Low-frequency Raman spectra of even and odd monosubstituted n-alkanes have
been recorded. Longitudinal acoustic modes (LAM) arising from whole-chain v
ibrations are described. Effects of chain length, end-group mass and temper
ature on the frequencies of these vibrations are discussed. The single-node
LAM-1 frequencies are interpreted in terms of the chain model of Minoni an
d Zerbi, and are correlated with the crystal structures indicated by the hi
gh-frequency Raman spectra of the compounds.