This paper reviews the spectroscopic research on the microscopic solvation of electron, alkali metal atoms, alkali-earth metal ions, alkali-like hypervalent radicals, and biological molecules in relation to widely-spread chemical and biological phenomena in solution. Motivation for this research is to understand how the properties of molecular clusters vary as a function of size, particularly the stepwise development of condensed phase attributes, thus allowing us to bridge the gap between isolated molecules and solution. These studies revealed the elemental processes of solvation phenomena. Alkali atom systems show how the solvated electron forms in small clusters and the role of solvents. Alkali-earth atom systems provide us the answer to the ultimate question how the solvent controls the oxidation modes of metal ions. In particular, the hypervalent radicals, which are the phantom species both in the gas and solution phases, behave like alkali atom and play the key role in many chemical reactions.