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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Multiply Charged lons from Armatic Molecules Following lrradiation in Intense Laser Fields
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Multiply Charged lons from Armatic Molecules Following lrradiation in Intense Laser Fields

机译：在强激光场中辐照后，来自芳香分子的带电离子倍增

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摘要

It is well-known that aromatic molecules,when irradiated by UV laser beams in the nanosecond pulse width regime, yield exclusive parent ions at laser intensities of 107 W cm~-2 (soft ionizatiohn).As the laser intensities increase up to 10~9 W cm~-2, however, extensive fragmentation takes place such that small mass fragments dominate the spectra at the expense of parent signature ions. The reason for this is that the dissociative lifetimes are shorter than the laser pulse width and ladder-switching fragmentation takes place. With the development of high power femtosecond lasers, these dissociative lifetimes can often be bypassed. Presently, at laser intensities up the order of 10~-15 W cm~-2 with pulse widths as short as 50 fs at near-infrared (IR) wavelengths (790 nm), soft ionization again takes place. This has been using a technique known as femmtosecond laser mass spectrometry (FLMS). Under such conditions, stable multiply charged parent and adjacent satellite ions are observed and the fragmentation ions minimal. In this paper, these effects are described for the medium-mass aromatic molecules benzene, monodeuterated benzene, toluene, and naphthalene. Other studies have shown that for diatomic and triatomic ions, the absorption of many photons produces transient multicharged atomic species. This so-called "Coulomb explosion" model to explain the results which are presented here, at the above-mentioned beam intensities. In contrast, the polyatomic molecules studied presently using IR FLMS display atomic-like characteristics.
机译：众所周知，当芳香族分子在纳秒脉冲宽度范围内被紫外线激光束照射时，会在107 W cm〜-2的激光强度下产生唯一的母离子（软电离）。随着激光强度增加到10〜然而，在9 W cm〜-2时，发生了广泛的碎裂，使得小质量碎片占据了光谱的大部分，而以母体特征离子为代价。其原因是，解离寿命短于激光脉冲宽度，并且发生了梯形开关碎裂。随着高功率飞秒激光器的发展，这些分离寿命通常可以绕开。目前，在近红外（IR）波长（790 nm）处脉冲宽度短至50 fs的激光强度达到10〜-15 W cm〜-2量级时，再次发生软电离。这一直使用一种称为飞秒激光质谱（FLMS）的技术。在这种条件下，观察到稳定的多电荷母体和邻近卫星离子，碎片离子极少。在本文中，描述了中等质量芳族分子苯，单氘代苯，甲苯和萘的这些作用。其他研究表明，对于双原子和三原子离子，许多光子的吸收会产生瞬态的多电荷原子。这种所谓的“库仑爆炸”模型用于解释在上述光束强度下此处给出的结果。相反，目前使用IR FLMS研究的多原子分子显示出类似原子的特性。

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