Raman spectra of the arabinonucleosides ARA‐A and ARA‐C Compared with the spectra of adenosine and cytidine

Raman spectra of the arabinonucleosides ARA‐A and ARA‐C and their protonated species have been recorded and compared with those of adenosine and cytidine and protonated adenosine and cytidine. The vibrational modes of the molecules have been studied and the characteristic frequencies have been assigned. The cis ‐ trans geometry of the sugar hydroxyl groups is clearly indicated from the Raman spectra of the solids and aqueous solutions. The lattice modes of these species are observed in the low‐frequency region of the spectra below 200 cm −1 and they, too, reflect the different puckering of the cis ‐ trans sugar hydroxy grops in the crystals.