UV monochromator

Photoelectron spectroscopic studies were performed in an ultra-high-vacuum (UHV) photoelectron spectrometer, the details of which can be found elsewhere2 10. XPS was carried out using unfiltered Mg Ka radiation (125 3.6 eV photons), and with an electron energy analyser resolution such that the Au(4f7 2) line would have a FWHM of 0.9 eV. UPS was carried out with a He-resonance lamp, in connection with a 2 m grazing-incidence uv-monochromator, with the usual 21.2 eV and 40.8 eV photons. The electron energy analyser resolution was set to 0.2 eV in the XPS spectra and the Hell spectra, but to 0.1 eV in the Hel spectra. 

Figure 11.4 A double monochromator consisting of an air-path monochromator with a pre-monochromator for order sorting and stray light rejection to determine elements in the 190-900 nm range (b) the vacuum UV monochromator - an evacuated and argon-purged monochromator to routinely determine elements in the 160 to 500 pm range...

Capillary electrophoresis was carried out with a Capel 105 system (LUMEX, Russia) equipped with a UV monochromator (190-380 nm). A polyimide-coated fused silica capillary with an inner diameter of 75 jj.m, an outer diameter of 375 m and a total length of 61.5 cm (52 cm to the detector) was used. Data control was performed with personal computer software for Windows 95. The voltage used in all experiments was 20 kV (cathodic detection side). Between runs, the capillary was rinsed at high pressure for 3 min with 0.5 M NaOH and then with distilled water and flushed with the carrier buffer. 

Methods. Spectra were measured on low-temperature luminescence apparatus (excitation part 150W xenon arc lamp, H-20 UV monochromator... 

Infrared instruments using a monochromator for wavelength selection are constructed using double-beam optics similar to that shown in Figure 10.26. Doublebeam optics are preferred over single-beam optics because the sources and detectors for infrared radiation are less stable than that for UV/Vis radiation. In addition, it is easier to correct for the absorption of infrared radiation by atmospheric CO2 and 1420 vapor when using double-beam optics. Resolutions of 1-3 cm are typical for most instruments. 

Large high purity crystals ate cut into windows and refracting components for use in x-ray monochromators (14), and in the vacuum uv, uv, visible, and it ranges. 

Sohd-state multi-element detector arrays in the focal planes of simple grating monochromators can simultaneously monitor several absorption features. These devices were first used for uv—vis spectroscopy. Infrared coverage is limited (see Table 3), but research continues to extend the response to longer wavelengths. Less expensive nir array detectors have been appHed to on-line process instmmentation (125) (see Photodetectors). 

In situ quantitation Quantitative analysis (Figs. 2 and 3) could be performed both absorption-photometrically with long-wavelength UV light (2 = 365 nm) or fluorimetrically (2eic = 436 nm Afi = 546 nm [monochromation filter M 546] or 2fi > 560 nm). 

Fig.1 A modern analytical nltracentrifuge. a Beckman Optima XLA/I, with full on-line data captnre and analysis facility, b Its UV/visible monochromator and, for interference optics, the laser light sonrce are contained in the rotor chamber and have to be installed and removed at the start/end of each rnn...

In Raman measurements [57], the 514-nm line of an Ar+ laser, the 325-nm line of a He-Cd laser, and the 244-nm line of an intracavity frequency-doubled Ar+ laser were employed. The incident laser beam was directed onto the sample surface under the back-scattering geometry, and the samples were kept at room temperature. In the 514-nm excitation, the scattered light was collected and dispersed in a SPEX 1403 double monochromator and detected with a photomultiplier. The laser output power was 300 mW. In the 325- and 244-nm excitations, the scattered light was collected with fused silica optics and was analyzed with a UV-enhanced CCD camera, using a Renishaw micro-Raman system 1000 spectrometer modified for use at 325 and 244 nm, respectively. A laser output of 10 mW was used, which resulted in an incident power at the sample of approximately 1.5 mW. The spectral resolution was approximately 2 cm k That no photoalteration of the samples occurred during the UV laser irradiation was ensured by confirming that the visible Raman spectra were unaltered after the UV Raman measurements. 

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