Scientific Rationale

The isotopic fractionation, i.e., the chemical process by which less abundant stable isotopes of elements are transferred to molecules, is still not well-understood. Most of the observational and theoretical works carried out so far have focussed on the Deuterium fractionation, found to be an important evolutionary tracer in a variety of star formation environments. The sensitivity of sub-millimeter (ALMA, NOEMA, APEX, IRAM-30m) and IR (Spitzer, Herschel) observational facilities, and new chemical models are starting to shed light also on the fractionation of elements less abundant than H, with special attention to the possible link between this process and the evolution of the host environment. In particular, space missions have shown that among the most abundant elements in the Universe, three of them (hydrogen, oxygen and nitrogen) present isotopic enrichments (abundances larger than those of the Solar nebula) in comets, carbonaceous chondrites, and other pristine small Solar System bodies, which suggests a probable heritage from the early phases of the Sun formation.

The Premiale Project "Science and Technology in Italy for the upgraded ALMA Observatory - iALMA" has as one of the main goals to contribute to the development of a prototype Band 2+3 cartridge for ALMA, in cooperation with ESO and other partners. This receiver will cover the whole frequency range from 67 GHz to 116 GHz, with a broad instantaneous frequency coverage. The Band 2+3 is especially important for the study of deuterated species because the ground rotational transitions of many of them, together with those of their main species, lie in its frequency range. In the framework of iALMA, we propose a small workshop devoted to the study of not only deuteration but isotopic fractionation in general. The main goal of this well-focussed meeting will be to bring together observers, theoreticians and experimentalists interested in the fractionation of elements from any kind of astrophysical background: in particular, star formation in the Milky Way (from the early pre-stellar core phase up to the protoplanetary disk phase), small Solar System bodies, and chemical composition of Galaxies