Discipline: Chemistry & Chemical Sciences
Subcategory: STEM Research
John Yi - Winston Salem State University
Co-Author(s): Leonardo Alvarez-Valtierra, University of Guanajuato, Mexico; David F. Plusquellic, National Institute of Standards and Technology, Boulder CO; David W. Pratt, University of Vermont
Rotationally resolved fluorescence excitation spectra of N-Methylcarbazole (NMC) has been obtained using a CW laser/molecular beam spectrometer. The band exhibits perturbation originating from the coupling of the hindered torsional motion of the methyl group and the rotation of the entire molecule. The derived values of the rotational parameters show that NMC itself has a planar heavy-atom structure with a methyl group in both electronic states. From analysis of the torsional bands obtained, several remarkable issues were found and the torsional barrier heights were calculated. For instance, the values of this type (V6, six-fold) of torsional energy barrier depend significantly on the position of the methyl group with respect to the chromophore and the barriers decrease from ground to excited electronic states. The molecule also exhibits structural changes when the molecule absorbs light, owing to photon-induced changes in the electronic distribution of the molecule. The orientations of the S1 ? S0 transition moment is parallel to the b-inertial axis and coincident with the methyl group. A detailed discussion of the relevant effects derived from our findings will be provided.
Funder Acknowledgement(s): Work supported by NSF HBCU RIA-1505311
Faculty Advisor: None Listed,