Measurement of the out-of-plane optical constants of a two-dimensional crystal

Abstract

The observation of the out-of-plane optical constants of a monolayer two-dimensional crystal is a challenging task. I illustrate an experimental procedure able to observe these quantities. We measure the out-of-plane surface susceptibilities of Graphene and Molybdenum disulfide monolayers. At a wavelength of 633 nm we find values of 0.6 and 1.1 nm respectively for these two atomic crystals.