Chemical analysis 1 Chirped-pulse fourier transform microwave spectroscopies 1 Density functional theory 1 Gas-phases 1 Ground state 1 Internal dynamics 1 Internal rotations 1 Methyl group 1 Microwave spectroscopy 1 P-tolyl Phenyl rings 1 Quantum chemistry 1 Rotational spectra 1 Rotational spectroscopy 1 Supersonic aerodynamics 1 Theoretical study 1