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，即所谓的无定形或玻璃状冰。这种形式的冰-即，非水晶体--似乎是外太空中最丰富的。此外，除了大量的结晶冰相外，还存在几种玻璃态，它们的密度相差可达三分之一。在加热时，低密度和高密度的无定形冰，如在实验室中制备的，转化为有争议的讨论状态的物质接近玻璃化转变温度-135 °C或更低。通过研究纯的，掺杂的，充气的，以及同位素标记的各种非晶态冰的修改，这是该项目的目标，以探索在何种程度上旋转以及平移自由度有助于这些玻璃化转变。为此，将采用频域，特别是时域介电测量以及氧-17磁共振光谱，从而提供超冷水中分子运动的互补处理方法。

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.