Experimental evidence for the existence of a second partially-ordered phase of ice VI.

Ice exhibits extraordinary structural variety in its polymorphic structures. The existence of a new form of diversity in ice polymorphism has recently been debated in both experimental and theoretical studies, questioning whether hydrogen-disordered ice can transform into multiple hydrogen-ordered phases, contrary to the known one-to-one correspondence between disordered ice and its ordered phase. Here, we report a high-pressure phase, ice XIX, which is a second hydrogen-partially-ordered phase of ice VI.

Ice I without stacking disorder by evacuating hydrogen from hydrogen hydrate.

Water freezes below 0 °C at ambient pressure ordinarily to ice I, with hexagonal stacking sequence. Under certain conditions, ice with a cubic stacking sequence can also be formed, but ideal ice I without stacking-disorder has never been formed until recently. Here we demonstrate a route to obtain ice I without stacking-disorder by degassing hydrogen from the high-pressure form of hydrogen hydrate, C, which has a host framework isostructural with ice I.

Reaction Sites of CO on Size-Selected Silicon Oxide Cluster Anions: A Model Study of Chemistry in the Interstellar Environment.

We present reactions of size-selected free silicon oxide cluster anions, SinOm(-) (n = 3-7, 2n - 1 ≤ m ≤ 2n + 2), with a CO gas. Adsorption of CO on SinOm(-) is observed as a major reaction channel. The rate constant of the adsorption reaction is high for the oxygen-rich clusters with m ≥ 2n + 1, whereas almost no reaction product is observed for m ≤ 2n.