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Microfluidic reactors with in situ spectroscopy have enabled many new directions of research over the last two decades. The miniature nature of these systems enables several key advantages in heterogeneous catalysis, which includes the reaction surface or interface accessible to spectroscopic equipment making the discovery of new catalytic materials possible. Devices fabricated with materials that are transparent to electromagnetic radiation enable in situ and in operando spectroscopy such as Raman, UV-Vis, and IR directly at the point of the reaction, and thus high fidelity, transient information on the reaction chemistry is available. Innovative designs with NMR, electrochemical impedance spectroscopy, x-ray techniques, or terahertz imaging have also advanced the field of heterogeneous catalysis. These methods have been successfully engineered to make major breakthroughs in the design of catalytic materials for important classes of chemical reactions. In this review, the authors provide an overview of recent advances in the design of microreactors with in situ spectroscopy for the study of heterogeneous catalysis to raise awareness among the vacuum science community on techniques, tools, existing challenges, and emerging trends and opportunities.
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This content will become publicly available on January 1, 2026
Implementation of simultaneous ultraviolet/visible and x-ray absorption spectroscopy with microfluidics
X-ray spectroscopies are uniquely poised to describe the geometric and electronic structure of metalloenzyme active sites under a wide variety of sample conditions. UV/Vis (ultraviolet/visible) spectroscopy is a similarly well-established technique that can identify and quantify catalytic intermediates. The work described here reports the first simultaneous collection of full in situ UV/Vis and high-energy resolution fluorescence detected x-ray absorption spectra. Implementation of a fiber optic UV/Vis spectrometer and parabolic mirror setup inside the dual array valence emission spectrometer allowing for simultaneous measurement of microfluidic flow and mixing samples at the Photon-In Photon-Out X-ray Spectroscopy beamline is described, and initial results on ferricyanide and a dilute iron protein are presented. In conjunction with advanced microfluidic mixing techniques, this will allow for the measurement and quantification of highly reactive catalytic intermediates at reaction-relevant temperatures on the millisecond timescale while avoiding potential complications induced by freeze quenching samples.
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- Award ID(s):
- 1231306
- PAR ID:
- 10588808
- Publisher / Repository:
- Review of Scientific Instruments
- Date Published:
- Journal Name:
- Review of Scientific Instruments
- Volume:
- 96
- Issue:
- 1
- ISSN:
- 0034-6748
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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