Molecular constants for the bending modes of acetylene 12C2H2

Spectral patterns and ultrafast dynamics in planar acetylene

“…Many resonances have been detected in acetylene spectra using various excitation techniques [18][19][20][21]. With bends-only excitation, all the spectroscopically important couplings turn out to be among states with quanta only in the bend modes [15,22].…”

“…With excitation of the C-C stretch as well as the bends, coupling is possible to the C-H stretch modes. The most important of these is the 2345 resonance coupling [18,19]V 2345 , which transfers one quantum each of the C-C stretch ν 2 , trans bend ν 4 , and cis bend ν 5 to the antisymmetric C-H stretch ν 3 . Then with involvement of the C-H stretch ν 3 viaV 2345 , a third important coupling is the Darling-Dennison resonance between the stretches,V DD−stretch , typically extremely prominent in coupled stretch systems, because of its connection to the transition from normal to local modes [31,32].…”

A study of the bending motion in tetratomic molecules by the algebraic operator expansion method

“…The expansion of V (r 1 , r 2 , ϕ) of Eq. (5) is similar to the conventional expansion, 49 except that the expansion is not in powers of r 1 , r 2 , and ϕ but in terms of functions of r 1 , r 2 , and ϕ.…”

Vibration–rotation alchemy in acetylene (12C2H2), at low vibrational excitation: from high resolution spectroscopy to fast intramolecular dynamics

“…The rotational l-type resonance connects sub-states related by ∆k = ±2, with matrix elements scaling as J(J+1) 62,63,64,65 . The resultant mixing of the basis states is illustrated in Figure 2 for the {0,2,k e ,e,u} polyad.…”