A new ion mobility (IM) spectrometer, enabling mobility measurements in the pressure range between 5 and 500 mbar and in the reduced field strength range E/N of 5–90 Td, was developed and characterized. Reduced mobility (K₀) values were studied under low E/N (constant value) as well as high E/N (deviation from low field K₀) for a series of molecular ions in nitrogen. Infrared matrix-assisted laser desorption ionization (IR-MALDI) was used in two configurations: a source working at atmospheric pressure (AP) and, for the first time, an IR-MALDI source working with a liquid (aqueous) matrix at sub-ambient/reduced pressure (RP). The influence of RP on IR-MALDI was examined and new insights into the dispersion process were gained. This enabled the optimization of the IM spectrometer for best analytical performance. While ion desolvation is less efficient at RP, the transport of ions is more efficient, leading to intensity enhancement and an increased number of oligomer ions. When deciding between AP and RP IR-MALDI, a trade-off between intensity and resolving power has to be considered. Here, the low field mobility of peptide ions was first measured and compared with reference values from ESI-IM spectrometry (at AP) as well as collision cross sections obtained from molecular dynamics simulations. The second application was the determination of the reduced mobility of various substituted ammonium ions as a function of E/N in nitrogen. The mobility is constant up to a threshold at high E/N. Beyond this threshold, mobility increases were observed. This behavior can be explained by the loss of hydrated water molecules.

开发并表征了一种新型的离子迁移率（IM）光谱仪，可以在5到500 mbar的压力范围内以及在降低的场强范围E / N为5–90 Td的范围内进行迁移率测量。在低E / N（恒定值）以及高E / N（偏离低场K _0的情况下）研究了降低的迁移率（K ₀）值）中的一系列分子离子。红外基质辅助激光解吸电离（IR-MALDI）有两种配置：一种是在大气压（AP）下工作的离子源，另一种是IR-MALDI在低于环境/减压（RP）。考察了RP对IR-MALDI的影响，并获得了对分散过程的新见解。这样就可以优化IM光谱仪以获得最佳分析性能。尽管离子去溶剂化在RP时效率较低，但离子的运输效率更高，从而导致强度增强和低聚物离子数量增加。在AP和RP IR-MALDI之间进行选择时，必须考虑强度和分辨能力之间的权衡。这里，首先测量了肽离子的低场迁移率，并将其与ESI-IM光谱法（在AP处）的参考值以及从分子动力学模拟获得的碰撞截面进行了比较。第二项应用是确定各种取代铵离子的迁移率降低与氮中的E / N。在高E / N下，迁移率恒定到阈值。超过该阈值，观察到流动性增加。这种现象可以用失水的水分子来解释。