Ultraviolet cells

Hunt DM, Wilkie SE, Bowmaker JK, Poopalasundaram S 2001 Vision in the ultraviolet. Cell Mol Life Sci 58 1583-1598... 

Table 9.1. References to infrared and Visible-Ultraviolet Cells for Air-sensitive Compounds... 

Low-temperature vacuum-tight visible-ultraviolet cell for solutions. 

Low- and htgh-icmpcraliirc gaslight visible-ultraviolet cell. 

The absorption spectra were obtained with a Hewlett-Packard 8451A diode array spectrophotometer and plotted as a wavelength verus transmittance from 220 nm to 340 nm. Sample solutions were prepared by dissolving an appropriate amount of chemical into the proper solvent. In the printed spectrum, the solvent solutions are represented by a solid line for the 0.2N H2SO4 solution and by a dashed line for strongly basic solution. A dotted line represents ethanolic solutions. Fisher-brand Suprasil ultraviolet cells were used for the sample solutions. The solutions were made basic by the addition of several drops of concentrated sodium hydroxide solution. 

Figure Bl.19.4. (a) Local conductance STS measurements at specific points within the Si(l 11)-(7 x 7) unit cell (symbols) and averaged over whole cell, (b) Equivalent data obtained by ultraviolet photoelectron spectroscopy (UPS) and inverse photoemission spectroscopy (IPS). (Taken from [19], figure 2.)...

TABLE 7.10 Ultraviolet Cutoffs of Spectrograde Solvents Absorbance of 1.00 in a 10.0 mm cell V5. distilled water. 

In LC, the most common means for monitoring the eluant is to pass it through a cell connected into an ultraviolet spectrometer. As substances elute from the column, their ultraviolet absorption is measured and recorded. Alternatively, the refractive index of the eluant is monitored since it varies from the value for a pure solvent when it contains organics from the column. 

Optical Applications. Vitreous siUca is ideal for many optical appHcations because of its excellent ultraviolet transmission, resistance to radiation darkening, optical polishing properties, and physical and chemical stabiUty. It is used for prisms, lenses, cells, wiadows, and other optical components where ultraviolet transmission is critical. Cuvettes used ia scatter and spectrophotometer cells are manufactured from fused siUca and fused quart2 because of the transmissive properties and high purity (222). 

Ultraviolet radiation around 254 mm renders bacteria incapable of reproduction by photochemically altering the DNA of the cells... 

These combined HDF and GPC separations require the use of detectors such as static light scattering or viscometers to help sort out the convoluted elution profiles seen in those type of experiments. It should also be remembered in these situations that the typical refractive index or ultraviolet detector responses may not be representative of the actual mass fraction of insolubles eluting from the column because of the significant light scattering that can occur with those large particles in the detector cell. 

Visual methods have been virtually displaced for most determinations by methods depending upon the use of photoelectric cells (filter photometers or absorptiometers, and spectrophotometers), thus leading to reduction of the experimental errors of colorimetric determinations. The so-called photoelectric colorimeter is a comparatively inexpensive instrument, and should be available in every laboratory. The use of spectrophotometers has enabled determinations to be extended into the ultraviolet region of the spectrum, whilst the use of chart recorders means that the analyst is not limited to working at a single fixed wavelength. 

A special titration cell is necessary which completely fills the cell compartment of the spectrophotometer. One shown in Fig. 17.24 can be made from 5 mm Perspex sheet, cemented together with special Perspex cement, and with dimensions suitable for the instrument to be used. Since Perspex is opaque to ultraviolet light, two openings are made in the cell to accommodate circular quartz windows 23 mm in diameter and 1.5 mm thick the windows are inserted in such a way that the beam of monochromatic light passes through their centres... 

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