Observation of Rainbows in the Rotationally Inelastic Scattering of NO with CH4.
Observation of Rainbows in the Rotationally Inelastic Scattering of NO with CH4.
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NO 与 CH4 旋转非弹性散射中彩虹的观察。
DOI：
10.1021/acs.jpca.9b06806
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Wang XD
中科院分区：
文献类型：
--
作者：
Wang XD
利用速度图成像和共振增强多光子电离探测与交叉分子束散射相结合的方法，研究了在平均碰撞能量为70 0 cm-1的CH4碰撞中NO的转动能量转移动力学。NO散射到单个转动(JNO‘)能级和自旋轨道(Ω)能级的图像通常显示出一个单一的宽峰值，随着转动激发的增加(即较大的ΔJNO)，该峰值逐渐从前向后向散射方向移动。用二维硬椭圆模型计算的旋转彩虹角与从Δ较高的jNO跃迁图像中提取的微分截面的最大值对应的观测角度符合得很好，但对于较低的ΔjNO则有明显的差异(特别是当jNO‘=7.5时的最终转动能级)。这些低ΔjNO型跃迁的急剧前向散射角分布与L彩虹模型的预测更符合。NO的高转动激发似乎与副产物CH4的低转动激发相一致，这表明在这种双分子散射中存在一定程度的旋转积对反相关。
Using a combination of velocity-map imaging and resonance-enhanced multiphoton ionization detection with crossed molecular beam scattering, the dynamics of rotational energy transfer have been examined for NO in collisions with CH4at a mean collision energy of 700 cm–1. The images of NO scattered into individual rotational (jNO′) and spin–orbit (Ω) levels typically exhibit a single broad maximum that gradually shifts from the forward to the backward scattering direction with increasing rotational excitation (i.e., larger ΔjNO). The rotational rainbow angles calculated with a two-dimensional hard ellipse model show reasonable agreement with the observed angles corresponding to the maxima in the differential cross sections extracted from the images for higher ΔjNOtransitions, but there are clear discrepancies for lower ΔjNO(in particular, final rotational levels withjNO′= 7.5 and 8.5). The sharply forward scattered angular distributions for these lower ΔjNOtransitions better agree with the predictions of an L-type rainbow model. The more highly rotationally excited NO appears to coincide with low rotational excitation of the co-product CH4, indicating a degree of rotational product–pair anticorrelation in this bimolecular scattering.