%0 Journal Article %T Spectral Resolution and Raman Q3 and Q2 cross sections in ~40 mol% Na2O glasses %+ Institut de Physique du Globe de Paris (IPGP) %A Nesbitt, H.W., W %A Henderson, G.S., S %A Bancroft, G.M., M %A Neuville, D.R., R %< avec comité de lecture %@ 0009-2541 %J Chemical Geology %I Elsevier %V 562 %P 120040 %8 2020-12-30 %D 2020 %R 10.1016/j.chemgeo.2020.120040 %K Raman spectra %K Na-silicate glasses %K Raman cross sections %K Raman line shapes %K Chemical speciation in glasses %Z Sciences of the Universe [physics]Journal articles %X There are four 29 Si NMR experimental studies published for glasses containing ~40 mol% Na 2 O and the reported Q species abundances are remarkably consistent. These results have been used to determine accurate Raman Q 3 and Q 2 cross sections for a 40.1 mol% Na 2 O glass. The Q 3 and Q 2 cross sections are respectively 1.10 and 0.95 (±0.03). The Q 2 band of the Raman spectrum is dominantly Lorentzian in shape whereas the Q 3 band is asymmetric and based on other studies, the asymmetry increases with alkali content, due primarily to alkali-BO interactions. As explanation, increase in alkali content enhances preferentially electron density over Si atoms of tetrahedra, thereby weakening Si-O coulombic interactions (i.e., force constants), which shifts the symmetric stretch of the Q 3 species to lower frequencies, producing asymmetric Q 3 line shapes. With Q 2 and Q 3 cross sections established, the high resolution of Raman spectroscopy now can be used to provide highly accurate estimates of Q species in silicate glasses and melts. %G English %2 https://univ-angers.hal.science/hal-03208382/document %2 https://univ-angers.hal.science/hal-03208382/file/1%20-%20Q3%20%26%20Q2%20species%20Cross%20Sections%20-%204rd%20Draft-2.pdf %L hal-03208382 %U https://univ-angers.hal.science/hal-03208382 %~ INSU %~ AFRIQ %~ CNRS %~ UNIV-ANGERS %~ IPGP %~ USPC %~ SORBONNE-UNIVERSITE %~ UNIV-PARIS %~ UNIVERSITE-PARIS %~ SU-TI %~ ALLIANCE-SU