The Lithium Chemistry of the Early Universe

Calculations will be presented for the abundances of Li, Li(+) , LiH, and LiH(+) during the post recombination epoch of the early universe. Atomic lithium is found to remain significantly ionized with a fractional ionization f ~ 0.5 to redshifts z as small as 10. The abundance of LiH is determined to be ~ 10(2) smaller than obtained by previous calculations due to the inclusion of a new quantal radiative association rate coefficient. Inclusion of other gas-phase reactions further reduces the LiH abundance. LiH(+) is found to be less abundant than LiH. These low abundances suggest that Thomson scattering between cosmic background radiation (CBR) photons and primordial LiH and LiH(+) plays an insignificant role in erasing CBR anisotropies. Though the densities will increase in collapsing proto-clouds, the initially small abundances may severely limit searches for highly redshifted rovibrational lines and reduce their utility for constraining the cosmological Li abundance. The new LiH and LiH(+) radiative association rate coefficients will also be presented.