Spectroscopy and dynamics of cold and ultracold molecules

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Cold molecule research has grown rapidly in the last ten years, inspired by the breakthroughs in the field of ultra cold atoms. Since pronounced quantum effects emerge from thermal averages at low temperatures, cold molecules are expected to behave quite differently from those at high temperatures. Molecules have many special features that atoms do not have, i.e. rotational and vibrational motions, longer range multipole interactions, and richer chemical reactivities. Ensembles of cold molecules are therefore a treasury of new frontiers in both chemistry and physics; completely unavailable by any other means. Since it is still difficult to create molecules even at 1 K, my research in the last five years has mainly focused on developing new experimental techniques to create cold molecules. Very recently we have succeeded in trapping cold polyatomic free radicals in a magnetic trap for the first time in the world. Based on the techniques we have established and new original ideas, we will continue on the cutting edge research on cold molecules, aiming to achieve major breakthroughs in this newly emerging field.****My project in the next five years will consist of five topics: 1) Development of techniques to make ultracold molecules below 1 mK, 2) Detailed study of cold collisions and reactions, 3) Ultra-high resolution spectroscopy of cold molecules, 4) Coherent control of cold molecules by laser fields, and 5) Spectroscopy and dynamics of cold molecules in quantum condensed phases. Through these studies, new phenomena intrinsic to cold molecules will be investigated, such as quantum tunneling effects and the wave nature of molecules. Experiments on cold collisions and reactive scattering would take us into a strange new world in chemistry, namely ultracold chemistry, which may be relevant to interstellar chemistry. Coherent control such as the enantiomeric purification of racemic mixtures by laser fields is an important application of cold molecules to be tackled, which would make an impact in analytical and pharmaceutical science. Other applications include the observation of small energy differences in chiral molecules, and the development of quantum simulators/computers. The former would contribute to the understanding of the origin of life, and the latter to the material and information sciences. Furthermore, we will challenge the creation of a molecular Bose-Einstein condensate, a new phase of the molecular matter wave which has never been observed. Studies of cold molecules open unlimited possibilities, in terms of not only basic natural sciences, but also practical applications contributing to the broad scientific community, which offer a completely new field of research in physics and chemistry. **