Optical spectroscopy is one of the most powerful analytical techniques for the characterisation of materials and biological samples. Raman spectroscopy, for example, is routinely used for chemical and physical measurements in materials science, geology, microelectronics and biology. It is possible to integrate spectroscopic functionalities into optical tweezers set-ups as we have seen in Section 12.1. The resulting spectroscopic optical tweezers (SOTs) permit one to manipulate and analyse a wide range of microscopic and nanoscopic particles. In particular, SOTs allow one to study biological entities found in suspension, e.g., living cells, viruses, bacteria and organelles, in their most natural environment, i.e., without need to fix them on a substrate, as shown in Fig. 15.1 for the case of normal and thalassemic red blood cells. Applications at the nanoscale include, e.g., the possibility to identify and probe the properties of a single nanostructure in situ. In this Chapter, we will give a brief account of some applications that combine optical trapping and manipulation with spectroscopic techniques.
15.1 Absorption and photoluminescence spectroscopy
15.2 Raman spectroscopy
15.3 Coherent anti-Stokes Raman spectroscopy
15.4 Rayleigh spectroscopy and surface-enhanced Raman spectroscopy
15.5 Further reading