Mercury lamp, emission spectra

An explanation of the differences in cure rate between DPI and TPS is less obvious, as the absorption spectra of these two compounds are -similar. Depending on the method of preparation, however, the TPS photoinitiator frequently shows some absorbance in the spectral region between 290 and 340 nm, overlapping the band at 310 in the mercury lamp emission spectrum. This may be the result of a fortuitous contaminant not completely removed in synthesis and purification of the TPS photoinitiator. 

In contrast to the low-pressure lamps (1—130 Pa) which primarily emit at the resonance line at A = 254nm, high-pressure lamps (lO —10 Pa) also produce numerous bands in the UV and VIS regions (Fig. 16). Table 3 lists the emission lines and the relative spectral energies of the most important mercury lamps (see also [44]). The addition of cadmium to a mercury vapor lamp increases the numbei of emission lines particularly in the visible region of the spectrum [45] so that it i. also possible to work at A = 326, 468, 480, 509 and 644 nm [46]. 

Fluorescent lamps generate light through a low-pressure mercury vapor discharge that has strong emission tines in the UV, namely at A = 254 nm and around 366 nm. The fluorescent layer is excited by the UV radiation and emits in the visible part of the spectrum. While remains of the 254 nm tine are efficiently rejected by the glass tube, some fraction of the 366 nm radiation can be measured in the emission spectrum of the lamp. 

An emission spectrum for pure mercury obtained from a mercury lamp. It is easy to see that mixed sources, and higher energy excitation will produce very complex patterns of lines, demanding high quality optical... 

The most frequently used lamp for UV curing processes is medium-pressure mercury lamp. Its emission spectrum can be used to excite the commonly used photoinitiators. Moreover, this type of lamp has a relatively simple design, is inexpensive, can be easily retrofitted to a production line, and is available in lengths up to 8 ft (2.5 m). Power levels in common use are in the range 40 to 240 W/cm, and even higher levels are available for special applications. ... 

Doped lamp Term applied to a UV mercury lamp containing metal halide added to the mercury to alter the emission spectrum of the lamp (preferred term is additive lamp). 

Figure 10.3. (b) Emission spectrum of mercury vapor lamp. 

Figure 6 shows the absorption curve for acetone superimposed upon the emission spectrum of a medium pressure mercury vapor lamp of the type commonly used in photochemical investigations. If the possibility of mercury photosensitization is neglected, it can be seen that the emission line in the mercury spectrum which will be most effective in photolysis is that at 3130 A., and, in fact, this line is frequently isolated by the... 

The solution of C60H18 has been irradiated inside a quartz reactor with a low pressure mercury lamp having a monochromatic emission at 245 nm. The solution was kept under continuous He blanket to avoid any interference from air. Periodically samples from the irradiated solution were taken to measure the electronic absorption spectrum. 

Wavelength accuracy. In order to evaluate the ability of each system to locate spectral lines, a preliminary wavelength calibration was carred out with the emission spectrum of a mercury pen lamp and then the peak maxima of several atomic lines from an iron hollow cathode lamp were located. The root mean square (RMS) prediction error, which is the difference between the predicted and the observed location of a line, for the vidicon detector system was 1.4 DAC steps. Because it is known from system calibration data that one DAC increment corresponds to 0.0125 mm, the absolute error in position prediction is 0.018 mm. For the image dissector, the RMS prediction error was 7.6 DAC steps, and because one DAC step for this system corresponds to 0.0055 mm, the absolute error in the predicted coordinate is 0.042 mm. The data in Table II represent a comparison of the wavelength position prediction errors for the two detectors. 

On the other hand, medium-pressure (MP) Hg lamps can be operated with much higher electrical input power up to 30 kW, but with a reduced UV radiant power efficiency of 30 to 40%. Their dimensions are more compact than the dimensions of the LP Hg lamps, but their polychromatic emission ranges from the UV (UV-C - 15-23%, UV-B - 6-7 %, UV-A - 8%) over the VIS (-15%) to the IR (-47-55%) region of the electromagnetic spectrum (e.g. McClean, 2001). Lam-brecht (1999) reported the power balance of electromagnetic radiation of an industrially used high-pressure mercury lamp with a power density of 200 W cm as follows 13.2% UV-C, 7.15% UV-B, 7.15% UV-A, 21% VIS, and 14% IR... 

Fig. 4.6 Typical emission spectrum of a 1 kW medium-pressure mercury lamp (E values were made available by Heraeus Noble-light, Kleinostheim, Germany).

Emission Spectrum. Several sources are suitable for exciting the emission spectrum of I2. In previous editions of this text, the use of a low-pressure mercury discharge lamp was described, in which the green Hg line at 546.074 nm causes a transition from... 

In emission spectroscopy the molecule or atom itself serves as the somce of light with discrete frequencies to be analyzed. In some cases, such as Exp. 39, which deals with the emission spectrum of molecular iodine vapor, excitation by a monochromatic or nearly monochromatic laser or mercury lamp is utilized. For other cases, such as the emission from N2 molecules, electron excitation of nitrogen in a discharge tube provides an intense somce whose spectrum is analyzed to extract information about the electronic and vibrational levels. Such low-pressure (p < 10 Torr) line somces are available with many elements, and lamps containing Hg, Ne, Ar, Kr, and Xe are often used for calibration purposes. The Pen-Ray pencil-type lamp is especially convenient for the visible and... 

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