Quartz crystal monochromatization

In 1892, Biot confirmed that the colors on propagating white light parallel to the optical axis of a quartz crystal placed between crossed polarizers arise from two distinct effects, the rotation of the plane of polarization of monochromatic light and dispersion of the rotation with respect to wavelength. Biot s discovery was extended to the optical rotation of natural products in solution or in the liquid phase, and this is of chemical significance, as it indicates that rotation is a molecular effect. 

On the other hand, the monochromator has the great advantage that it automatically eliminates the Ka3i4-satellites. Fig. 6 demonstrates that this can be achieved as well with the help of a Fourier transform filtering program, allowing a satellite free spectrum also for Magnesium irradiation where monochromatization with the help of a spherically bent quartz crystal so far has not been shown. 

Probe-beam deflection is a technique in which a monochromatic source, typically a He-Ne laser beam, passing parallel to the electrode surface, is used to monitor refractive index changes in the diffusion layer. It is a simple and cost-effective way of profiling the diffusion layer, and is used to monitor the diffusion layer ingress and egress of ions, particularly protons. It is often used in conjunction with electrochemical quartz crystal microbalance (EQCM) measurements that monitor mass changes within or on the electrode layer itself. 

We have at present a maximum of 25 spherically bent quartz crystals (c )=30 mm) mounted for simultaneous focusing of the AlKa radiation onto the sample in front of the spectrometer slit. The result of the monochromatization is shown in Fig.40. It is fortuitous that at an almost identical Bragg angle ( > 78 ) as first order focusing of AlKa 2 occurs, second order focusing of AgLa, third order ScKg ... 

Fig. 40. Monochromatization of AlKa from spherically bent quartz crystal (010).

We determined the absorption of the laser pulse by recording the scattered and specularly rehected laser light with 47r-arranged calorimeters. In front of the calorimeters, a 2-mm thick quartz plate was installed to block charged particles and X-rays. In some experiments, low-order harmonics of the laser beam were analyzed using a monochromatic meter. Crystal spectrometers were used to record the plasma self-emission of X-rays, from which the ionization states of the target materials were obtained. 

The catalysts were prepared by impregnating Ca(OH)2 with aqueous solution of NaOH applying the incipient wetness method. After impregnation the samples were dried and calcined in CO2 free air at 973 K. Other alkaline earth oxides (Analar) were also used for activity measurements. X-ray diffraction studies were carried out in a Phillips instrument using a Guinier camera applying crystal reflected monochromatic CuK a radiation. IR spectra were recorded by a Perkin-Elmer FTIR 1710 spectrometer. The samples were dried for 1 Oh at 383 K prior to preparing the pellets. The catalytic experiments were carried out in a quartz made reactor, details of the reactor operation and product analysis have been described elswhere [8]. 

The effect of the degree of perfection of monochromator crystals on the basic characteristics of focusing monochromators, and particularly on the intensity of the reflected beam, has not received its due attention in the literature. For example, it has been considered [5] that tubes with small focus dimensions and the most perfect crystals must be used to obtain a narrow intense beam of monochromatic radiation. However, measurements made on quartz of different degrees of perfection [6] showed that the maximum intensity of a monochromatic beam is observed for "average" degrees of perfection of the monochromator crystal. 

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