
Colloidal quantum dots, viruses, DNA and all other nanoparticles have acoustic vibrations that can act as 'fingerprints' to identify their shape, size and mechanical properties, yet high-resolution Raman spectroscopy in this low-energy range has been lacking. Here, we introduce extraordinary acoustic Raman (EAR) spectroscopy, a new technique to measure the Raman-active vibrations of single isolated nanoparticles in the 0.1-10 wavenumber range with 0.05 wavenumber resolution. We use this technique to resolve the peak splitting from material anisotropy in titania nanoparticles and to specifically resolve the normal mode vibrations of proteins and DNA in the extremely high frequency range (>30 GHz) and below. EAR employs a nanoaperture laser tweezer that can select particles of interest and manipulate them once identified. We therefore believe that this nanotechnology will enable expanded capabilities for the study of nanoparticles in the materials and life sciences.

Colloidal quantum dots, viruses, DNA and all other nanoparticles have acoustic vibrations that can act as 'fingerprints' to identify their shape, size and mechanical properties, yet high-resolution Raman spectroscopy in this low-energy range has been lacking. Here, we introduce extraordinary acoustic Raman (EAR) spectroscopy, a new technique to measure the Raman-active vibrations of single isolated nanoparticles in the 0.1-10 wavenumber range with 0.05 wavenumber resolution. We use this technique to resolve the peak splitting from material anisotropy in titania nanoparticles and to specifically resolve the normal mode vibrations of proteins and DNA in the extremely high frequency range (>30 GHz) and below. EAR employs a nanoaperture laser tweezer that can select particles of interest and manipulate them once identified. We therefore believe that this nanotechnology will enable expanded capabilities for the study of nanoparticles in the materials and life sciences.