Simulation of Raman Spectra with the program TROVE
Final Report Abstract
In order to understand the many environments occuring in the Universe, one needs to know their molecular constitutions. Beyond determining what is there, an essential element to the successful analysis of such an environment is to know precisely how much is there. Molecular spectroscopy allows one to obtain information about molecules by analysing their interaction with light, in particular their absorption and emission of light. Since light can travel long distances before being detected and analysed , spectroscopy is ideally suited for remote sensing - one can identify molecules in locations not easily accessible, such as the upper layers of the Earth's atmosphere, interstellar clouds, and the atmospheres of other planets, comets and of cool stars. Not only can one use spectroscopic methods to determine what is there, but also how much is there. However, the interpretation of remote-sensing experiments requires that some prior knowledge of the target molecules is available: What are the characteristic parts of the energy level pattern of a given molecule and how much energy does the molecule absorb or emit when it makes a transition between two states? Attempts of answering these questions by spectroscopic experiments in the laboratory may be hampered by the fact that for a hitherto unknown molecule one simply does not know what one is looking for. Theoretical simulations of laboratory spectra, such as those carried out with our program system TROVE, assist the understanding of laboratory and remote-sensing molecular spectra. In the present work, we have extended TROVE with a module allowed Raman spectra to be simulated. Raman spectra complement absorption/emission spectra in that they contain information not accessible in absorption and emission. We have validated the Raman module by simulating spectra of the methyl radical CH3, one of the most important unstable molecules in existence. The comparison of the simulations with the available experimental data is very satisfactory. As a by-product of the present work, we have simulated absorption/emission spectra of CH3 with the aim of assisting the interpretation of remote-sensing experiments. Meanwhile, we conduct a similar, but more complicated project about absorption/emission spectra of the molecule ethane H3CCH3.
Publications
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Theoretical Molecular Spectroscopy of the Methyl Radical, Ph.D. dissertation, Bergische Universitat Wuppertal 2018
A. Y. Adam
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A variationally computed IR line list for the methyl radical CH3, J. Phys. Chem. A 123, 4755-4763 (2019)
A. Y. Adam , A. Yachmenev, S. N. Yurchenko , and Per Jensen
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Non-resonant Raman spectra of the methyl radical 12CH3 simulated in variational calculations, J. Mol. Spectrosc. 362, 77-83 (2019)
A. Y. Adam , Per Jensen, A Yachmenev, and S. N. Yurchenko
