Molecular Physics, Chemical Physics
The evolution from gas phase to bulk can be traced by probing the properties of clusters. A cluster is an aggregate of bound atoms or molecules. Some clusters have size-dependent physicochemical properties which are different from those of the bulk. Others such as clusters of CO2 are of great interest in atmospheric and industrial chemistry. For example, under supercritical conditions CO2 is used a benign industrial solvent. These intermolecular forces can be directly probed by means of high-resolution spectroscopy. The aim is to answer basic questions such as “how do differing structures of a given cluster size influence the growth of larger ones?” and “does the system has preferred pathways?” These questions are relevant in atmospheric chemistry, biomedical, electronics, and materials science. Our experimental results also provide a challenge to quantum chemical calculations of weak forces, which thereby helps to advance the state of the theory. The theory in turn can be used for calculations on large systems of biological significance. We are also interested in the development of quantum mechanical models for frequency and intensity of ethane bands in the mid infrared region. Here, the challenge lies in understanding the basic physical questions relating to the role that large amplitude twisting of CH3 groups play in coupling the other vibrational modes. The interest in resolving such basic physical questions relates to the fact that CH3 groups are present in many larger bio-molecules and it is the motion of these groups that determine the dynamical properties and functions of these systems. The end users of our laboratory data are scientists with interest in terrestrial and planetary atmospheric remote sensing, transmission simulations, industrial process monitoring, and pollution regulatory studies.