Cylindrical cuvettes

Procedures. The light reflectance instrument was turned on 30 min prior to initiating reflectance observations. The sensitivity switch was set in the low position. The combination visible light emitter-reflectance detector was positioned vertically the active end of the detector faced upward. The sample cup was a glass cylindrical cuvette with optically flat bottom. A constant mass of 165 g (brass slug) was placed on top... 

By inserting either an interference filter or a colored filter, it is possible to select a more or less extended region of the spectrum likewise, by adding an optical fiber it is possible to direct the beam where desired. This set-up best exploits the characteristics of these powerful lamps, and offers an excellent choice for the irradiation of small surfaces. Consequently, spectrophotometric cuvettes or cylindrical cuvettes are used for the irradiation, which involves small volumes. Such restrictions, as well as the high price and short lifetime of the lamp and its accessories, favors the use of these arcs for kinetics studies and quantum yield measurements, rather than for preparative photochemistry. 

Conventional Raman spectroscopy utilizes rectangular or cylindrical cuvettes. A given spectrometer collects maximum intensity of Raman radiation of a sample, if the sample is placed in the focal region of a laser beam and if a maximum amount of the Raman radiation emerging from this sample is collected by a sample optics of the spectrometer within a maximum solid angle (Schrader, 1980). As mentioned in Sec. 3.1, the optical conductance of the entrance optics should have the same value as that of the interferometer or monochromator. Inspection of conventional sample arrangements shows that these conditions were often not fulfilled optimally ... 

CD Measurement. The CD spectra were obtained with a spectropolarimeter (JASCO 500) using a 0.2-mm path length cylindrical cuvette. At least 16 scans between 190 and 200 nm at a scan speed of 20 nm/mm were performed during each... 

Figure 5 shows the dependence of the total emission intensity on the excitation intensity and its spectral width obtained from DCM-encapsulated dendrimers. A nitrogen laser (wavelength of 337 run, pulse duration of 4 ns, and repetition rate of 10 Hz) was used as the excitation source. A cylindrical lens focused the excitation beam onto a stripe 200 pm wide on a quartz cuvette... 

Fig. 2.14 The scheme of the cylindrical lens method for diffusion coefficient measurement (1) the source with the horizontal slit (2) the condenser supplying a handle of parallel beams (3) the cuvette with a refraction index gradient where the beams are deflected (4) the objective lens focusing the parallel beams to a single point (5) the optical member with an oblique slit and a cylindrical lens (6) the photosensitive material...

Polymer films were made from solution (f)) and spread on quartz windows. To remove oxygen the films were kept for 2 hours at 10 5 Torr and then sealed off in cylindrical quartz cuvettes. 

Fig. 10. LS photometer60 for use at = 1086 nm A - laser, B - lens, C - shutter, D -rotating chopper, E - shutter, F - entrance window, G - thermostat vessel, H - metal shield, I - shutter, J - thermostat liquid, K - cylindrical LS cuvette, L - light trap, M - shutter,...

Isothermal DSC measurements were made with a Perkin Elmer DSC-2C apparatus, modified for UV irradiation (Figure 1). The aluminum sample holder enclosure cover contains two windows, one for the sample and one for the reference compartment. The windows consist of cylindrical quartz cuvettes which have been evacuated in order to prevent moisture condensation. The windows were mounted by using a thermally cured epoxy adhesive. 

Last but not least, the construction of the windows, which make measurements under the mentioned extreme conditions possible, should be discussed (209). Figs. 6.4a and 6.4b give schematic representation of the windows used in the described apparatus. Both windows are cuvettes, each made from one piece of glass (BK 7, Schott Gen.), with a flat bottom which is polished on both sides. With the window mounted in the bottom of the rotor unit (Fig. 6.4 a) the cuvette (1) is used in a position in which the bottom is on the upper side. With its outer cylindrical... 

As determined from HPLC, the purity of the peptide was greater than 90%. Steady-state fluorescence spectra of this peptide were collected from 310-480 nm with an excitation wavelength of 264 nm. A 1 cm pathlength cuvette was used with concentrations of 8.6 pM. The emission quantum yields were determined relative to N-acetyl-L-tryptophanamide at pH = 6.9 (f = 0.13) (17). Steady-state circular dichroism spectra were obtained using a 0.5 mm pathlength cylindrical cell and concentrations of 0.26 mM. The mean molar ellipticity [0] (deg cm dmol" ) was calibrated with (+)-10-camphorsulfonic acid. Concentrations of the solutions were determined by measuring the absorbance of 4-methylaminobenzoic acid. 

Detector flow cells are the link between the chromatographic system and the detector system. The cell cuvettes are made of quartz, with either cylindrical or square shapes and volumes between 5 and 20 /tL. The sensitivity is directly proportional to the volume. However, resolution decreases with increasing volume. Fluorescence is normally measured at an angle perpendicular to the incident light. An angle of 90° has the lowest scatter of incident light. However, fluorescence from the flow cell is isotropic and can be collected from the entire 360°. 

Photodegradation of six purified aromatic dyes All experiments were carried out in 10 mL cylindrical quartz cuvettes also placed in an RPR-200 Rayonet photochemical. Light sources were twelve 253.7 nm phosphor-coated low-pressure mercury lamps with a total power consumption of 400 watts. The light intensity at 1.5 inches from the lamps was about 21000 p watt/cm2 (Light intensity 2.4 x 10 5 Einstein L s 1) (Rabek J.K., 1982). The purified dyes were prepared at 50 mg/L, and were placed into the rotating merry-go-round photoreactor in which the cuvettes were exposed to same amount of UV light during the reaction. Samples were collected from each quartz cuvette at time 0, 15, 30, 60, 150, 240. 300 and 360 minutes, and then they were analysed by HPLC and/or UV-... 

The six selected Aromatic Dyes were irradiated in 10 mL cylindrical quartz cuvettes placed in a RPR-200 Rayonet photochemical reactor under different conditions ... 

The part of the leaf which was enclosed in the cuvette was excised, traced onto paper for evaluation of the surface area with an area meter LI-3000 (LI-COR Inc. Nebraska, USA). Tendrils area was corrected to take into account cylindrical surface. 

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