Observation of Low-Lying Raman Bands in DNA by Tandem Interferometry

A tandem Fabry-Perot interferometer has been used to locate Raman bands at 12 ${\mathrm{cm}}^{-1\mathrm{}}$ ($B$-DNA) and 15 and possibly 12 ${\mathrm{cm}}^{-1\mathrm{}}$ ($A$-DNA). The Raman shift of these bands is dispersionless and the scattering process appears to require quasimomentum conservation. We assign these bands to the lowest-lying Raman-active optic phonons.