Raman spectra of solid nitrogen and of mixed N2–rare gases (RG-Ar, Kr, Xe) are investigated over a concentration range as wide as allowed by the pertinent experimental conditions. Both the v(N2) and the lattice-mode region are studied. The effects of changes in RG impurity concentrations and temperature variations are described. Results are discussed in terms of "matrix effects," like frequency shifts, on one hand and "solid-state" effects, like resonance splitting of the vibrational transition, vibron–phonon coupling, and one- and two-phonon transitions, on the other.
Transition frequency shifts with fine-structure constant variation for Fe I and isotope-shift calculations in Fe I and Fe II