In situ diagnostics of catalytic materials using tunable confocal Raman spectroscopy

Abstract

A new Raman spectroscopic setup for in situ characterization of catalytic materials based on a tunable laser system and a confocal Raman microscope is described. The laser excitation wavelength is variable over a broad range from deep ultraviolet (UV) to near-infrared allowing for targeted use of Raman diagnostics for catalyst characterization. By utilization of resonance effects, the sensitivity of the method can be strongly increased. The potential of the setup is illustrated by new in situ Raman results on dispersed vanadium oxide catalysts obtained at 217.5 and 280 nm UV laser excitation.

UV Raman spectroscopy of segregated carbon in silicon oxycarbides

“…For a more detailed description of the laser assembly and the spectrometer, the reader is referred to Ref. 28.…”

New insight into the structure of dispersed titania by combining normal-mode analysis with experiment

“…In situ UV Raman experiments were performed on a multiwavelength Raman setup, consisting of a tunable Ti-sapphire laser (Indigo-S, Coherent), a triple Raman spectrometer (Princeton Instruments) and a confocal microscope (BX-51, Olympus) using 217.5 nm excitation [17]. The laser power was adjusted to 1 mW at the sample position.…”

“…For comparison with the calculations, UV Raman, UV-vis, and FT-IR spectroscopy have been used to characterize the structure of silica SBA-15-supported titania (Ti density: 0.7 Ti/nm 2 ). Raman experiments have been performed at an UV excitation wavelength to allow for selective resonance enhancement [9,17].…”

Recent advances in linear and nonlinear Raman spectroscopy. Part VIII

“…The potential of the setup is illustrated by new in situ Raman results on dispersed vanadium oxide catalysts obtained at 217.5 and 280 nm UV laser excitation. [246] Paz and Pablo described the determination of 1D spherically aberrated point spread function in depth profiling by confocal Raman microscopy. From the shape of point spread function, they obtained values of depth resolution within the film that confirm that axial discrimination is not drastically deteriorated, as suggested by previous works, and that confocal aperture effectively reduces the collection volume even under severe refraction interference.…”

“…described the technique of in situ diagnostics of catalytic materials using tunable confocal Raman spectroscopy. The potential of the setup is illustrated by new in situ Raman results on dispersed vanadium oxide catalysts obtained at 217.5 and 280 nm UV laser excitation . Paz and Pablo described the determination of 1D spherically aberrated point spread function in depth profiling by confocal Raman microscopy.…”