High Resolution Multimodal Chemical Imaging Platform for Organics and Inorganics

Abstract

Chemical analysis at the nanoscale is critical to advance our understanding of materials and systems from medicine and biology to material science and computing. Macroscale-observed phenomena in these systems are in the large part driven by processes that take place at the nanoscale and are highly heterogeneous. Therefore, there is a clear need to develop a new technology that enables correlative imaging of material functionalities with nanoscale spatial and chemical resolutions that will enable us to untangle the structure−function relationship of functional materials. Therefore, here, we report on the analytical figures of merit of the newly developed correlative chemical imaging technique of helium ion microscopy coupled with secondary ion mass spectrometry (HIM-SIMS) that enables multimodal topographical/chemical imaging of organic and inorganic materials at the nanoscale. In HIM-SIMS, a focused ion beam acts as a sputtering and ionization source for chemical analysis along with simultaneous high-resolution surface imaging, providing an unprecedented level of spatial resolution for gathering chemical information on organic and inorganic materials. In this work, we demonstrate HIM-SIMS as a platform for a next-generation tool for an in situ material design and analysis capable of down to 8 nm spatial resolution chemical imaging, layered metal structure imaging in depth profiling, single graphene layer detection, and spectral analysis of metals, metal oxides, and polymers.

Summary of ISO/TC 201 International Standard ISO 18516:2019 Surface chemical analysis—Determination of lateral resolution and sharpness in beam‐based methods with a range from nanometres to micrometres and its implementation for imaging laboratory X‐ray photoelectron spectrometers (XPS)

“…4 The dimensions of the narrow lines and the A-B-A gratings are all in the submicrometre range. Most applications of BAM L200 are seen for the use of the grating method for a determination of lateral resolution in nanoscale imaging by SIMS (cf., e.g., references 4,[7][8][9][10][11][12][13][14][15] and AES (cf., e.g., references 4,[16][17][18][19] ). For XPS, there are only some implementations of the grating method using NanoESCA instruments (Omicron Nanotechnology) working as experimental end stations at synchrotron radiation sources.…”

Obtaining molecular imagings of pesticide residues on strawberry surfaces with probe sampling followed by ambient ionization mass spectrometric analysis

“…MSI's two most commonly used ionization methods are matrix-assisted laser desorption/ionization (MALDI) and secondary ionization mass spectrometry (SIMS). [6][7][8] SIMS can detect organic and inorganic compounds under a very high spatial resolution (sub-micrometer), but the masses of the detectable molecules or elements are relatively low, 9 whereas MALDI can detect large biological molecules and is the most commonly used ionization method for MSI but has a low spatial resolution (10-50 μm). MALDI-MSI is performed in microprobe mode in a vacuum, and thus, the signals of the molecules in each laser desorption spot are recorded individually.…”

“…Recently, the development of the combination of thermal desorption-electrospray ionization mass spectrometry (TD-ESI/MS) with a probe allows for direct surface sample analysis without sample preparation. 1,[7][8][9][10] Analytes, such as pesticides on fruit surfaces, are collected simply by sweeping a metallic probe along the fruit's surface for approximately 1 cm. The probe is then inserted in a thermal desorption unit to desorb the analytes on the probe's tip, with a nitrogen gas stream subsequently delivering the desorbed analytes to an electrospray plume that was generated from a methanol solution flowing out of a capillary.…”

“…Recently, the development of the combination of thermal desorption‐electrospray ionization mass spectrometry (TD‐ESI/MS) with a probe allows for direct surface sample analysis without sample preparation 1,7–10 . Analytes, such as pesticides on fruit surfaces, are collected simply by sweeping a metallic probe along the fruit's surface for approximately 1 cm.…”

Helium Ion Microscopy with Secondary Ion Mass Spectrometry (HIM-SIMS) for the analysis and quantitation of polyolefins

“…[22][23][24] The implementation of SIMS on the HIM offers the additional benefit of performing multimodal chemical imaging, where the He + and Ne + beams can be used for both high resolution iSE imaging with down to 0.5 nm resolution as well as sputtering of the surface to generate secondary ions for SIMS detection. [24][25][26][27] Therefore, the HIM-SIMS offers the opportunity for insitu correlative imaging combining ultrahigh resolution iSE images with elemental/chemical maps from SIMS. Consequently, the combination of the high-resolution imaging and the chemical sensitivity for the detection of the ion distribution with a lateral resolution of tens of nanometers has been used for the analysis of organic and inorganic systems including chemical segregation of ionic species in hybrid organic inorganic perovskites (HOIPs), 28,29 impurities in devices, 30 trace element analysis in biological systems.…”