University of Vienna, Faculty of Physics, VCQ Vienna, Austria.
J Am Soc Mass Spectrom. 2013 Apr;24(4):602-8. doi: 10.1007/s13361-012-0551-3. Epub 2013 Feb 27.
The volatilization and soft ionization of complex neutral macromolecules at low energies has remained an outstanding challenge for several decades. Most volatilization techniques in mass spectrometry produce ions already in the source and most of them lead to particle velocities in excess of several hundred meters per second. For many macromolecules, post-ionization is inefficient since electronic or optical excitations can be followed by competing non-ionizing internal conversion, electron recapture, or fragmentation processes. Here, we explore the laser-assisted volatilization of neutral perfluoroalkyl-functionalized tetraphenylporphyrins as well as their single-photon ionization using vacuum ultraviolet (VUV) light at 157 nm. A systematic investigation of the ionization curves allows us to determine the molecular velocity distribution and ionization cross sections. We demonstrate the detection of single photon ionized intact organic molecules in excess of 10 kDa from a slow molecular beam.
几十年来，复杂中性大分子在低能量下的挥发和软电离一直是一个突出的挑战。质谱中的大多数挥发技术在源中就已经产生了离子，而且大多数技术导致的粒子速度超过每秒几百米。对于许多大分子来说，后电离效率不高，因为电子或光激发后可能会发生竞争的非电离内转换、电子俘获或碎裂过程。在这里，我们探索了使用 157nm 的真空紫外 (VUV) 光辅助中性全氟烷基官能化四苯基卟啉的挥发及其单光子电离。对电离曲线的系统研究使我们能够确定分子速度分布和电离截面。我们证明了从缓慢的分子束中检测到超过 10kDa 的单光子电离完整有机分子。
