Theoretical Investigation of C9H9 Radicals: A Key Combustion Intermediate and A Potential Interstellar Molecule

Roy, Tarun and Maity, Surajit (2018) Theoretical Investigation of C9H9 Radicals: A Key Combustion Intermediate and A Potential Interstellar Molecule. Masters thesis, Indian Institute of Technology Hyderabad.

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Abstract

Density functional theory has been used to investigate the geometries, vibrational frequencies, rotational constants and ionisation potential of C9H9 radicals. Vertical electronic transition energies of C9H9 radicals are calculated by using time-dependent density functional theory. The adiabatic excitation energies and frequency calculations in excited state of C9H9 radicals have been done using DFT. Present results show that the most stable structure of C9H9 radicals is 1-indanyl radical. The adiabatic excitation energies and frequency calculations in excited state of 7 stable isomers (1-indanyl, 2-indanyl, 1-phenylallyl, 2-phenylallyl, 4-vinylbenzyl, 3-vinylbenzyl, 2-vinylbenzyl radical) of C9H9 radicals have been done. The computationally calculated vertical and adiabatic excitation energies of these 7 isomers are in good agreements with experimental observations. The high-resolution spectra of experimental R2C2PI spectrum at 618.2 nm and 601.4 nm have good matching with FCF data of 4-vinylbenzyl radical and 3-vinylbenzyl radical respectively. On the basis of the present calculations and results 4-vinylbenzyl and 3-vinylbenzyl radical of C9H9 radicals are most likely the carrier of the experimental R2C2PI spectra. These are the potential DIB carrier towards HD183143 and HD204827.

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