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We studied the hyperfine components of the (J= 10–9, Kl= 9) rotational transition in the v6= 1 excited vibrational state of CH3I, using collinear infrared and mm-wave radiations. The Doppler-free double-resonance technique allowed an accurate determination of the collisional broadening parameters for all the hyperfine components. An evident dependence on the Fquantum number was observed and this result is perfectly consistent with a theoretical model allowing calculations of collisional broadening and coupling for the hyperfine components.

Measurements on broadening by nitrogen and oxygen of lines of the type J + 1_0,J+1 ← J_0,J of NO35Cl have been carried out in the region 88-700 GHz with J ranging from 7 to 64. The observed decrease of the pressure-broadening coefficients for J > 10 is reproduced by theoretical calculations on N₂ broadening performed by employing an ATC impact approximation model.Copyright 1993, 1999 Academic Press