Quasilinear molecules, quantum monodromy

In addition, Winnewisser et al. [36] have demonstrated quantum monodromy for the NCNCS molecule, not only in the (vb, Ka) eigenvalues but also in the Bes = B + C)/2 rotational constant, which varies smoothly with Ka, at fixed Vb for Vb = 0-2, but shows a kink for Vb = 3-5. This observation is a key to the assignment of the extremely congested rotational spectrum of this interesting quasilinear molecule. 

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