Vibrational Raman spectroscopy (VRS) has been extensively used in a wide variety of fields of chemical sciences, and has advantages in probing solid catalysts and reagents under working conditions, and in the low frequency region where M-O (M: metal) vibrations appear. Like other spectroscopies, conventional VRS has some drawbacks. In the fields of catalysis and solid and liquid materials, the drawbacks include (1) unwanted fluorescence background, (2) low detection sensitivity for reduced catalysts and at low loadings. These drawbacks can be overcome by UV Raman and resonance Raman (RR) spectroscopy. Additional information that can be obtained by UV Raman and RR includes detection of O-H vibrations and selective enhancement in intensity of a specific vibrational mode, e.g., (1) V=O or V-O stretch, (2) defect or V=O or V-O-S (S: support) mode that is enhanced. UV resonance Raman spectroscopy lab at Argonne has all the capabilities of UV and resonance Raman as well as conventional vis Raman. Laser system includes continuous and discrete wavelength-tunable lasers which span a wide deep-UV to near-IR region. A triple spectrometer allows to efficiently filter out unwanted Rayleigh and stray lights so that high-quality, high-resolution Raman and very low-frequency Raman spectra down to 5 cm-1 (= 0.15 THz, 0.6 meV) for Stokes and Anti-Stokes lines can be obtained. UV Raman and RR results are presented for silica-supported WW triple-bond dimers, silica-supported Cu dimers, alumina-supported VOx and K-doped MoOx catalysts as examples. In addition, low-temperature (down to 77K), low-frequency (down to 10 cm-1) Raman spectra will be presented for lead halide perovskite nanocrystal that is a photovoltaic and optoelectronic material. A combination of RR and resonant hard x-ray electronic Raman (inelastic) results, evidencing Co-O-Co bridging bonds for oxygen evolution CoOx catalyst will also be presented if time permits.

UV resonance Raman spectroscopy at Argonne: Capabilities and advantageous examples

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.