Photophysical Studies of Formic Acid in the Vacuum UV: Fragmentation, Fluorescence, and Ionization in the 6−23 eV Photon Energy Range†
Photophysical Studies of Formic Acid in the Vacuum UV: Fragmentation, Fluorescence, and Ionization in the 6−23 eV Photon Energy Range†
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DOI：
10.1021/jp020809t
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发表时间：
2002-10
影响因子：
2.9
通讯作者：
M. Schwell;F. Dulieu;H. Jochims;J. Fillion;J. Lemaire;A. Baumgärtel;S. Leach
中科院分区：
文献类型：
--
作者：
M. Schwell;F. Dulieu;H. Jochims;J. Fillion;J. Lemaire;A. Baumgärtel;S. Leach
在6−23 eV范围内，利用光碎片荧光光谱和同步辐射激发研究了气态甲酸（HCOOH）的真空紫外（VUV）光解离。以前的研究仅限于11.4 eV以下的区域。在真空紫外中，在不同的激发能量下观察到OH（A），CH（A，B），HCOO和H Balmer辐射的发射。相应的荧光激发光谱中的谱带可以与HCOOH的特定吸收带相关联。HCOO在330 ~ 480 nm之间的荧光归属于2B 1 → 2A "跃迁。光电离的量子产额γ，从10到23 eV测量，在18 ± 0.1 eV处达到1。在电离阈值以上，超激发态的竞争非离子衰变过程的能域ΔE为ΔE（HCOOH）= 6.68 ± 0.1eV。在15.7 - 17 eV之间，会聚到HCOOH+32A'态的里德伯吸收带在γ（Eexc）谱中得到反映，由此得到自电离速率kai = 7.5 × 10 ~（13）s ~（-1）。
Vacuum-UV (VUV) photodissociation of gaseous formic acid (HCOOH) has been studied in the 6−23 eV range using photofragment fluorescence spectroscopy and synchrotron radiation excitation. Previous studies were limited to the region below 11.4 eV. Emission of OH (A), CH (A, B), HCOO, and H Balmer radiation is observed at various excitation energies in the VUV. Bands in the corresponding fluorescence excitation spectra can be associated with specific absorption bands of HCOOH. The HCOO fluorescence between 330 and 480 nm is assigned to the 2B1 → 2A‘ ‘ transition. The quantum yield of photoionization, γ, measured from 10 to 23 eV, reaches unity at 18 ± 0.1 eV. The energy domain, ΔE, of competitive nonionic decay processes of superexcited molecular states above the ionization threshold is thus found to be ΔE(HCOOH) = 6.68 ± 0.1 eV. Between 15.7 and 17 eV, Rydberg absorption bands converging to the 32A‘ state of HCOOH+ are mirrored in the γ(Eexc) spectrum, from which an autoionization rate kai ≈ 7.5 × 1013 s-1 ...