Surface-Enhanced Vibrational Spectral Study of Extracts of Hibiscus Leaves on Gold and Silver Surfaces

Abstract

Extracts of hibiscus leaves were analyzed by deposi­ting on Au or Ag surfaces and subsequent measurement of their surface-enhanced Raman and IR spectra. The spectra reflect different composition of the extracts depending on polarity of the solvents used. The Raman spectra show characteristic bands of plant pigments while the IR spectra correspond to compounds in the cuticular waxy layer. The spectra obtained on Au and Ag surfaces show the bands of the same species while the spectral backgrounds are diffe­rent. The adsorption/desorption cycles were also studied. The principal component analysis shows that the extracted compounds are mostly bonded by physisorption.