We report the first known demonstration of frequency-modulation spectroscopy outside the visible spectral region. Specifically, we report the use of second-harmonic generation on a frequency-modulated visible dye-laser beam to produce a frequency-modulated ultraviolet beam that is used to observe the Na 3S ? 4P absorption at 3302 A.
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http://dx.doi.org/10.1364/ol.8.000157 | DOI Listing |
Anal Chem
January 2025
Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States.
Charge detection mass spectrometry (CDMS) allows direct mass measurement of heterogeneous samples by simultaneously determining the charge state and the mass-to-charge ratio (/) of individual ions, unlike conventional MS methods that use large ensembles of ions. CDMS typically requires long acquisition times and the collection of thousands of spectra, each containing tens to hundreds of ions, to generate sufficient ion statistics, making it difficult to interface with the time scales of online separation techniques such as ion mobility. Here, we demonstrate the application of Fourier transform multiplexing and drift tube ion mobility joined with Orbitrap-based CDMS for the analysis of multimeric protein complexes.
View Article and Find Full Text PDFSensors (Basel)
January 2025
Department of Electronics Engineering, Kaunas University of Technology, 51368 Kaunas, Lithuania.
The application of spread-spectrum signals (arbitrary pulse width and position (APWP) sequences) in air-coupled resonant ultrasound spectroscopy is studied. It was hypothesized that spread-spectrum signal optimization should be based on te signal to noise ratio (SNR). Six APWP signal optimization criteria were proposed for this purpose.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
Astrophysik/I. Physikalisches Institut, Universität zu Köln, Köln 50937, Germany.
The methoxy radical, CHO, has long been studied experimentally and theoretically by spectroscopists because it displays a weak Jahn-Teller effect in its electronic ground state, combined with a strong spin-orbit interaction. In this work, we report an extension of the measurement of the pure rotational spectrum of the radical in its vibrational ground state in the submillimeter-wave region (350-860 GHz). CHO was produced by H-abstraction from methanol using F atoms, and its spectrum was probed in absorption using an association of source-frequency modulation and Zeeman modulation spectroscopy.
View Article and Find Full Text PDFPolymers (Basel)
November 2024
Chemistry Department, Science College, King Saud University, Riyadh 145111, Saudi Arabia.
Local Khulays clay was modified to prepare polystyrene clay nanocomposite (PCN) coatings on carbon steel. The PCN coatings were added to microcapsules (MCs) loaded with the corrosion inhibitor PCN(MC). The microcapsules were prepared by the encapsulation of rare-earth metal Ce ions and isobutyl silanol into polystyrene via the double emulsion solvent evaporation (DESE) technique.
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November 2024
Laboratory of the Molecular Imaging and Machine Learning, Tomsk State University, 634050 Tomsk, Russia.
A standard measuring gas cell used in absorption spectrometers is a cylinder enclosed by two transparent windows. The Fabry-Perot effects caused by multiple reflections of terahertz waves between these windows produce significant variations in the transmitted radiation intensity. Therefore, the Fabry-Perot effects should be taken into account to correctly measure absorption spectra in Bouguer law-based absorption spectroscopy.
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