Toshiaki Ando, Akihiro Shimamoto, Shun Miura, Atsushi Iwasaki, Katsunori Nakai & Kaoru Yamanouchi

doi:10.1038/s42004-017-0006-7

化学物理；反应动力学与动力学

Published:

08 March 2018

When hydrocarbon molecules are exposed to an intense laser field, triatomic hydrogen molecular ion, H3+, is ejected. Here we describe pump–probe measurements of the ejection of H3+ from methanol dication with high temporal resolution using intense few-cycle laser pulses and find a long-lasting periodic increase in the yield of H3+. We show that H3+ ejection is the lowest energy decomposition channel and that its yield is enhanced each time when the vibrational wave packet coming back to the inner turning point of methanol cation is projected onto the dication potential energy surface. We also show that the time-resolved measurement of the yield of H3+ is an efficient tool not only for probing ultrafast nuclear dynamics of hydrocarbon cations but also for deriving vibrational frequencies of hydrocarbon cations with high precision.

今年三月份《通讯-化学》发表的一项研究Coherent vibrations in methanol cation probed by periodic H3+ ejection after double ionization报道了一种探测甲醇阳离子中的相干振动的方法，为空间甲醇阳离子研究提供了新的理论工具。

当碳氢化合物分子暴露在强烈的激光场中时，会释放出三原子氢分子离子H3+。来自日本东京大学的Kaoru Yamanouchi及同事们用高强度少周期的激光脉冲去激发甲醇双阳离子，然后利用泵浦-探测方法来检测释放出的H3+离子，检测结果有很高的时间分辨率，并且他们发现H3+的产量呈周期性增长趋势。作者发现H3+喷射是最低的能量分解通道，每当返回到甲醇阳离子内转折点的振动波包被投射到阳离子势能面时，H3+的喷射量都会相应增加。

该研究表明，H3+的时间分辨率测量法不仅是探测碳氢阳离子超快核动力学的有效工具，而且也是高精度地推导碳氢阳离子振动频率的有效工具。（来源：科学网）