Paschen-Runge

Figure 2.6 Basic design of direct reading on a Paschen-Runge mount with fixed optics on a Rowland circle used in simultaneous ICP-AES. (Reproduced by kind permission copyright 1999-2008, all rights reserved, PerkinElmer, Inc.)...

Fig. 19. Important optical mountings for optical spectrometers with a plane (A Ebert, B Czerny-Turner) and a concave (C Seya-Namioka, D Paschen-Runge) grating, m Mirror, se entrance slit, sa exit slit, gp plane grating, gc concave grating.

Tab. 6. Analytical precision of spark ablation ICP-OES for a BAS 410/1 steel sample, ccu = 3.6 mg/g. Line pair leu 324.7 nm/lfe 238.2 nm- 400 Hz medium voltage spark, 1.5 kW argon ICP, transport gas flow 1.2 L/min, 0.5 m Paschen-Runge spectrometer, measurement time 10 s [213],...

Fig. 93. ICP-OES spectrometer CIROS-Paschen-Runge circle with detector alignement. (Courtesy of Spectro Analytical Instruments.)...

Figure 7.13 A Rowland circle polychromator. This configuration is called a Paschen-Runge mount. The source shown is an inductively coupled plasma, hut any of the electrical excitation sources can he substituted. Multiple photomultipler detectors are placed at the appropriate positions on the circumference of the circle to measure dispersed wavelengths. [From Boss and Fredeen, courtesy of PerkinElmer Inc. (www.perkinelmer.com).]...

The spectrometers used are adapted either for sequential or simultaneous multi-element measurements. Commonly used grating spectrometers in plasma AES include (i) spectrometers with the Paschen-Runge mount, (ii) echelle spectrometers, (iii) spectrometers with Ebert and Czerny-Turner mounts, (iv) spectrometers with Seya-Namioka mounts, and (v) double monochromators. Also Fourier transform spectrometers may be used in plasma AES. 

A Paschen-Runge mount is especially appropriate for multi-element... 

Another design of the Paschen-Runge mount for sequential measurements is shown in Figure 115. Here 255 fixed secondary slits with a regular spacing of 2 mm are mounted in the slit frame instead of the normal individual slits. Two movements are required to set the monochromator at a desired wavelength. First the carriage must be set to the specific exit slit, and then the entrance slit must be accurately moved to the desired spectral line. With... 

Fig. 12.28 Schematic diagram of a polychromator based on a Paschen—Runge mount and photomultiplier detection, (a) General optical set-up (b) side view and arrangement of the photomulitpliers.

The slit position and its relation to the angle of incidence should be chosen to take advantage of the highest reflectivity of the grating. The spectral order desired also must be considered. Some Paschen-Runge spectrometers have two fixed slits. By using angles of incidence of about 20° and 50°, both... 

FIGURE 4-12. Schematic diagram of the Paschen-Runge mounting for a concave grating. 

FIGURE 4-14. Optical diagram of a "folded" Paschen-Runge spectrometer. 

Spectrometer designs are similar to those already discussed, including broadband diode array, echelle, Czerny-Turner, and Paschen-Runge spectrometers, with miniature echelle and CCD array systems most suited to portable LIBS systems. The LIBSCAN 25+ (Applied Photonics Ltd.) uses up to 6 compact CCD array spectrometers covering the 185-900 nm range. Figure 7.53 shows the field-portable LIBSCAN 25-I-. 

---