J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 18223 Prague 8, Czech Republic.
Institute of Chemical Technology and Wilhelm-Ostwald-Institute of Physical and Theoretical Chemistry, Linnestrasse 3, D-04103 Leipzig, Germany.
J Am Soc Mass Spectrom. 2023 May 3;34(5):878-892. doi: 10.1021/jasms.2c00357. Epub 2023 Apr 5.
Small ice particles play an important role in atmospheric and extraterrestrial chemistry. Circumplanetary ice particles that are encountered by space probes at hypervelocities play a critical role in the determination of surface and subsurface properties of their source bodies. Here we present an apparatus for the generation of low-intensity beams of single mass-selected charged ice particles under vacuum. They are produced via electrospray ionization of water at atmospheric pressure and undergo evaporative cooling when transferred to vacuum through an atmospheric vacuum interface. / selection is achieved through two subsequent quadrupole mass filters operated in the variable-frequency mode within a range of / values between 8 × 10 and 3 × 10. Velocity and charge of the selected particles are measured using a nondestructive single-pass image charge detector. From the known electrostatic acceleration potentials and settings of the quadrupoles the particle masses could be obtained and be accurately controlled. It has been shown that the droplets are frozen within the transit time of the apparatus such that ice particles are present after the quadrupole stages and finally detected. The demonstrated correspondence between particle mass and specific quadrupole potentials in this device allows preparation of beams of single particles with a repetition rate between 0.1 and 1 Hz with various diameter distributions from 50 to 1000 nm at 30-250 eV of kinetic energy per charge. This corresponds to velocities and particle masses quickly available between 600 m/s (80 nm) and 50 m/s (900 nm) and particle charge numbers (positive) between 10 and 10[], depending upon size.
小冰粒在大气和天体化学中起着重要作用。高速飞行的空间探测器遇到的环绕行星的冰粒在确定其母体的表面和次表面特性方面起着关键作用。本文介绍了一种在真空下产生低强度单质量选择带电冰粒束的装置。它们是通过大气压下水的电喷雾电离产生的，当通过大气压真空接口转移到真空中时，会经历蒸发冷却。/ 选择是通过两个随后的四极质量过滤器在 8×10 和 3×10 之间的 / 值范围内以可变频率模式操作来实现的。所选粒子的速度和电荷使用非破坏性单通图像电荷探测器进行测量。从已知的静电加速势和四极的设置中，可以获得粒子的质量，并进行精确控制。已经表明，液滴在仪器的传输时间内被冻结，因此在四极阶段之后存在冰粒，并最终被检测到。在该装置中，粒子质量与特定四极电位之间的显示对应关系允许以 0.1 至 1 Hz 的重复率制备具有各种直径分布的单粒子束，直径分布范围为 50 至 1000 nm，每电荷的动能为 30-250 eV。这对应于 600 m/s（80nm）至 50 m/s（900nm）之间的速度和粒子质量，以及 10 至 10[]之间的粒子电荷数（正），具体取决于尺寸。
