Laboratoire de Chimie Physique Moléculaire (LCPM), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
J Chem Phys. 2012 Jun 28;136(24):244308. doi: 10.1063/1.4730295.
Quantum beat spectroscopy is combined with triple-resonance vibrational overtone excitation to measure the Stark coefficients (SCs) of the water molecule for 28 rovibrational levels lying from 27,600 to 41,000 cm(-1). These data provide a stringent test for assessing the accuracy of the available potential energy surfaces (PESs) and dipole moment surfaces (DMSs) of this benchmark molecule in this energy region, which is inaccessible by direct absorption. SCs, calculated using the combination of a high accuracy, spectroscopically determined PES and a recent ab initio DMS, are within the 1% accuracy of available experimental data for levels below 25,000 cm(-1), and within 4.5% for coefficients associated with levels up to 35,000 cm(-1). However, the error in the computed coefficients is over 60% for the very high rovibrational states lying just below the lowest dissociation threshold, due, it seems, to lack of a high accuracy PES in this region. The comparative analysis suggests further steps, which may bring the theoretical predictions closer to the experimental accuracy.
量子拍频光谱学与三共振振动泛频激发相结合，测量了 27600 到 41000cm(-1) 之间的 28 个转动-振动能级的水分子的斯塔克系数 (SCs)。这些数据为评估该基准分子在该能量区域内可用的势能面 (PESs) 和偶极矩面 (DMSs) 的准确性提供了严格的测试，而直接吸收无法达到该能量区域。使用高精度、光谱确定的 PES 和最近的从头算 DMS 组合计算的 SCs，对于低于 25000cm(-1) 的能级，与可用实验数据的精度在 1%以内，对于与能级高达 35000cm(-1) 的系数，精度在 4.5%以内。然而，对于位于最低离解阈值以下的非常高的转动-振动态，计算出的系数误差超过 60%，这似乎是由于该区域缺乏高精度的 PES。比较分析表明还需要采取进一步的步骤，以使理论预测更接近实验精度。
