Direct Measurement of the Angular Dependence of the Single-Photon Ionization of Aligned N2 and CO2

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• 作者：Isabell Thomann ; Robynne Lock ; Vandana Sharma ; Etienne Gagnon ; Stephen T. Pratt ; Henry C. Kapteyn ; Margaret M. Murnane ; Wen Li
• 刊名：Journal of Physical Chemistry A
• 出版年：2008
• 出版时间：October 2, 2008
• 年：2008
• 卷：112
• 期：39
• 页码：9382-9386
• 全文大小：311K
• 年卷期：v.112,no.39(October 2, 2008)
• ISSN：1520-5215

文摘

By combining a state-of-the-art high-harmonic ultrafast soft X-ray source with field-free dynamic alignment, we map the angular dependence of molecular photoionization yields for the first time for a nondissociative molecule. The observed modulation in ion yield as a function of molecular alignment is attributed to the molecular frame transition dipole moment of single-photon ionization to the X, A and B states of N₂⁺ and CO₂⁺. Our data show that the transition dipoles for single-photon ionization of N₂ and CO₂ at 43 eV have larger perpendicular components than parallel ones. A direct comparison with published theoretical partial wave ionization cross-sections confirms these experimental observations, which are the first results to allow such comparison with theory for bound cation states. The results provide the first step toward a novel method for measuring molecular frame transition dipole matrix elements.