[en] The exceptional intensity distribution of bands of unsymmetrical molecules like CN and CH in a comet spectra can be explained by taking into consideration the following factors: (a) the frequency of electronic absorption processes; (b) the distribution in the vibrational levels (ground state) which is a function of the nuclear temperature TI or of the equivalent radiation temperature Tλ; (c) the distribution in the rotational levels corresponding to the nuclear temperature. These factors are different functions of the heliocentric distance r.
