  Pressure-dependent Raman scattering studies in the range 0.0 -- 32 kbar were
carried out in L-alanine in order to investigate its external mode phonon
spectra in relation to the phase transitions in the crystal. A careful analysis
of the spectra shows that the low-energy Raman modes exhibit variation both in
frequency and in intensity and between 26 and 28 kbar it is observed a
splitting of a external mode, indicating that the D_2 normal phase undergoes a
transition. Pressure coefficients for external modes are also given.
