77Se solid-state NMR investigations on As(x)Se(1-x) glasses using CPMG acquisition under MAS

⁷⁷Se (I=1/2) solid-state NMR is a very sensitive probe of the local structure of selenide glasses, which themselves are promising for optical applications. In this work, we show that although ⁷⁷Se has a low natural abundance (7.58%) and a wide spectral range, the sensitivity can be dramatically increased using Carr–Purcell–Meiboom–Gill (CPMG) trains of rotor-synchronized π pulses during the detection of ⁷⁷Se magnetization but may be affected by chemical shift anisotropy when the Magic Angle Spinning rate is not fast enough and by offset effects. The indirect dimension of the T₂^CPMG-resolved spectrum shows a strong influence of the J-couplings between naturally occurring ⁷⁷Se pairs. The resulting spectra show that the structural model known as “chains crossing model” is not entirely suitable to describe the glassy network of the Se-rich compositions.