Exploring the Dynamics of Glasses Using Beta Detected NMR

Abstract

We report 8 Li spin lattice relaxation in two forms of the molecular glass TPD, one a normal glass and one prepared in an ultrastable configuration. The relaxation is remarkably fast, similar to 8 Li relaxation in other organic materials and shows a stretched exponential behavior typical of glasses with a small stretching exponent = 0.3. At low temperature, there is little or no difference between the two glasses, while above 250 K, the relaxation in the denser ultrastable form is faster. In addition, in this temperature range, the data shows a significant thermal hysteresis.

Dynamics of Liquid 1-Ethyl-3-Methylimidazolium Acetate Measured with Implanted-Ion 8Li β-NMR

“…In addition to the dynamics of the polymer backbone, certain structures admitted Li + diffusion, whose mobility was found to depend on the ionicity of the anion of the dissolved Li salt . A few small molecular glasses have also been investigated, where the relaxation is similarly fast …”

“…72 A few small molecular glasses have also been investigated, where the relaxation is similarly fast. 73 Common to all of these studies is the nonexponential decay of the 8 Li spin polarization, which is well-described by a stretched exponential. In these disordered materials, the "stretched" behavior is compatible with the interpretation of distribution of local environments, leading to an inhomogeneous SLR.…”

Magnesium(II)‐ATP Complexes in 1‐Ethyl‐3‐Methylimidazolium Acetate Solutions Characterized by31Mg β‐Radiation‐Detected NMR Spectroscopy

“…[17] While μSR is known for its utility in chemistry (see e.g., [18] ), β-NMR's uses are traditionally rooted in nuclear [19] and solidstate [11] physics, with chemical applications being relatively unexplored. Some progress to this end has been made recently, [12] with 8 Li β-NMR being used to study the glassy phase of polymers, [20][21][22][23] small molecules, [24] and room temperature ionic liquids (RTILs). [25] Similarly, several groups have now implemented setups capable of measurements in liquids, [16,[26][27][28][29][30][31] greatly expanding the scope of possible experiments.…”

Magnesium(II)‐ATP Complexes in 1‐Ethyl‐3‐Methylimidazolium Acetate Solutions Characterized by31Mg β‐Radiation‐Detected NMR Spectroscopy

“…[17] While μSR is known for its utility in chemistry (see e.g., [18] ), β-NMR's uses are traditionally rooted in nuclear [19] and solidstate [11] physics, with chemical applications being relatively unexplored. Some progress to this end has been made recently, [12] with 8 Li β-NMR being used to study the glassy phase of polymers, [20][21][22][23] small molecules, [24] and room temperature ionic liquids (RTILs). [25] Similarly, several groups have now implemented setups capable of measurements in liquids, [16,[26][27][28][29][30][31] greatly expanding the scope of possible experiments.…”