A researcher plans to record the first three rotational absorption lines of gaseous carbon monoxide, CO(g), at 298 K.
Rotational energy levels for a rigid diatomic rotor are given by EJ=BJ(J+1), where B is the rotational constant and J is the rotational quantum number. For CO, B=1.93cm−1. (You do not need to perform a numerical calculation of transition energies for this question.)
(a) Identify the region of the electromagnetic spectrum in which the spectrometer must operate to observe the J=0→1, 1→2, and 2→3 transitions of CO.
(b) Describe, with reference to the spacing between adjacent rotational energy levels and to the relationship among photon energy, wavelength, and frequency, why these rotational transitions fall within the region you specified in part (a). Your explanation should cite the order‐of‐magnitude energies involved in rotational motion of small molecules.