Boreskov

OP‐4VUV PHOTOPHYSICS OF PREBIOTIC MOLECULES IN THE CONTEXTOF THE SEARCH FOR LIFE ON EXOPLANETSSydney LeachLaboratoire d’Etude du Rayonnement et de la Matière en AstrophysiqueObservatoire de Paris‐Meudon, 92195‐Meudon, FranceOne of the important aims of the study of extrasolar planets is to identify markers thatcould be associated with the presence or possible future existence of life on these far‐offobjects. Thus the identification of prebiotic molecules and elementary biotic building blocksis a valid objective [1]. Since the atmospheres of extrasolar planets is increasingly studied byspectroscopic means, permitting the prevailing physical environment, in particular themolecular and particulate content, and the local radiation field, to be determined, it isimperative to understand the viability of prebiotic and biotic molecules under theseconditions. Furthermore, these extrasolar planets will most probably also be subject toinflow of material from local comets and asteroids and these could give rise to observableeffects. These objects could also be sources for the molecular building blocks of life and theycould penetrate whatever atmosphere exists on an exoplanet and thus deliver these keymolecules to the atmosphere, the surface or any liquid haven. One must also include thepossibility that material can be transferred from one planet to another, as illustrated by theexistence of Martian and Lunar meteorites on Earth. In addition, cosmochemistry in theinterstellar medium (ISM) can be a source of prebiotic molecules that eventually aredeposited on planetary sites.I will present the results of extensive studies of the VUV spectroscopy and photophysicsof a number of molecules carried out in collaboration with the group of Helmut Baumgärtel,Free University, Berlin, at synchrotron radiation sources BESSY I and BESSY II, Berlin, andLURE, Orsay. Our studies have involved both optical spectroscopy (absorption, fluorescence)and photophysical studies such as photoion mass spectrometry (PIMS), including themeasurement of photoionization yields. Spectroscopic studies are essential for predictingobservational possibilities in astronomy and for the interpretation of laboratoryphotophysical results as well as astrophysical observational measurements. The speciesstudied fall into two groups: 1) small molecules, such as ammonia [2], formic acid [3,4],35