ROTATIONAL BAND CONTOURS IN 5000 A 1B1G-1AG ELECTRONIC SYSTEM OF P-BENZOQUINONE

Using the technique of computer simulation of rotational band contours the 1–0 band in v7, band E, in the 5000 Å1B1g-1Ag system of p-benzoquinone has been rotationally analysed. It is a type A band and the excited state rotational constants are: (image found) The excited state inertial defect determined from these constants is -0·8 ± 0·2 uÅ2. This value is almost certainly due not to non-planarity of the excited state but to a Coriolis interaction between v7 and perhaps the b1u vibration v13. Such an interaction, if it were weak, would affect only the A′ rotational constant. Previous assignments [2] of other type A bands and type B bands in the spectrum are reviewed where possible with the new evidence of the computed contours and the assignments remain largely unaltered. © 1969 Taylor and Francis Group, LLC.