Laboratory Astrophysics

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SURFRESIDE2, an UHV setup to study molecule formation on icy dust grains for dense interstellar cloud conditions.

The Leiden observatory houses the Sackler Laboratory, dedicated to recreating the extreme conditions of the interstellar medium. In this laboratory, the chemical processes taking place for example on the surfaces on interstellar ice grains can be simulated, providing benchmark data that can be used for the interpretation of observations of cold interstellar and circumstellar environments. The laboratory currently uses three NOVA funded ultra-high vacuum cryogenic setups: CRYOPAD2, SURFRESIDE2 and MATRI2CES.

CRYOPAD2 has been designed and constructed with the aim to quantitatively derive parameters that characterize the photodesorption and photodissociation in interstellar ice analogues and to derive the resulting photochemical pathways that explain the molecular complexity as observed by e.g. ALMA. Wavelength dependent photodesorption rates using the SOLEIL synchrotron facility have been obtained in close collaboration with UPMC Paris. SURFRESIDE2 is suited to study atom addition reactions under dense cloud conditions where UV light is less important and experiments have shown how both smaller (H2O, CH3OH and CO2) as well as more complex species, like glycolaldehyde (HC(O)CH2OH) and ethylene glycol (H2C(OH)CH2OH) form. MATRI2CES, based on a new approach to study interstellar ices, aims for lifting ice processing studies into the prebiotic domain where astrochemistry and astrobiology meet. Experiments in 2014 and 2015 showed that molecular complexity extends beyond the borders accessible with standard techniques.

The setups are all used at ultra-high vacuum (better than 10-12 mbar). Mixed or layered ices, compact or porous, are grown with monolayer precision. Physical (i.e., photodesorption and photodissociation) and chemical (molecule formation) processes are initiated using calibrated microwave driven H2 discharge lamps as well as atomic beam lines (H, D, N, O and also OH) that simulate interstellar radiation fields or particles impacting onto icy dust grains in space. The detection is realized spectroscopically, using reflection spectroscopy (FTIR RAIRS) or mass spectrometrically, using QMS or TOF based methods.

For more information, please visit the Sackler Laboratory website.

The Sackler Laboratory principal investigator is Prof. dr. Harold Linnartz (Leiden observatory).