Carbon 1s photoelectron spectrum of methane: Vibrational excitation and core-hole lifetime
Carbon 1s photoelectron spectrum of methane: Vibrational excitation and core-hole lifetime
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甲烷的碳 1s 光电子能谱：振动激发和芯孔寿命
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
T. Thomas
中科院分区：
文献类型：
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作者：
T. Carroll;N. Berrah;J. Bozek;J. Hahne;E. Kukk;L. J. Sæthre;T. Thomas
测量了CH{sub 4}在302、320和330 eV光子能量下和CD{sub 4}在330 eV光子能量下的碳1 s光电子能谱，仪器分辨率约为自然线宽的一半。这些光谱已被分析，以获得振动间距，振动强度，和寿命的碳1 s的核心空穴状态。振动强度随光子能量的变化而变化，与早期的结果一致。在330 eV，观察到的弗兰克-康登因子CH{sub 4}和CD{sub 4}可以理解，只有当非谐波效应（与理论的预测一致）包括在内。另一方面，CH{sub 4}中的振动间距没有显示出非谐性的证据（与理论预测相反）。在CD{sub 4}中，观察到的振动能间距的非谐性约为预测值的一半，但实验值和理论值的差异仅与实验不确定性相当。寿命的测量值显示依赖于光子能量，这是由于碰撞后相互作用的理论，以正确地预测所观察到的电子光谱阈值附近的失败。在330 eV处，测得的洛伦兹寿命为93 - 95 meV，与简单理论的预测一致，但与更完整理论的预测不一致。它也被观察到，有系统的观测到的线的形状和碰撞后相互作用理论的预测之间的差异。{copyright} {ital 1999} {ital The American Physical Society}«收起
The carbon 1s photoelectron spectrum has been measured for CH{sub 4} at photon energies of 302, 320, and 330 eV and for CD{sub 4} at 330 eV with an instrumental resolution about half the natural linewidth. These spectra have been analyzed to obtain vibrational spacings, vibrational intensities, and the lifetime of the carbon 1s core-hole state. The vibrational intensities vary with photon energy, in agreement with earlier results. At 330 eV, the observed Franck-Condon factors for both CH{sub 4} and CD{sub 4} can be understood only if anharmonic effects (consistent with the predictions of theory) are included. On the other hand, the vibrational spacings in CH{sub 4} show no evidence for anharmonicity (in contrast with theoretical predictions). In CD{sub 4} the observed anharmonicity in the vibrational energy spacings is about half of the predicted value, but the experimental and theoretical values differ only by an amount comparable to the experimental uncertainty. The measured values of the lifetime show a dependence on photon energy; this is attributed to failure of the theory of post-collision interaction to predict correctly the observed electron spectrum near threshold. At 330 eV, the measured Lorentzian lifetime, 93{endash}95 meV, agrees with predictions of simple theory, but notmore » with the prediction of more complete theory. It is also observed that there are systematic discrepancies between the observed line shapes and those predicted by the theory of postcollision interaction. {copyright} {ital 1999} {ital The American Physical Society}« less