Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA.
Phys Rev Lett. 2011 Dec 16;107(25):255503. doi: 10.1103/PhysRevLett.107.255503.
Hydrogen sulfide (H(2)S) and hydrogen (H(2)) crystallize into a 'guest-host' structure at 3.5 GPa and, at the initial formation pressure, the rotationally disordered component molecules exhibit weak van der Waals-type interactions. With increasing pressure, hydrogen bonding develops and strengthens between neighboring H(2)S molecules, reflected in a pronounced drop in S-H vibrational stretching frequency and also observed in first-principles calculations. At 17 GPa, an ordering process occurs where H(2)S molecules orient themselves to maximize hydrogen bonding and H(2) molecules simultaneously occupy a chemically distinct lattice site. Intermolecular forces in the H(2)S+H(2) system may be tuned with pressure from the weak hydrogen-bonding limit to the ordered hydrogen-bonding regime, resulting in a novel clathrate structure stabilized by cooperative interactions.
硫化氢 (H(2)S) 和氢气 (H(2)) 在 3.5 GPa 下结晶成“主体-客体”结构，在初始形成压力下，旋转无序的组分分子表现出较弱的范德华型相互作用。随着压力的增加，相邻 H(2)S 分子之间形成并增强了氢键，这反映在 S-H 振动伸缩频率的明显下降，也可以在第一性原理计算中观察到。在 17 GPa 时，发生了一个有序化过程，其中 H(2)S 分子定向排列以最大化氢键，同时 H(2)分子占据化学上不同的晶格位置。在 H(2)S+H(2)体系中，分子间力可以通过压力从弱氢键极限调节到有序氢键范围，从而形成一种由协同相互作用稳定的新型包合物结构。
