The majority of our knowledge of the astronomical world is derived from the emission, absorption, and scattering of electromagnetic radiation from atoms and molecules. The astronomical observations of atomic and molecular spectra including transition energies, intensities, and light polarization complemented with laboratory experiments and theoretical calculations are essential in the study of stellar atmospheres. The goal of this CNIC proposal is to catalyze an international interdisciplinary collaboration between the group of Prof. Ludwik Adamowicz, at the Department of Chemistry and Biochemistry, the University of Arizona (USA) and Prof. Jow-Tsong Shy, at the Department of Physics, the National Tsing Hua University (Taiwan) on performing very accurate experimental and theoretical studies of the rovibrational (rovib) spectra of small hydrogen-containing molecules and clusters. These systems constitute a significant portion of the mass of the universe and are key to the interstellar chemistry. The goal of this collaborative is to characterize and assign the rovibrational spectra of the studied molecular systems. The obtained data can be very helpful in identifying spectral lines recorded by telescopes and assigning these lines to particular molecules and clusters. As a result, knowledge will be gained about the compositions of various domains in the universe and about chemistry occurring there. This collaboration brings together groups with very different research profiles. The Taiwan group has been concerned with high-precision experimental spectroscopy studies of small neutral and charged molecular systems. The theoretical-chemistry Arizona group has been involved in development and application of very accurate quantum-mechanical methods for calculating spectra of small atoms and molecules. Both groups are accomplished in their respective fields. In this project, the theory and the experiment will be combined in elucidation of the spectra of molecules and clusters involving hydrogen and its isotopes. The studies are very fundamental in nature and as such they are well suited for NSF funding.