Oscillation camera

The Pyrex tube was suspended, with capillary down, in a small-holed rubber stopper which, in turn, was fastened to a goniometer head by a length of stout copper wire. The solid material within the capillary was photographed in a cold room (4°C.) using copper x-radiation, a camera with radius 5 cm., and oscillation range 30°. The effective camera radius was established by superimposing a powder spectrum of NaCl during an exposure of the sample the lattice constant for NaCl at 4°C. was taken to be 5.634 A. 

Only from 1985 onwards could we seriously consider crystallographic data collection. In fact, several full sets of oscillation films have since been exposed on the rotation camera however, they have tended to become outdated in view of new developments in the crystallization techniques or by other experimental improvements. 

Fig. 15. A Weissenberg photograph of (o-amino acid pyruvate aminotransferase (mercury derivative). A single bent triangular Si(lll) monochromator and a Weissenberg camera for macromolecular crystallography were used. The oscillation angle 30° the radius of the camera 287 mm, exposure time 4.7 min...

Of the many types of X-ray cameras, only two are still in even occasional use in protein crystallography — the Buerger or precession camera and the rotation/oscillation camera. The precession camera is used primarily in... 

Precession cameras are complex but give the diffraction pattern in its simplest, most understandable form. Rotation/oscillation cameras are far simpler, merely providing means to rotate the crystal about an axis perpendicular to... 

IRS and OHD-RIKES are less effected by the background interference, but the signal levels tend to be low, and they are subject to noise in the broad-band dye laser probe. Attempts to eliminate the remaining noise by time dispersal of the Raman signal and local oscillator by means of a streak camera (9) or a smoothing of the dye probe mode structure by intracavity phase shifting of the dye radiation are under consideration. 

In collaboration with Alexander Gorbach, NIH, we have initiated a study of the spatial patterns in the nephron synchronization. This study involves the use of infrared cameras or other types of equipment that can measure variations in the blood supply by small (0.01°C) fluctuations in the temperature at the surface of the kidney. It is also of interest to study how the large amplitude oscillations in pressure, fluid flow, and salt concentration at the entrance of the distal tubule influence the delicate hormonal processes in that part of the kidney, to establish a more quantitative description of some of the mechanisms involved in the development of hypertension, and to examine the effects of various drugs. 

Figure 1. Diagram of apparatus for picosecond fluorescence studies using streak camera detection. A laser oscillator B dye cell C output reflector D polarizer E spark gap F KDP pockels cell G polarizer (crossed with D) H clear glass beamsplitter J laser amplifier K pin photodiode L transient digitizer M,N 1054 nm reflectors P 2nd harmonic generator Q 3rd or 4th harmonic generator R spectrograph S streak camera T biplanar photodiode U image...

To synchronize the fluorescence to the continuous sinusoidal deflection voltage of the streak camera, 10% of the visible output from the dye laser was directed onto a pin photodiode which was used to trigger a tunnel diode oscillator. The output of this oscillator was then frequency... 

Finally, the advent of planar charge-coupled devices replaced films and photomultipliers, and it enabled Arndt148 oscillation cameras (logically... 

The Peierls169 metal-to-semiconductor phase transition in TTFP TCNQ p was detected in an oscillation camera these streaks became bona fide X-ray spots only below the phase transition temperature of 55 K this transition is incommensurate with the room-temperature crystal structure, due to its partial ionicity p 0.59, and the "freezing" of the concomitant itinerant charge density waves (this effect was missed by four-circle diffractometer experiments, which had been set to interrogate only the intense Bragg peaks of either the commensurate room-temperature metallic structure, or the commensurate low-temperature semiconducting structure). 

FIGURE 7.11. An X-ray diffraction photograph obtained by oscillating a crystal about a vertical axis, (a) Arrangement of camera and crystal, and (b) the resulting diffraction pattern. Note that the a axis is perpendicular to the 6 and c axes. With one crystal lattice aocis vertical, layer lines (each with a constant value of / in a given layer) are produced. 

In the Weissenberg method the crystal is also oscillated about an a.xis. The camera has, in addition, a metal screen with a slit in it that selects out a single layer line and excludes all other layer lines. In order... 

The Laue method involves a stationary crystal and polychromatic ( white ) X rays. In the other camera methods, monochromatic radiation is used. In these cases the crystal may be oscillated over a small angular range (oscillation method) or rotated 360° about an axis (rotation method). The layer lines so formed may be selected individually. In the Weissenberg method, the oscillation of the crystal is coupled with a movement of the photographic film. The Buerger precession method, by a more complex motion of the instrument, produces an undistorted and magnified picture of the reciprocal lattice. 

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