Welcome to Molecular Beam Spectroscopy Laboratory!!!
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Research Interest:
We are in the process of setting up a strong interdisciplinary research program in experimental physical chemistry and our research interests will span a broad range of areas covering the application of several spectroscopic techniques to investigate the gas phase molecules/complexes which are important in atmospheric chemistry as well as in biological chemistry. Research projects in our laboratory will be directed towards investigating the gas phase spectroscopy and dynamics of the isolated molecules and their clusters. Both electronic and infrared spectroscopy in combination with laser induced fluorescence and time of flight mass spectrometric detections will be performed extensively to explore largely the structures, vibrations, photochemistry and photophysics of important isolated molecules and in particular, their hydrogen-bonded (H-bonded) and van der Waals complexes. In case of biologically related molecules, depending upon the size and nature of the molecules such as whether the molecules are non-volatile or thermo-labile, where cold gas-phase molecule preparation in supersonic jet environment does not work well, laser desorption method will also be coupled with mass spectrometric detections. In addition, quantum chemistry calculations will also be performed extensively to support our experimental results as well as for the preliminary investigations of systems/problems those we will address in our laboratory.
Project I:
Infrared spectroscopy, photochemistry and dynamics of several important molecules and their H-bonded complexes related to atmospheric chemistry
This project is devoted to improve our understanding the atmospheric chemistry at the molecular level. In our atmosphere, the energy comes from the sun mainly in the form of visible light and when this light reaches our earth through atmosphere, earth-surface becomes warm and radiate infrared radiation back into space in the form of heat. Therefore, infrared spectroscopy including both the fundamental and overtone transitions of the atmospheric constituents and their complexes in the laboratory, which are interconnected with atmospheric measurements, is highly important. In this research project State Resolved Photo-Dissociation Spectroscopy, commonly known as Vibrational Mediated Photodissociation (VMP) Spectroscopy will be performed extensively via the combinations of lights such as infrared, visible and ultraviolet (Figure 1). The VMP spectroscopy is known as a powerful and sensitive technique to record the infrared spectra over other various direct absorption techniques such as conventional FT-IR spectroscopy, laser photoacoustic spectroscopy or cavity ring down spectroscopy. It is worth noting here that higher overtone absorptions of atmospheric species containing OH/NH/CH groups fall in visible region of sun light and molecules containing OH chromophores are always under the attention of atmospheric chemistry because in presence of both UV and visible lights these molecules may lead to OH radicals, known as the primary sink for atmospheric pollutant. Furthermore, it has been also claimed that absorption of solar radiation by hydrogen-bonded (H-bonded) complexes, particularly those containing water, in the earth atmosphere is significant to climate change and H-bonded complexes can potentially influence climate through the absorption and scattering of solar radiation. Infrared spectroscopy can, in principle, provide a direct window to probe the H-bonded stretching coordinate of these complexes. To measure the infrared spectra of several important molecules and their H-bonded complexes related to atmospheric chemistry, we are in the process to develop the successful set up for the Vibrational Mediated Photodissociation (VMP) Spectroscopy.
Project II:
Electronic and infrared spectroscopy of small units of biologically related molecules and H-bonded complexes mimicking nucleobase pair analogues
This project is devoted to learn precisely about their intrinsic hydrogen-bonding/stacking/van der Waals interactions and dynamics via hydrogen-bonding interfaces. In this research project, various convenient species/systems will be designed and generated in the gas phase by either supersonic jet or laser desorption environments to get good testing grounds in resolving many of the complexities found in larger complex molecular network. Intramolecular NH/OH-stretching fundamental vibrational frequencies of intramolecular H-bonded molecules as well as inter-moleculer H-bonded complexes will be measured by the use of sophisticated double and triple resonance techniques such as IR-UV and IR-UV-UV.
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