An in situ cell to study phase transitions in individual aerosol particles on a substrate using scanning transmission x-ray microspectroscopy

Abstract

A new in situ cell to study phase transitions and chemical processes on individual aerosol particles in the x-ray transmission microscope at the PolLux beamline of the Swiss light source has been built. The cell is machined from stainless steel and aluminum components and is designed to be used in the standard mount of the microscope without need of complicated rearrangements of the microscope. The cell consists of two parts, a back part which contains connections for the gas supply, heating, cooling devices, and temperature measurement. The second part is a removable clip, which hosts the sample. This clip can be easily exchanged and brought into a sampling unit for aerosol particles. Currently, the cell can be operated at temperatures ranging from Ϫ40 to +50°C. The function of the cell is demonstrated using two systems of submicron size: inorganic sodium bromide aerosols and soot originating from a diesel passenger car. For the sodium bromide we demonstrate how phase transitions can be studied in these systems and that O1s spectra from aqueous sodium bromide solution can be taken from submicron sized particles. For the case of soot, we demonstrate that the uptake of water onto individual soot particles can be studied.

Aging induced changes on NEXAFS fingerprints in individual combustion particles

“…Exposure of the sample to various relative humidity and temperature environments during X-ray measurements in the PolLux microscope was enabled by a custom microreactor (see Huthwelker et al (2010) for a detailed description). Briefly, the microreactor consists of two parts: the sample substrate membrane, where the submicron particles are deposited and the body of the microreactor, which includes a capping membrane and a gas flow inlet and outlet.…”

“…The calibration of the spectra was performed by measuring the welldefined transitions of polystyrene spheres at the carbon edge (Dhez et al, 2003). All soot samples were measured in the microreactor (Zelenay et al, 2011a;Huthwelker et al, 2010).…”

“…In STXM, near edge X-ray absorption fine structure (NEXAFS) spectroscopy at the carbon edge allows obtaining spatially resolved carbon functional group composition of atmospheric particles (Russell et al, 2002). The novel aspect here is that this technique is applied to smog chamber samples enclosed within a microreactor to allow investigating water uptake to the particles at the oxygen edge in situ in parallel (Zelenay et al, 2011a;Huthwelker et al, 2010).…”

In Situ Synchrotron Radiation X‐Ray Microspectroscopy of Polymer Microcontainers

“…Based on the concept of two Si 3 N 4 windows that retain the sample, similar in situ cells have been used for studies using soft X-rays. That is, a real-space determination of the charge state in stimulus-responsive poly(4-vinylpyridine)/silica nanocomposite microgels [30] and poly(2-vinylpyridine) latex/microgel particles, [31] electrochemical study of the galvanic coupling of Au and Fe in different solutions, [32] phase transitions in individual aerosol particles, [33] and characterization of groundwater colloids. [34] 4.…”

A NeXus/HDF5 based file format for STXM

“…[14] The sample mounting in STXMs also tend to be quite accessible and numerous examples exist of environmental cells and in-situ operation of technological devices. [15,16,17,18,19,20,21] The many combinations of contrast mechanisms, detection schemes, scanning modes/patterns and sample configurations demonstrate the enormous range of STXM experiments.…”