Laboratory astrophysical and astrochemical experiments offer the unique possibility to simulate inter- and circumstellar conditions in a completely controlled environment. The availability of laboratory data on basic atomic and molecular processes is a prerequisite for the interpretation of modern astronomical observations. Which molecules are found in space and how are they identified? How are molecules formed and destroyed? What is the interaction between gas and grains, in particular the role of interstellar ices in forming simple and complex molecules? How are the molecules changed during the formation of new stars and planetary systems? These are only a few of the questions that are addressed in our efforts to combine the analysis of observational data and laboratory experiments. Recent improvements in the detection sensitivity of laboratory experiments have made it possible to simulate in a few minutes processes that take millions of years in space.
The Raymond & Beverly Sackler laboratory for astrophysics in Leiden was established in 1975 and was the first of its kind in the world. The laboratory specializes in spectroscopic experiments, both in the gas phase and in the solid state. With sensitive spectrometers in the submm, infrared and optical region of the electromagnetic spectrum, gas-phase radicals, ions and interstellar ice analogs are studied. New ultra-high vacuum machines (with pressures comparable to those found in protoplanetary disks) allow a controlled growth of pure or mixed interstellar ice analogs and simulate chemical processes that occur in and on top of the ice. Gas-phase molecules that are formed under interstellar conditions - low densities, low temperatures and high radiation fields - are often very exotic, e.g. long and linear carbon chain radicals such as HCCCCCCH+, PAH cations, and highly excited transients. These species are generated in special supersonic planar plasma expansions and recorded with ultra-sensitive spectroscopic detection techniques. The results of these experiments are directly applied to interpret ground based and satellite observations (infrared, submillimeter, optical) taken by Leiden astronomers and to guide future missions. Theoretical simulations are performed in collaboration with the theoretical chemistry group at the Leiden Institute of Chemistry.