[en] This thesis investigates the pure rotation spectrum of methyl fluoride, especially with regards to the experimental behaviour of the line width as a function of the line number. The spectrum was determined over a wide range of frequencies, enabling 35 rotational transitions to be analysed separately. The total program of measurements consisted of four series in pure CH₃F and in a number of mixtures with helium, as a function of temperature and pressure. The temperature was varied between 0 and 100⁰C, the pressure between 0 and 3 atm. The analysis of the measurements indicates that the maximum in the line width is caused by resonance collisions. The experimental data is compared with a number of the available theories of the causes of line broadening. (C.F.)