CHED 1436 |
| The Raman and Surface Enhanced Raman spectra (SERS) of flavone and three of its hydroxy derivatives, 3- and 5- hydroxyflavone and quercetin (3,5,7,3',4' pentahydroxyflavone) have been obtained. The normal Raman spectra are taken in the powder form. The SERS spectra are obtained on both Ag colloid and Ag electrode substrates. Assignments of the spectrally observed normal modes are aided by density functional theory (DFT) calculations using the B3LYP functional and two included pand d- functions into the 6-31+G* basis, a split valence polarized basis set with diffuse functions. Excellent fits are obtained for the observed spectra with little or no scaling. The most intense lines of the normal Raman spectra are those in the C=O stretching region (near 1600 cm-1). These lines are often weakened by proximity to the surface, while other lines at lower wavenumber, due to in-plane ring stretches, tend to be strongly enhanced. The SERS spectrum of flavone is weak on both the colloid and electrode, indicating weak attachment to the surface. In contrast, the SERS spectra of the hydroxy derivatives of flavone are intense, indicating the assistance of OH groups in attachment to the surface. The spectra of the various species are compared and a case study of application to detection of a textile dye (Persian Berries), which contains quercetin, is presented. |
|
Undergraduate Research Poster Session: Physical Chemistry
2:00 PM-4:00 PM, Monday, March 26, 2007 Hyatt Regency Chicago -- Riverside Center, Poster
Division of Chemical Education |