Modern Raman Spectroscopy

The 2016 UK Space Agency Mars Utah Rover Field Investigation (MURFI)

“…Of the analytical instruments in the ExoMars rover Pasteur suite, only the Raman Laser Spectrometer ("RLS"; Rull et al, 2017) (Smith and Dent, 2013). The Deltanu Rockhound spectrometer was used to simulate the functionality of miniaturised Raman instruments, such as RLS on the ExoMars rover.…”

Developments in enzyme immobilization and near-infrared Raman spectroscopy with downstream renewable energy applications

“…About 1 in every 1 million photons is inelastically scattered with a shift in energy relative to the incident source that is characteristic of specific vibrational modes in a molecule. [56][57] This process is called either Stokes or anti-Stokes scattering, dependent upon whether the excited molecule has absorbed some of the energy, and has been promoted to a higher vibrational level (Stokes), or if molecules originally at higher vibrational levels relax to the ground state (anti-Stokes). [56][57] These processes are depicted in Figure 5.…”

“…[56][57] This process is called either Stokes or anti-Stokes scattering, dependent upon whether the excited molecule has absorbed some of the energy, and has been promoted to a higher vibrational level (Stokes), or if molecules originally at higher vibrational levels relax to the ground state (anti-Stokes). [56][57] These processes are depicted in Figure 5. Anti-Stokes lines are much weaker than Stokes lines due to the lower probability of molecules populating excited vibrational levels at ambient conditions.…”

“…Anti-stokes scattering occurs at higher energies (blue-shifts) since the molecule is losing energy by relaxing to the ground state. [56][57] Raman spectroscopy typically measures Stokes lines. Antistokes lines may be measured if the Stokes lines are inhibited by fluorescence.…”

“…In Raman spectroscopy, molecules are promoted to short-lived, "virtual" vibrational levels, and therefore, do not necessitate matching the excitation energy to the difference between the ground and first excited vibrational level, unless performing resonance Raman spectroscopy, where the excitation wavelength resonates with a molecular electronic state transition. [56][57] Symmetric vibrations typically have the largest change in polarizability, and therefore, are the strongest vibrational modes in a Raman spectrum. In infrared spectroscopy, asymmetric vibrations lead to the largest change in dipole, and are therefore, the most intense vibrational modes in an infrared spectrum.…”