explained by two factors: molecular refractivity (Rm) and specific molecular volume (Vm) with increasing polymantane order. The dispersion properties with increasing polymantane order was investigated. They can be closely related to the Kitaigorodskii packaging coefficient and density as a function of polymantane order.