Microwave spectrum and analysis of 4-chloro-2-fluorophenol

Spectroscopy is the study of the phenomena that arise when molecules and atoms are stimulated by different wavelengths of electromagnetic radiation. Microwave spectroscopy uses the microwave region of the electromagnetic spectrum and measures the rotational changes that result from stimulation by this low-frequency source of radiation. These rational changes are then used to calculate the moments of inertia of the molecule, telling us the shape. We used the GSSM’s fourier transform chirped-pulse microwave spectrometer to study 4-Chloro-2-Fluorophenol’s shape. 4-Chloro-2-Fluorophenol has two conformations with the cis having the hydrogen from the hydroxyl group pointing towards the fluorine and the trans having the hydrogen pointing away. Calculations to determine the theoretical rotational, distortional, and nuclear quadrupole constants as well as relative energy for each conformation were run using Gaussian 03W. Then the compound was heated to ensure the compound was fully in the liquid state so it could be properly sprayed by the nozzle. Measurements were then recorded over the frequency range of 8,000 MHz to 18,0000 MHz in 1,000 MHz intervals, with 10,000 measurements being averaged for each interval. The softwares BBA and AABs were then used to fit and refine the experimental data. The rotational constants, distortion constant, and nuclear quadrupole constants were found. It was found that the experimental data more closely aligned to the calculated cis conformation indicating that the cis conformation is lower energy than the trans, which aligned with the relative energies calculated.