PRIMORDIAL LIH - THE CHEMISTRY IN A COLLAPSING PROTOCLOUD

We analyse and discuss the evolution of primordial molecules during th e beginning stage of the early cloud formation using an updated primor dial lithium chemistry. As Puy & Signore (1996)[A & A, 305, 371], (199 7)[NewA, 2, 299], we consider a simple model of a collapsing protoclou d after the recombination epoch but paying special attention to the Li H formation by radiative association from excited Li atoms. Because th e rate of LiH destruction through collisions with H atoms is only esti mated we find that, at present, the percentage of primordial lithium c onverted to LiH is quite uncertain. (C) 1998 Elsevier Science B.V.