Mercury emission spectrum

A Beckman DU spectrophotometer was used for all measurements. The slit width was chosen so that a half-intensity band width of 1.6 nm was obtained in the region X = 650-590 nm, 0.6 nm in the region X = 590-A60 nm, and 0.15 nm in the region of the Soret bands. The wavelength of the instrument had been checked with the aid of the mercury emission spectrum. Measurements at X > 590 nm were made in a layer thickness of 0.0993 cm, at X < 590 nm in a layer thickness of 0.0128 cm. The latter was obtained by inserting a plane parallel glass plate into the 0.0993-cm cuvette (Fig. 13). The layer thickness of the cuvette had been determined spectrophotometrically using HiCN solutions and a 1.000-cm cuvette as a reference. 

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 emission spectrum for mercury shows that it has more spectral lines than the emission spectrum for hydrogen. 

Figure 19 shows the ultraviolet absorption spectrum of a typical diazonaphthoquinone and a common novolac resin. The naphthoquinone sensitizer has a strong absorbance at the 365 nm., 405 nm., and to a lesser extent the 436 nm. mercury emission lines. There are two diazonaphthoquinone isomers that are used in commercial photoresist formulations that are available at this time. The 5-arylsulfonates are by far the most commonly used. A spectrum of a representative of this class of materials is depicted in Figure 20. The 5-arylsulfonate materials are characterized by an absorbance maximum at approximately 400 nm. and a second, slightly stronger maximum at approximately 340 nm.

Figure 19. Absorbance spectrum of a typical diazonaphthoquinone sensitizer (in solution) and a cresylic acid novolac (film). The wavelengths of principle mercury emission lines are labeled.

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). 

Emission spectrum Radiation from an atom in an excited state, usually displayed as radiant power vs. wavelength. Each atom or molecule has a unique spectrum. The spectra can be observed as narrow line emission (atomic emission spectra) or as quasi-continuous emissions (molecular emission spectra). A mercury plasma emits both line spectra and continuous spectra simultaneously. 

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... 

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. 

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... 

Fig. 16. The appearance of rotatory artifacts both at the minimum in the emission spectrum of the mercury arc and as increasing polypeptide absorption is encountered below 250 m/i. The rotations are those actually observed, a, in degrees, for a 0.6% poly-L-glutamic acid solution at pH 7 in a 10-cm cell. The absorption spectrum of poly-L-glutamic acid and the emission spectrum of the arc, uncorrected for detector response, are in arbitrary units. (Urnes et al., 1961b.)...

Mercury s atomic emission spectrum is shown below. Estimate the wavelength of the orange line. What is its frequency What is the energy of an orange photon emitted by the mercury atom ... 

The PM and TPS photoinitiators generally gave shorter tack-free times than DPI and at the lower concentration level, PM was somewhat more effective than TPS. This can be attributed to the more efficient use of the mercury arc radiation by the PM photoinitiator, which has an absorption peak at 313 nanometers (Figure 4), corresponding to a peak in the emission spectrum of the mercury arc. Absorption maxima for DPI and TPS are at the lower end of the spectrum, far removed from the peak output of the high pressure mercury arc. 

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. 

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