Department of Chemistry, Indiana University, 800 E. Kirkwood Ave., Bloomington, Indiana 47405, USA.
J Chem Phys. 2010 Jun 28;132(24):244301. doi: 10.1063/1.3430525.
We investigate and analyze the vibrational properties, including hydrogen/deuterium isotope effects, in a fundamental organic hydrogen bonded system using multiple experimental (infrared multiple photon dissociation and argon-tagged action spectroscopy) and computational techniques. We note a qualitative difference between the two experimental results discussed here and employ ab initio molecular dynamics simulations to explain these results. A deeper understanding of the differences between the isotopically labeled systems arises from an analysis of the simulated cluster spectroscopy and leads to a system-bath coupling interpretation. Specifically, when a few active modes, involving the shared hydrogen/deuterium stretch, are identified and labeled as "system," with all other molecular vibrational modes being identified as "bath" modes, we find critical differences in the coupling between the system modes for the shared proton and shared deuteron cases. These differences affect the energy repartitioning between these modes resulting in a complex spectral evolution as a function of temperature. Furthermore, intensity borrowing across modes that are widely distributed in the frequency domain plays an important role on the simulated spectra.
我们使用多种实验（红外多光子解离和氩标记动作光谱）和计算技术研究和分析了基本有机氢键体系的振动特性，包括氢/氘同位素效应。我们注意到这里讨论的两个实验结果之间存在定性差异，并采用从头算分子动力学模拟来解释这些结果。通过对模拟簇光谱的分析，可以更深入地了解同位素标记体系之间的差异，并得出体系-浴耦合解释。具体来说，当确定并标记几个涉及共享氢/氘伸缩的活跃模式为“体系”，并将所有其他分子振动模式识别为“浴”模式时，我们发现共享质子和共享氘核情况下体系模式之间的耦合存在关键差异。这些差异影响了这些模式之间的能量分配，导致作为温度函数的复杂光谱演化。此外，在频率域中广泛分布的模式之间的强度借用在模拟光谱中起着重要作用。
