Nuclear magnetic and dielectric spectroscopy of amorphous ice

在星际尘埃的表面，水可以凝结成非晶体，也就是所谓的无定形冰或玻璃冰。这种形式的冰——也就是非晶体的冰——在外太空中似乎是最丰富的。此外，除了大量的结晶冰相外，还存在几种玻璃态，其密度相差可达三分之一。加热后，在实验室中制备的低密度和高密度非晶态冰，在-135℃或更低的玻璃化转变温度附近转变为有争议的物质状态。通过研究纯的、掺杂的、充满气体的以及同位素标记的各种非晶态冰的修饰，这个项目的目标是探索旋转和平移自由度对这些玻璃转变的影响程度。为此，将采用频域，特别是时域电介质测量以及氧-17磁共振波谱，从而为超低温水中的分子运动提供补充处理方法。

On the surface of interstellar dust, water can condense as non-crystalline, so called amorphous or glassy ice. This form of ice – i.e., the non-crystalline one – appears to be the most abundant in outer space. Furthermore, in addition to the large number of crystalline ice phases, several glassy states exist that can differ in density by up to one third. Upon heating, low-density and high-density amorphous ices, as prepared in the laboratory, transform to controversially discussed states of matter near glass transition temperatures of –135 °C or lower. Via the study of pure, doped, gas-filled, as well as isotope-labeled modifications of various non-crystalline states of ice, it is the goal of this project to explore the extent to which rotational as well as translational degrees of freedom contribute to these glass transitions. To this end frequency-domain and in particular time-domain dielectric measurements will be employed as well as oxygen-17 magnetic resonance spectroscopy, thus methods that provide complementary handles on molecular motions in ultracold water.