engleski

Interaction induced absorption in infrared spectra of diphenyldiacetylene

It has been known for some time that in the IR spectra of melted or dissolved diphenyldiacetylene (DPDA) two bands, 2220 and 2152 cm-1, are found while the solid IR spectrum shows only one band at 2150 cm-1, as expected from the selection rules. The wavenumber of the extra IR band coincides with the value observed in solution Raman, 2219 cm-1. This was erroneously used as an argument for the changed molecular geometry in solution . If the acetylenic bridge remains linear the symmetry of either DPA or DPDA molecules depends on the dihedral angle j, D2h (j = 0), D2 (0 < j < pi/2), and D2d (j = pi/2). The correlation between these groups shows that the A1g (D2h) C&ordm ; C mode remains only Raman active for the latter two groups as well.

induced absorption. diphenyldiacetylene; diphenylbutadiyne

nije evidentirano