High resolution infrared spectra of C212H2, C12C13H2, and C213H2

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].…”

Experimental 2CH excitation in acetylene-containing van der Waals complexes

“…This most empirical relationship, which could be severely affected by large uncertainties on the D e values, remains to be fully confirmed. Unfortunately, data on 3 in C 2 H 2 monomer and complexes cannot be used for this purpose because they are affected by the 3 / 2 þ 4 þ 5 anharmonic resonance [131]. Further relations, such as evidenced for HF hydrogen-bonded systems [132] cannot be applied to 2CH excited acetylene complexes because of the lack of appropriate data.…”

Measurement and interpretation of the absolute infrared intensities of acetylene: fundamentals and combination bands

“…The remaining area was ascribed to the vf t u4 combination band. In order to account for the Fermi resonance between vi and v2 + .v4 + v5 [12], the unperturbed intensity of the latter band was considered to be zero. Hence all intensity in the CH stretching region was assigned to the v3 fundamental mode.…”