Authors:

Alex Author

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About Paper:

Dark-field and confocal approaches to circular dichroism (CD) spectroscopy of uniaxial thin films further examine the relationship between symmetry and incoherence in the nonreciprocal CD response, or the component that is antisymmetric about light propagation direction. Modifying a conventional CD spectrometer for low-angle scattering detection isolates incoherent contributions to nonreciprocal CD drop-cast thin films, boasting 5-to-10-fold enhancements in CD dissymmetry parameters. Conversely, confocal detection suppresses the nonreciprocal CD response. These collective measurements offer additional insight on relevant theoretical frameworks. Namely, they provide the first compelling evidence of early predictions by Hecht and Barron, which indicate large chiral-and-interface-specific CD observables from scattered signals in uniaxially oriented assemblies. According to this theory, nonreciprocal CD is possible within the electric dipole approximation, leading to chiral-specific observables exceeding reciprocal, isotropic contributions. Dark-field absorbance CD (DCD) spectroscopy thus offers new insights into molecular and macromolecular arrangements with interface selectivity and chiral specificity. Keywords: Surface Specificity; Interface Chemistry; Circular Dichroism; Chirality; Spectroscopy

Source:

Purdue University / 2024

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Co-authors:

Alex Author