Soft‐ and reactive landing of mass‐selected ions is gaining attention as a promising approach for the precisely‐controlled preparation of materials on surfaces that are not amenable to deposition using conventional methods. A broad range of ionization sources and mass filters are available that make ion soft‐landing a versatile tool for surface modification using beams of hyperthermal (<100 eV) ions. The ability to select the mass‐to‐charge ratio of the ion, its kinetic energy and charge state, along with precise control of the size, shape, and position of the ion beam on the deposition target distinguishes ion soft landing from other surface modification techniques. Soft‐ and reactive landing have been used to prepare interfaces for practical applications as well as precisely‐defined model surfaces for fundamental investigations in chemistry, physics, and materials science. For instance, soft‐ and reactive landing have been applied to study the surface chemistry of ions isolated in the gas‐phase, prepare arrays of proteins for high‐throughput biological screening, produce novel carbon‐based and polymer materials, enrich the secondary structure of peptides and the chirality of organic molecules, immobilize electrochemically‐active proteins and organometallics on electrodes, create thin films of complex molecules, and immobilize catalytically active organometallics as well as ligated metal clusters. In addition, soft landing has enabled investigation of the size‐dependent behavior of bare metal clusters in the critical subnanometer size regime where chemical and physical properties do not scale predictably with size. The morphology, aggregation, and immobilization of larger bare metal nanoparticles, which are directly relevant to the design of catalysts as well as improved memory and electronic devices, have also been studied using ion soft landing. This review article begins in section 1 with a brief introduction to the existing applications of ion soft‐ and reactive landing. Section 2 provides an overview of the ionization sources and mass filters that have been used to date for soft landing of mass‐selected ions. A discussion of the competing processes that occur during ion deposition as well as the types of ions and surfaces that have been investigated follows in section 3. Section 4 discusses the physical phenomena that occur during and after ion soft landing, including retention and reduction of ionic charge along with factors that impact the efficiency of ion deposition. The influence of soft landing on the secondary structure and biological activity of complex ions is addressed in section 5. Lastly, an overview of the structure and mobility as well as the catalytic, optical, magnetic, and redox properties of bare ionic clusters and nanoparticles deposited onto surfaces is presented in section 6. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 35:439–479, 2016.

Phosphomolybdate functionalized graphene nanocomposite (PMo12‐GS) has been successfully formed on a glassy carbon electrode (GCE) for the detection of ascorbic acid (AA). The obtained PMo12‐GS modified GCE, was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy (SEM) and Fourier transform infrared (FT‐IR) spectroscopy and compared with GCE, GS modified GCE, and PMo12 modified GCE. It shows an increased current and a decrease in over‐potential of ∼210 mV. The amperometric signals are linearly proportional to the AA concentration in a wide concentration range from 1×10−6 M to 8×10−3 M, with a detection limit of 0.5×10−6 M. The PMo12‐GS modified electrode was employed for the determination of the AA level in vitamin C tablets, with recoveries between 96.3 and 100.8 %.

The design of functional interfaces is central to both fundamental and applied research in materials science and energy technology. We introduce a new, broadly applicable technique for the precisely controlled high‐throughput preparation of well‐defined interfaces containing polyatomic species ranging from small ions to nanocrystals and large protein complexes. The mass‐dispersive deposition of ions onto surfaces is achieved using a rotating‐wall mass analyzer, a compact device which enables the separation of ions using low voltages and has a theoretically unlimited mass range. We demonstrate an efficient deposition of singly charged Au144(SC4H9)60 ions (33.7 kDa), which opens up exciting opportunities for the structural characterization of nanocrystals and their assemblies using transmission electron microscopy. Our approach also enables the high‐throughput deposition of mass‐selected ions from multicomponent mixtures, which is of interest to the controlled preparation of surface gradients and rapid screening of molecules in mixtures for a specific property.

Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.