**Author details**

Eduard Fron

Director Core Facility for Advanced Spectroscopy, KU Leuven, Molecular Imaging and Photonics, Leuven, Belgium

\*Address all correspondence to: eduard.fron@kuleuven.be

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
