用可见激光研究丙胺分子的多光子电离

Multiphoton lonization of Propylamine with Visible Lasers

本文在443nm、478nm和532nm处，获得了不同激光强度下丙胺分子多光子电离（MPI）飞行时间-质谱（TOF－MS）。在前两波长和532nm处，丙胺分子分别由双光子和三光子共振激发到里德堡态，激发态分子进一步吸收光子电离。在443nm处，母体离子中的剩余能量使得它全部经α-键断裂形成碎片离子CH2＝N＋H2；而在478nm处，可探测到少量的母体离子。在532nm处，受三光于共振激发速率的制约，只有在较高激光强度下才能探测到产物离子，这时，母体离子被继续激发，获得更多的能量，使得脱氢反应可以和α-键断裂相竞争，MPI－MS中没有出现母体离子，但出现了较强的脱氢碎片离子。

The time-of-flight (TOF) mass spectra(MS) of propylamine produced bymultiphoton ionization(MPI) are obtained at 443 nm, 478 nm and 532 nm with different laser intensities. Parent molecules are 2-photon (at 443 nm and 478 nm) or3-photon(at 532 nm) resonantly excited to Rydberg states, then excited molecules are ionized by further photon-absorption.All of the parent ions dissociate via α-bondcleavage at 443 nm,while a small part of them could be observedat 475 nm. Ion sighal could only be detected with higher laser intensity at 532 nm, so that parent ions are excited and higher excess energy makes the H-eliminationcouldcompete with α-bond cleavage.