The formation of the first stars and quasars marks the transformation of the universe from its
smooth initial state to its clumpy current state. In popular cosmological models, the first …

We review the gas-phase chemistry in extraterrestrial space that is driven by reactions with
atomic and molecular ions. Ions are ubiquitous in space and are potentially responsible for …

The process of molecule formation in the primordial gas is considered in the framework of
Friedmann cosmological models from redshift z= 1e4 to z= 0. First, a comprehensive …

We have reviewed the chemistry and cooling behaviour of low-density (n< 10^ 4 cm^-3)
primordial gas and devised a cooling model wich involves 19 collisional and 9 radiative …

We present a refined treatment of H, He I, and He II recombination in the early universe. The
difference from previous calculations is that we use multilevel atoms and evolve the …

When our universe was about 380,000 years old, it underwent a period of recombination
and produced the first neutral atoms. This event, the recombination epoch, represents a …

The chemistry of deuterium, as well as that of hydrogen and helium, in the
postrecombination era of the expanding early universe is presented. A thorough survey of all …

Within the precise cosmological framework provided by the Λ-cold dark matter model and
standard Big Bang nucleosynthesis, the chemical evolution of the pregalactic gas can now …

The main achievements, current developments and prospects of molecular studies in
external galaxies are reviewed. They are put in the context of the results of several decades …

In this paper we discuss the effect of recombinations to highly excited states (n> 100) in
hydrogen during the cosmological recombination epoch. For this purpose, we developed a …