Raman microscopy / Рамановская микроскопия

It is no surprise to see the micro-Raman Group at Lille come forth with this timely publication to document the present state of Raman microscopy. A quarter century has passed since the early attempts at Raman microsampling when the field began to merge with, and complement, other microprobe techniques. In the late 1960s to the early '70s, it was mainly the electron beam methods that opened up the microscopic domain to instrumental analysis, aside from classical light microscopy. In this realm, the principal goal was to obtain morphological, structural, and compositional information from the analyzed specimen. Scanning electron microscopes (SEMs), electron microprobes for x-ray microanalysis (EPMA), and analytical electron microscopes (AEMs) furnished detailed images of the sample and elemental compositional data from microscopic sampling volumes, for nearly all of the elements in the periodic table. Yet, at that time, one important piece of information was not available from any of these methodologies: the ability to link the compositional data to the atomic or molecular bonding of the elements, their speciation, such as structural coordination and stoichiometry, as well as crystallographic and amorphous structure. This analytical need for spatially resolved information on structure and bonding of the constituent elements brought forth the development of vibrational microspectroscopy. Infrared spectroscopy, of the non-Fourier transform (FT) variety, was widely used at the time, but infrared microspectroscopy was to fully emerge only in the late 1970s with the increasing use of FT-infrared instrumentation. Since the early 1960s, Raman spectroscopy had experienced a renaissance with the advent of the laser as the ideal excitation source. Laser radiation, from the near-ultraviolet across the visible spectrum, could be focused to the optical diffraction limit, for probe spots competitive with electron probing. Thus, it was then recognized that laser excitation utilizing optimally designed fore-optics and coupled to Raman instrumentation employing various types of sensitive detectors, would make possible Raman microspectroscopy and microscopy. This concept, and its earliest implementation, initiated the new frontiers of molecular Raman probing and imaging, to complement the elemental microprobe techniques with their imaging variants.  <...>