Probing the low-frequency vibrational modes of viruses with Raman scattering—bacteriophage M13 in water

Raman spectroscopy is used to study low-wave-number $(≤20cm−1)$ acoustic vibrations of the M13 phage. A well-defined Raman line is observed at around $8.5cm−1$. The experimental results are compared with theoretical calculations based on an elastic continuum model and appropriate Raman selection rules derived from a bond polarizability model. The observed Raman mode is shown to belong to one of the Raman-active axial modes of the M13 phage protein coat. It is expected that the detection and characterization of this low-frequency vibrational mode can be used for applications in biomedical nanotechnology such as for monitoring the process of virus functionalization and self-assembly.