Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA.
J Phys Chem A. 2009 Dec 31;113(52):14206-11. doi: 10.1021/jp9008338.
Mass-analyzed threshold ionization (MATI) spectroscopy using synchrotron radiation (Advanced Light Source, Lawrence Berkeley National Laboratory) has been performed for Ar, N(2), O(2), N(2)O, H(2)O, C(2)H(2), and C(6)H(6). MATI allows for a better determination of ionization energies compared to those derived from photoionization efficiency curves traditionally used in synchrotron photoionization mass spectrometry. The separation of the long-lived Rydberg state from the directly formed prompt ion, essential for a meaningful MATI spectrum, has been accomplished by employing an arrangement of ion optics coupled to unique electric field pulsing schemes. For Ar, a number of resolved bands below the ionization energy are observed, and these are ascribed to high-n,l Rydberg states prepared in the MATI scheme. The first vibrational state resolved MATI spectra of N(2) and O(2) are reported, and spectral characteristics are discussed in comparison with previously reported threshold photoelectron spectroscopic studies. Although MATI performed with synchrotron radiation is intrinsically less sensitive compared to laser-based sources, this work demonstrates that MATI spectroscopy performed with widely tunable vacuum ultraviolet (VUV) radiation is a complementary technique for studying the ionization spectroscopy of polyatomic molecules.
采用同步辐射（劳伦斯伯克利国家实验室先进光源）进行了质量分析阈值电离 (MATI) 光谱学研究，涉及 Ar、N(2)、O(2)、N(2)O、H(2)O、C(2)H(2) 和 C(6)H(6)。与传统的同步光电离质谱中使用的光电离效率曲线得出的电离能相比，MATI 可以更好地确定电离能。通过采用与独特电场脉冲方案相结合的离子光学排列，实现了长寿命里德堡态与直接形成的瞬态离子的分离，这对于有意义的 MATI 光谱至关重要。对于 Ar，观察到低于电离能的许多分辨谱带，这些谱带归因于在 MATI 方案中制备的高 n，l 里德堡态。首次报道了 N(2)和 O(2)的第一振动态分辨 MATI 光谱，并与先前报道的阈值光电子光谱研究进行了比较讨论了光谱特征。尽管与基于激光的源相比，采用同步辐射的 MATI 固有地灵敏度较低，但这项工作表明，采用广泛可调谐真空紫外 (VUV) 辐射的 MATI 光谱学是研究多原子分子电离光谱学的一种互补技术。
