Laboratory Studies of Candidate Interstellar Dust Materials
The discussions in Chapters 2 and 3 have shown how astronomical observations and theoretical modelling of interstellar extinction and spectroscopy can begin to define the physical and chemical nature of dust in the diffuse interstellar medium. The main components are believed to be silicates and carbons. However, such loose descriptions are imprecise, and much greater accuracy is required if the role of interstellar dust is to be properly explored. Fortunately, considerable insight can be gained from laboratory studies of suitable materials that may be regarded as potential analogues of dust grains. This laboratory work has become an essential and very active part of modern astrochemistry. In this chapter, we discuss first the physical nature of amorphous silicates and of the many kinds of amorphous carbons. We then describe some current work on the production of some dust grain analogues and of their response to ultraviolet, visible, and infrared radiation.