Czerny-Turner

Figure 1 Drawing of single-channei Raman spectrometer showing Czerny-Turner type doubie monochromator. Coiiecting optica for scattered beam are not shown.

The potential of LA-based techniques for depth profiling of coated and multilayer samples have been exemplified in recent publications. The depth profiling of the zinc-coated steels by LIBS has been demonstrated [4.242]. An XeCl excimer laser with 28 ns pulse duration and variable pulse energy was used for ablation. The emission of the laser plume was monitored by use of a Czerny-Turner grating spectrometer with a CCD two-dimensional detector. The dependence of the intensities of the Zn and Fe lines on the number of laser shots applied to the same spot was measured and the depth profile of Zn coating was constructed by using the estimated ablation rate per laser shot. To obtain the true Zn-Fe profile the measured intensities of both analytes were normalized to the sum of the line intensities. The LIBS profile thus obtained correlated very well with the GD-OES profile of the same sample. Both profiles are shown in Fig. 4.40. The ablation rate of approximately 8 nm shot ... 

A detachable monochromator (19) developed by Spex Industries, was another approach in minimizing stray light. It is a modified Czerny-Turner spectrograph which can be coupled to the exit slit of a double monochromator and function as a variable bandpass, variable frequency filter. This accessory, while providing the versatility of a triple monochromator, does not add much mechanical and optical complexity and can be removed when not wanted. 

Spex Ramalog 4 0.18 at 17628 cm-1 10-10 (20A cm-1 from Czerny-Turner double grat- 0.85 1200 lines/mm, blazed at... 

Jasco R300 2 10 Czerny-Turner double grat- 0.4 — ... 

Czerny-Turner spectrograph spect A spectrograph used chiefly in laboratory work, which has a plane reflection grating and spherical reflectors for the collimator and camera. cher-ne t3rn 3r spek-tra.graf)... 

KW, 27.12MHz automatic Im Czerny-Turner monochromator impedance matching... 

Common grating mountings used in ICP-AES (a) Ebert (b) Czerny-Turner. 

Q. Name two ways of increasing the resolution of a Czerny-Turner monochromator. 

M3, which compensates for aberrations and yields an excellent quality of image b) Czerny-Turner design, similar in conception, incorporating two spherical mirrors. M and jf/4 c) design with a concave grating (7( allowing simultaneous dispersion and focusing of the radiation. The spectral bandwidth of these monochromators depends on the width of the entrance and exit slits, F, and F2-... 

Figure 21 -25 A Cd line at 228.802 nm causes spectral interference with the As line at 228.812 nm in most spectrometers. With sufficiently high resolution, the two peaks are separated and there is no interference. The instrument used for this spectrum has a 1-m Czerny-Turner monochromator (Figure 20-5) with a resolution of 0.005 nm from 160 to 320 nm and 0.010 nm from 320 to 800 nm. [Courtesy Jobin Yvon Horiba Group. Longjumeau Cedex. France.]...

Fig. 1.6. Comparison of dispersive (Czerny-Turner) and FT (Micheison interferometer) spectrometers...

These tubes have been employed with both one- and two-dimensional dispersive systems. For example, Harber and Sonnek (43) described an electronic scanning spectrometer based on an image-dissector photomultiplier in conjunction with a onedimensional dispersive system. Their system used a 12.7 cm Czerny-Turner mount with a reciprocal linear dispersion of... 

Dispersing elements may be either prisms (glass for the visible, quartz for the nearultraviolet) or, more often, diffraction gratings for which a Czerny Turner mounting, shown in Figure 3.17, may be used. 

Monochromators (a) Czerny-Turner grating monochromator, (b) Bunsen prism monochromator. 

Luminescence spectra were recorded on a double Czerny-Turner scanning monochromator Model 1902 Fluorolog Spex spectrof1uoro-meter. Variations in the excitation radiation are automatically corrected by a reference detector equipped with a Rhodamine B quantum counter. Emission spectra were recorded with the right angle mode. Further details are available elsewhere (31). 

An imaging spectrograph differs from a conventional (e.g., Czerny-Turner) design in that it maintains the one-to-one correspondence of the entrance slit and its image at the detector. So a circular fiber positioned at the entrance... 

Figure 8.3. Schematic of a single grating Czerny-Turner spectrograph. Shading indicates envelope of light passing through the instrument, which disperses and focuses wavelengths at the focal plane.

The single grating instrument depicted in Figure 8.3 is very common in optical spectroscopy (1), but its application to Raman is relatively recent because of inadequate stray light rejection. The introduction of effective laser rejection filters (Section 8.2.5) removed this limitation and single spectrographs became attractive. They are simpler and more efficient than double or triple systems and usually much more compact. Variations of the classical Czerny-Turner... 

Use your favorite search engine to find companies that manufacture monochromators. Navigate to several Web sites of these companies and find a UV/visible monochromator of the Czerny-Turner design that has better than 0.1-nm resolution. List several other important specifications of monochromators, and describe what they mean and how they affect the quality of analytical spectroscopic measurements. From the specifications and, if available, the prices, determine the factors that have the most sianificant effect on the cost of the monochromators. 

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.

With a plane grating several mountings (Fig. 19) can be used. In the Czerny-Turner mounting, two spherical mirrors with slightly different focal lengths are... 

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