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“Surface Enhanced Raman Spectra in Art and Archaeology: Flavone and Several Hydroxy- Derivatives”
We are currently in the process of examining the Raman and surface enhanced Raman spectra (SERS) of several compounds of interest in studies in the conservation of art objects as well as objects of archeological interest. Due to their natural yellow color and unique chemical properties, flavones and flavonols were common chromophores in natural yellow dyes that were used in textile industry for the past 150 years. Extracted from plants, they are easily hydrolyzed from sugar derivatives to their parent flavonoid and can be applied to textiles as mordant dyes. Known for their active role in photosensitization, energy transport and cellular metabolism, many of flavone derivatives are ingredients for biochemical and pharmacological products used as human diet supplements.
Although many of the flavone derivatives have been studied by IR spectroscopy, the counterpart Raman spectra have not been obtained in many cases. This is due to the fact that as they are quite useful as dyes, they thus exhibit strong fluorescence, overwhelming the Raman intensity. Surface enhanced Raman spectroscopy increases the Raman signal while simultaneously suppressing the fluorescence, making it ideal for the study of flavones. Furthermore, although the most important applications for flavones involve highly substituted hydroxyl- derivatives, relatively little is known about the parent, unsubstituted compound, flavone itself.
In order to better understand the spectra of the poly substituted derivatives, we have undertaken a study of flavone, 3- and 5- hydroxyflavone and the penta substituted conpound quercitin (3,5,7,4’5’ pentahydroxyflavone). We present the normal Raman, SERS (both on colloid and electrode, where possible) of these four compounds, utilizing modern calculational techniques of density functional theory (DFT) to assign the normal modes. Some of the similarities and differences of the spectra are explored, and the changes in normal mode frequencies on hydroxyl substitution are examined.
- Harvard University (Ph.D. 1967)
- Cornell University (A.B. 1964)
- Honors include Research Fellow of Committee for scholarly communications with The People’s Republic of China to study in Beijing, invited lecturer and guest at the laser laboratories, Institute for Chemistry, Chinese Academy of Sciences, Predoctoral Fellowship, National Institute of Health, Teaching Prize in Physical Chemistry (Harvard University), Outstanding Lecturer (University of Illinois), Predoctoral Fellowship (Harvard University) and George Caldwell Award for Excellence in Chemistry (Cornell University).
- Member of Inter-American Photochemical Society and Sigma XI.
- Has 150 research publications from 1964 to present.
- Research Interests: Electronic structure and spectra of diatomic and polyatomic molecules using high resolution spectroscopic techniques; theoretical studies in the momentum representation in quantum mechanisms; use of laser in optical spectroscopy; light scattering; surface enhanced Raman Scattering; transition metal clusters.
- Contact Information: Telephone: 212-650-6032;e-Mail:lombardi@sci.ccny.cuny.edu
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