The Model 303 is a 250mm focal length f/4 prism monochromator with good throughput. It is built like a Czerny-Turner and uses a prism in Littrow configuration for refraction. Prisms do not have multiple orders like diffraction gratings and are capable of very low dispersion. The 303 monochromator used with slits works as a tunable filter, or cut filter for UV-Raman applications. Used with a wide exit slit (or by removing the exit slit) the focal plane accepts an imaging CCD or infra-red bolometer array (for example).
Abstract: A filtered Thomson scattering technique has been developed to measure electron temperature Te, and electron number density ne in an atmospheric pressure argon plasma. The problems of the strong background scattered light and the high plasma luminosity were resolved by employing an atomic vapor filter that provided strong attenuation of stray scattered light at the laser wavelength while simultaneously allowing the passage of spectrally broad Thomson scattered light. A relatively low power Ti:sapphire laser (about 50mJ/pulse) was used in conjunction with an optically thick rubidium notch filter. High spectral purity of the laser was achieved by developing an amplified simulated emission filter. Because of the geometrical constraints of the plasma arc source, experiments were performed in the backscatter geometry. Information on the electron number density and electron temperature was derived from the Thomson signal by fitting a model curve to the data. The measurements results gave an electron temperature of 0.82 ± 0.05 eV and electron number density of 1.61 x 10E16 ± 0.05 x 10E16 electrons/cm3
Sohail H. Zaidi; Z. Tang; A. P. Yalin; P. Barker; R. B. Miles
Abstract: We describe an ultraviolet resonance Raman (UVRR) spectrometer appropriate for structural studies of biological macromolecules and their assemblies. Instrument design includes the following features: a continuous wave, intracavity doubled, ultraviolet laser source for excitation of the Raman spectrum; a rotating cell (or jet source) for presentation of the sample to the laser beam; a Cassegrain optic with f/1.0 aperture for collection of the Raman scattering; a quartz prism dispersing element for rejection of stray light and Rayleigh scattering; a 0.75-m single grating monochromator for dispersion of the Raman scattering; and a liquid-nitrogen-cooled, charge-coupled device for detection of the Raman photons. The performance of this instrument, assessed on the basis of the observed signal-to-noise ratios, the apparent resolution of closely spaced spectral bands, and the wide spectrometer bandpass of 2200 cm-1, is believed superior to previously described UVRR spectrometers of similar design. Performance characteristics of the instrument are demonstrated in UVRR spectra obtained from standard solvents, p-ethylphenol, which serves as a model for the tyrosine side chain, the DNA nucleotide deoxyguanosine-5'-monophosphate, and the human tumor necrosis factor binding protein, which is considered representative of soluble globular proteins.
M.P. Russell, S. Vohník, G.J. Thomas Jr
Abstract: New EuIII Schiff base compounds and polyelectrolytes luminesce with quantum yields consistent with the intramolecular energy transfer mechanism established for EuIII β-diketone complexes. The emission spectra clearly show that the two EuIII ions in Eu2L3 complexes, where L is a tetradentate Schiff base ligand, are in different environments, that the Na[Eu(L)2] complexes exhibit higher quantum yields than the corresponding Eu2L3 species, and that luminescence is negligible when the ligand triplet-state lies below the 5Do state of EuIII.
Ronald D. Archer, Huiyong Chen, Larry C. Thompson
Abstract: We report the syntheses and a spectroscopic characterization, including X-ray diffraction, of the 2,2‘-dipyridyl adducts of two europium β-diketonate complexes, EuL3·bipy (L = 4,4,4-trifluoro-1-phenyl-2,4-butanedione or L = 1-phenyl-2,4-butanedione). Theoretical calculations of excited electronic states of both compounds have shown that the increase of the quantum yield in the fluorinated complex is related to a decrease in the bipy−Eu distance, to a closer match of the lowest ligand-centered triplet state, and to the lower vibrational frequency associated with CF3 relative to the CH3 groups.
Hélcio J. Batista, Antônio V. M. de Andrade, Ricardo L. Longo, Alfredo M. Simas, Gilberto F. de Sá, Nao K. Ito, and Larry C. Thompson