Resonance Raman spectroscopy alkali

Heating of certain alkali halides with elemental sulfur also produces colored materials containing the anions 82 or 83 which replace the corresponding halide ions. For example, NaCl and KI crystals when heated in the presence of sulfur vapor incorporate di- and trisulfide monoanions [116-119] which can be detected, inter alia, by resonance Raman spectroscopy [120, 121] ... 

In principle, deprotonation of any of the sulfanes gives polysulfide anions In practice, this route is not employed and rather fewer anions are known compared with the sulfanes. It was established last century that sulfur dissolves in basic media to give intensely colored (often blue) solutions. The well-known polysulfide solution [NH4]2Sjt, which contains mostly X = 4 and 5, is obtained by bubbling H2S through a suspension of sulfur in ammonium hydroxide. It is accepted nowadays that the blue coloration of many of these solutions is a consequence of the 83 radical. This species has characteristic EPR, visible, and Raman spectra that have enabled its detection in a variety of solutions including liquid ammonia,DMF, and HMPA. 82 can be introduced as an impurity into alkali metal halides. In lapis lazuli (lazurite that is made synthetically as ultramarine blue Na8[Al68i6024]8 , n = 2-4), the blue color is due to the presence of 83 radicals, which has also been identified by Resonance Raman Spectroscopy ... 

This means that addition of elemental E to alkali metal polychalcogenide fluxes (200-600°C) will promote the formation of longer chains as potential ligands, when such molten salts are employed as reaction media for the preparation of polychalcogenide complexes. Speciation analysis for polychalcogenides in solution has been performed by a variety of physical methods including UV/vis absorption spectroscopy, Raman spectroscopy, Se, Te and Te NMR, electron spin resonance and electrospray mass spectrometry. 

Two separate samples of NasCgo were prepared by direct reaction of Ceo with sodium metal vapor, and subjected to different annealing times of 10 16 days. C and Na solid-state NMR, along with elemental analysis, powder XRD and Raman spectroscopy, were used to characterise both samples. Na and C solid-state NMR spectra of the two samples are significantly different, suggesting a relationship between annealing times and the final structure of the alkali fulleride. Na VTMAS NMR experiments reveal the existence of two or three distinct Na species and reversible temperature-dependent diffusion of sodium ions between octahedral and tetrahedral interstitial sites. C MAS NMR experiments are used to identify resonances corresponding to free Ceo and fulleride species. ... 

---