Droplet-based in situ X-ray absorption spectroscopy cell for studying crystallization processes at the tender X-ray energy range

Abstract

We introduce a new in situ cell for time-resolved reactions involving aerosols/droplets using tender X-ray absorption spectroscopy and related methods.

The Crystallization Process of Vaterite Microdisc Mesocrystals via Proto-Vaterite Amorphous Calcium Carbonate Characterized by Cryo-X-ray Absorption Spectroscopy

“…A post edge feature appears at 4061 eV. The absorption edges of Ca of the samples with different crystallization times generally shift to low photoelectron energy, from 4052.90 to 4052.29 eV, while increasing the crystallization times from 0.5 to 20 d, indicating the increase of crystallinity degree of calcium carbonate [27]. In comparison, the absorption edge of vaterite reference is at 4051.5 eV.…”

“…Besides the classical theory of nucleation and crystallization based on atoms, ions and small molecules, non-classical nucleation and crystallization mechanism was proposed as a complementary novel crystallization mechanism which uses amorphous intermediate precursors such as droplets, clusters, or oligomers as intermediate phases or precursors of crystallization [25,26]. It is still a challenge to elucidate how intermediate precursors in solutions convert to different crystalline phases through multiple phase transformations [27]. A lot of studies have focused on the crystallization mechanisms by using anhydrous calcium carbonate forms such as calcite and aragonite as crystallization models while the formation of the thermodynamically least stable vaterite is less known.…”

“…A lot of studies have focused on the crystallization mechanisms by using anhydrous calcium carbonate forms such as calcite and aragonite as crystallization models while the formation of the thermodynamically least stable vaterite is less known. Solid state transformation from ACC to vaterite was observed by using Cryo-transmission electron microscopy (TEM) [28] and synchrotron-based in situ time-resolved energy dispersive X-ray diffraction (ED-XRD) [29] and X-ray absorption spectroscopy (XAS) [27,30].…”

“…XAS analysis provides high resolution structural information on the local atomic environment, the nearest neighbor shells around a metal ion of interest [31]. XAS has been applied to study the formation processs of biogenic and synthetic calcium carbonates [7,27,30,32]. XAS characterization of ACC deposited in crustacea Porcellio scaber showed short-range order which is comparable to crystalline calcium carbonate phases [32].…”

“…Gebauer and coworkers applied XAS to distinguish synthetic additive-free proto-calcite ACC and proto-vaterite ACC which have different short-range ordered structures [7]. The intermediate phases involved during calcium carbonate crystallization from aqueous solutions were captured by using in situ XAS [27].…”