Russina Olga, Beiner Mario, Pappas Catherine, Russina Margarita, Arrighi Valeria, Unruh Tobias, Mullan Claire L, Hardacre Christopher, Triolo Alessandro
Istituto per i Processi Chimico-Fisici, Consiglio Nazionale delle Ricerche, Salita Sperone, C. da Papardo, 98158 Faro Superiore, Messina, Italy.
J Phys Chem B. 2009 Jun 25;113(25):8469-74. doi: 10.1021/jp900142m.
We present results from complementary characterizations of the primary relaxation rate of a room temperature ionic liquid (RTIL), 1-hexyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl} imide, [C6mim][Tf2N], over a wide temperature range. This extensive data set is successfully merged with existing literature data for conductivity, viscosity, and NMR diffusion coefficients thus providing, for the case of RTILs, a unique description of the primary process relaxation map over more than 12 decades in relaxation rate and between 185 and 430 K. This unique data set allows a detailed characterization of the VTF parameters for the primary process, that are: B=890 K, T0=155.2 K, leading to a fragility index m=71, corresponding to an intermediate fragility. For the first time neutron spin echo data from a fully deuteriated sample of RTIL at the two main interference peaks, Q=0.76 and 1.4 A(-1) are presented. At high temperature (T>250 K), the collective structural relaxation rate follows the viscosity behavior; however at lower temperatures it deviates from the viscosity behavior, indicating the existence of a faster process.
我们展示了在很宽温度范围内对室温离子液体（RTIL）1-己基-3-甲基咪唑双（三氟甲基磺酰）亚胺[C6mim][Tf2N]的初级弛豫速率进行补充表征的结果。这个广泛的数据集成功地与现有的关于电导率、粘度和核磁共振扩散系数的文献数据合并，从而针对RTILs的情况，在超过12个数量级的弛豫速率范围以及185至430 K之间，提供了初级过程弛豫图谱的独特描述。这个独特的数据集使得能够详细表征初级过程的VTF参数，即：B = 890 K，T0 = 155.2 K，得出脆性指数m = 71，对应于中间脆性。首次展示了来自RTIL全氘代样品在两个主要干涉峰Q = 0.76和1.4 Å⁻¹处的中子自旋回波数据。在高温（T > 250 K）下，集体结构弛豫速率遵循粘度行为；然而在较低温度下，它偏离了粘度行为，表明存在一个更快的过程。
