Comparative FTIR spectroscopy of HX adsorbed on solid water: Ragout-jet water clusters vs ice nanocrystal arrays.
Comparative FTIR spectroscopy of HX adsorbed on solid water: Ragout-jet water clusters vs ice nanocrystal arrays.
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固体水中吸附的 HX 的 FTIR 光谱对比：Ragout-jet 水簇与冰纳米晶体阵列。
DOI：
10.1021/jp044212k
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
V. Buch
中科院分区：
文献类型：
--
作者：
J. Devlin;M. Farnik;M. Suhm;V. Buch
除了揭示HCl和HBr（HX）与水的最小混合团簇的拉伸模式带外，密集混合水-酸超音速射流的ragout-jet FTIR光谱还包括HX与较大水团簇相互作用产生的带。有人认为，在这里，低射流温度防止水簇结合HX分子成为充分溶剂化诱导离子解离。HX的分子性质可以直接从观察到的从HCl到HBr的变化和从用D2 O代替H2O的影响中推导出来。此外，HX的谱带位置与100 K以下吸附在冰表面上的分子HCl和HBr的谱带位置大致一致。同样有趣的是，在<60 K时，HX带的位置和宽度与结合在非晶冰膜表面的HX的位置和宽度接近。虽然计算结果表明，在射流膨胀中观察到的吸附HX分子通过与表面悬挂氧原子的单配位而被弱扭曲，但飞行轨迹表明簇骨架经历大振幅低频振动。局部HX溶剂化，质子共享的程度，和HX振动光谱进行严重的调制在皮秒的时间尺度。
In addition to revealing the stretch-mode bands of the smallest mixed clusters of HCl and HBr (HX) with water, the ragout-jet FTIR spectra of dense mixed water-acid supersonic jets include bands that result from the interaction of HX with larger water clusters. It is argued here that low jet temperatures prevent the water-cluster-bound HX molecules from becoming sufficiently solvated to induce ionic dissociation. The molecular nature of the HX can be deduced directly from the observed influence of changing from HCl to HBr and from replacing H2O with D2O. Furthermore, the band positions of HX are roughly coincidental with bands assigned to molecular HCl and HBr adsorbed on ice nanocrystal surfaces at temperatures below 100 K. It is also interesting that the HX band positions and widths approximate those of HX bound to the surface of amorphous ice films at <60 K. Though computational results suggest the adsorbed HX molecules observed in the jet expansions are weakly distorted by single coordination with surface dangling-oxygen atoms, on-the-fly trajectories indicate that the cluster skeletons undergo large-amplitude low-frequency vibrations. Local HX solvation, the extent of proton sharing, and the HX vibrational spectra undergo serious modulation on a picosecond time scale.