Advances in Photoacoustic and Photothermal Techniques for Nondestructive Characterization at Nanoscopic Scale

Photoacoustic Spectroscopy (PAS) and Photothermal deflection Spectroscopy (PDS) are excellent techniques for studying the optical absorption spectra of opaque and highly light-scattering substances such as nanomaterials. In this paper we review recent advances in the methodology of PAS and its novel applications. In particular we discuss the performance of PAS to detect circular dichroism of intrinsic chiral materials [1] as well as extrinsic pseudo-chiral metasurfaces [2], showing how the selective absorption of circularly polarized light depend on the orientation of the metasurface. We also applied PAS in the VIS/IR range to measure the resonant absorption peaks related to the guided modes of GaAs-based NW on Si [3-5].