Question

Identify the peaks for Raman or Rayleigh on a emission/excitation spectrum for dilute quinine and for dilute sulfuric acid.

spectra are not provided

Answer 1

Quinine is a strongly fluorescing organic compound that is often used in various analytical chemistry and instrumental analysis courses to illustrate the fundamental principles and analytical applications of molecular fluorescence spectroscopy.

The Raman or Rayleigh spectra consideration, all the peaks observed in the excitation and emission (fluorescence) spectra can be assigned to one or more of several causes: absorption and subsequent fluorescence by quinine; Rayleigh (and Tyndall) scatter of the exciting wavelength; a water Raman line at a wavelength slightly longer (3380 cm-I) than the exciting line: and several peaks due to the overlapping second-order.

Sulfuric acid

The absorption spectra of sulfuric acid From this point HS04,-ip decreases; H2S04 increases in the acid direction, and HS04,-aq and increase in the aqueous direction. The experimental spectra bear this out: at 80.10% H2S04 the HS04,-ip peaks at 1040, 900, 590, and 420 cm-I are the only ones present; at 75.05% the 987 cm-1' peak is just visible as a shoulder on the 1040 cm-1' peak, and at 84.26% the 916 cm-1' H2S04 peak is becoming noticeable as an increase in intensity and a shift in Vmax of the broad 900 cm-1 peak.