Vibrational predissociation of the phenol–water dimer: a view from the water
Vibrational predissociation of the phenol–water dimer: a view from the water
复制标题
苯酚-水二聚体的振动预解离：从水中观察
DOI：
10.1039/c8cp06581k
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发表时间：
2019
影响因子：
3.3
通讯作者：
Reisler, Hanna
中科院分区：
文献类型：
--
作者：
Kwasniewski, Daniel;Butler, Mitchell;Reisler, Hanna
研究了苯酚-水（PhOH-H2O）二聚体的振动预解离（VP）动力学，通过检测H2O碎片并利用速度图成像（VMI）来推断PhOH共碎片的内能分布，与H2O碎片的选定转动能级对相关.在红外（IR）激光激发的氢键OH拉伸基本的PhOH（途径1）或不对称的OH拉伸定位在H2O（途径2），解离H2O + PhOH观察。采用2+1共振增强多光子电离（REMPI）结合飞行时间质谱（TOF-MS）对H2O碎片进行了状态选择性监测。在选定的旋转水平下的H2O的VMI用于导出质心（c.m.）平移能量（ET）分布。通过途径1衍生的PhOH共片段的对相关的内部能量分布很好地描述了统计先验分布。另一方面，通过途径2获得的相应分布显示出比从统计分布预期的更高能量的PhOH振转能级的倾向，并且与能隙模型更好地一致。两种途径的H2O碎片的REMPI光谱可以通过在最大允许能量处截断的Boltzmann图拟合，其中途径2的温度高于途径1的温度。我们的结论是VP动力学依赖于OH拉伸水平最初激发。
The vibrational predissociation (VP) dynamics of the phenol–water (PhOH–H2O) dimer were studied by detecting H2O fragments and using velocity map imaging (VMI) to infer the internal energy distributions of PhOH cofragments, pair-correlated with selected rotational levels of the H2O fragments. Following infrared (IR) laser excitation of the hydrogen-bonded OH stretch fundamental of PhOH (Pathway 1) or the asymmetric OH stretch localized on H2O (Pathway 2), dissociation to H2O + PhOH was observed. H2O fragments were monitored state-selectively by using 2+1 Resonance-Enhanced Multiphoton Ionization (REMPI) combined with time-of-flight mass spectrometry (TOF-MS). VMI of H2O in selected rotational levels was used to derive center-of-mass (c.m.) translational energy (ET) distributions. The pair-correlated internal energy distributions of the PhOH cofragments derived via Pathway 1 were well described by a statistical prior distribution. On the other hand, the corresponding distributions obtained via Pathway 2 show a propensity to populate higher-energy rovibrational levels of PhOH than expected from a statistical distribution and agree better with an energy-gap model. The REMPI spectra of the H2O fragments from both pathways could be fit by Boltzmann plots truncated at the maximum allowed energy, with a higher temperature for Pathway 2 than that for Pathway 1. We conclude that the VP dynamics depends on the OH stretch level initially excited.