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A novel cavity-enhanced laser diagnostic has been developed to perform point measurements of spontaneous rotational Raman scattering. A narrow linewidth fiber laser source (1064 nm) is frequency locked to a high-finesse cavity containing the sample gas. Intracavity powers of 22 W are generated from 3.7 mW of incident laser power, corresponding to a buildup factor of 5900. A triple monochromator and a photomultiplier tube in counting mode are used to disperse and measure the scattering spectra. The system is demonstrated with rotational Raman spectra of nitrogen, oxygen, and carbon dioxide at atmospheric pressure. The approach will allow temporally and spatially resolved Raman measurements for combustion diagnostics and, by extending to higher power, Thomson scattering for diagnostics of low-density plasmas.
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http://dx.doi.org/10.1364/OL.41.003193 | DOI Listing |
J Am Chem Soc
September 2025
Soochow Institute for Energy and Materials Innovations, College of Energy, Soochow University, Suzhou 215006, P. R. China.
Electrocatalytic CO reduction (eCOR) under acidic conditions is the game changer of resourceful CO utilization owing to the alleviated carbon loss but faces severe competition from the hydrogen evolution reaction (HER) that greatly curtails the electric current efficiency. Leveraging the eCOR side of the teeterboard calls for a fundamental understanding of the triphasic electrode process involving a complex arrangement of electric double layers (EDLs). Herein, a series of model catalysts with tailored cavernous parameters are fabricated to geometrically and spectroscopically decipher the competing HER and eCOR processes that engage different proton sources.
View Article and Find Full Text PDFDalton Trans
September 2025
School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK.
Distortions in the local symmetry around Ln(III) ions in SMMs significantly impacts slow magnetic relaxation by introducing transverse crystal field parameters that enhance quantum tunnelling of the magnetisation (QTM). Minimising these distortions, often using macrocyclic or sterically hindered ligands, or by tuning intermolecular interactions, is essential for suppressing QTM. A less-explored strategy involves aligning the molecular symmetry elements within the crystal lattice to generate a high-symmetry crystal lattice with symmetry enforced bond angles and lengths.
View Article and Find Full Text PDFLiquid-core fibers, which are hollow core fibers or capillaries filled with liquids as core materials, have been attractively explored for various applications, especially in nonlinear optofluidics. High nonlinear refractive indices of selected liquids enable broadband supercontinuum generation. Unlike solid glasses, the nonlinear properties of liquids are more complex, including a contribution of electro-bound (instantaneous) nonlinearity and molecular rotation and vibration under external laser pulses (i.
View Article and Find Full Text PDFPhys Rev Lett
July 2025
Eötvös Loránd University, ELTE, Institute of Chemistry, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary.
Rovibrational energies, wave functions, and Raman transition moments are reported for the lowest-energy states of the H_{3}^{+} molecular ion including the magnetic couplings of the proton spins and molecular rotation in the presence of a weak external magnetic field. The rovibrational-hyperfine-Zeeman Hamiltonian matrix is constructed and diagonalized using the rovibrational eigenstates and the proton spin functions. The developed methodology can be used to compute hyperfine-Zeeman effects also for higher-energy rovibrational excitations of H_{3}^{+} and other closed-shell polyatomic molecules.
View Article and Find Full Text PDFA technique for quantitative two-photon laser-induced fluorescence measurements of the ←(=0) Hopfield-Birge system in high-enthalpy environments is shown. The two-photon transition is pumped by high-intensity, nanosecond laser excitation to produce photoionization rates much greater than the quenching rates at the probe volume, which simplifies the quantification of the signal. We demonstrate this technique along the stagnation streamlines of a graphite ablator exposed to the 6000 K plume of an atmospheric-pressure inductively coupled air plasma torch.
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