I present the latest results on extinction by diffuse interstellar dust (ID) as seen in the X-rays. The X-rays have unique advantages which makes these studies fundamental to acquire a complete picture on the ID chemistry. For example sharp and deep absorption features of Mg, Si, O and Fe, which are the building blocks of silicates, fall in the X-ray band. The shift and the structure of the absorption features are different for different absorbing dust grains. Such absorption features can in principle reveal the chemical composition, crystallinity and side of the intervening dust. However, in order to interpret the astronomical data, reliable laboratory characterisation of interstellar dust analogues are necessary. Here I present also how we carried out a large laboratory campaign, in order to obtain for the first time a complete and homogenous set of measurements in the X-ray band.
Organizer: F. Galliano