The invention relates to the field of x-ray diffraction and rentgenotopograficheskaya non-destructive methods of investigating the structure and quality control of materials and is intended for shaping the x-ray beam, in particular beam of synchrotron radiation (SR), using crystal monochromators and focusing system consisting of two mirrors.
As a prototype x-ray system selected device for forming x-ray beam, as described in Wei, Euerek, Sigalagala, Weavologist, Unilin, Vasilkov // Surface. X-ray, synchrotron and neutron studies. 2004. No. 7. Pp.5-14. The SR beam after successive reflections from the two crystal monochromators, located in the dispersionless scheme diffraction, is sent to the control module spatial position of the beam consisting of two flat mirrors of total external reflection (AA). The first mirror is set at a fixed angle to the beam; its task is to bring the beam from the horizontal plane. Rotation and linear movement in the scattering plane of the second mirror is the angle of incidence of the beam on the organic nanoplasma on the surface of the liquid subphase (hereinafter "liquid sample"). In the course of the experiment remains the same, the position of the area of ASDs is etki beam on the sample without moving Langmuir baths. When used as the first mirror focusing mirror with a cylindrical surface area exposure may be reduced. This fact provides a basis for the optimal use of energy dispersive detector fluorescent radiation, since the latter has a limited bodily receiving angle. However, when the fixed focusing mirror in the course of the experiment, the size of the area of illumination is not constant, which may affect the accuracy of the experiment.
The objective of the invention is to provide a method of controlling a spatial position of the x-ray beam using a serial reflect pre monochromatizing beam of synchrotron radiation from the two mirrors, with a cylindrical and flat surfaces, moving along the beam and rotation of the second mirror about an axis normal to the plane of the scattering of x-rays to ensure the constancy of the size of the area illuminated horizontal surface of the investigated liquid sample at different values of the angle between the x-ray beam and sample surface.
The problem is solved in that produce rotation of the first mirror about an axis normal to the plane of the scattering of x-rays, and the angle θ1between the beam and the first mirror is ω and the angle θ 2between the beam and the second mirror connected by the relation:
θ2=[θ1(1-2kθ1)-A]/2kθ1,
where k and a are parameters that depend on the beam energy, the radius of curvature of the cylindrical surface of the first crystal and the linear parameters of the station.
The invention explains the x-ray diagram of the device shown in the drawing. Slightly divergent beam of SI generated by the source 1, sent for double-crystal monochromator. Its crystals 2 and 3 are in parallel position (n, -n), providing, thus, dispersionless x-ray diffraction (RL). Generated by the monochromator the beam extends in a direction parallel to the primary beam C, and its spatial position is not changed when changing the angular position of the crystals. Monochromatizing x-ray beam output from the horizontal plane of the focusing by total external reflection mirror 4. The mirror has a surface of a circular cylinder of constant radius. The second mirror 5 with a flat working surface directs the beam onto a liquid sample 6. Angle α formed between the optical beam and the sample surface during the experiment varies from αminto αmaxand
| 1 max=2(θ2c-θ1c), | (1) |
where θ1 cand θ2 crespectively the values of the critical angles defense for the first (focusing) and second (flat) mirrors. Focal length q is related to the magnitude of the radius R of the focusing mirror and the distance p from the x-ray source to mirror the expression:
| 2/Rθ1=1/p+1/q. | (2) |
Such a mirror may be used to control the angular divergence Δα formed beam (see drawing):
| Δα/Δθ=p/q. | (3) |
Here Δθ - the divergence of the primary beam C.
Using formulas (2), (3) and drawing it is easy to obtain an expression for the size of the light D the surface of the liquid sample beam:
| D=L(1+l/R 2l/Rθ1)(pΔθ/Lα), | (4) |
where l is the distance between the mirror 4 and the center of the field of illumination. From (4) it follows that in the case of a flat 4 (R=∞) the size of the area of illumination is inversely proportional to the corner α. However, when R≠∞ it is possible to achieve invariance of the size of exposure (D=const) throughout the exposure is of riment (i.e. when the variation of the angle α). To do this, change the angle θ1according to the law:
| θ1=And[1-(α/αmax)(1-A/θ1c)]-1. | (5) |
Thus corners θ1and θ2will be connected by the relation:
| θ2=[θ1(1-2kθ1)-A]/2kθ1. | (6) |
Here k=(1-A/θ1 c)/amaxAnd=[1+l/p], V=2l/R and does not depend on the wavelength RL, θmis the Bragg angle of the crystal monochromators. In the case of asymmetric reflex monochromator 2 R=R0/b1(θm)+l0+htgθm, R0- the distance between the radiation source and the first crystal of the monochromator 2, l0- the distance between the monochromator 2 and the focusing mirror 4, h - distance between the guide horizontal movement of the monochromators 2 and 3, b1the asymmetry factor 2:
| b1(θm)=sin(θm+ϕ1)/sin(θm-ϕ1), | (7) |
where ϕ1- the angle of the reecting planes to the surface of the crystal-monochromator M1.
The method of controlling a corner on what Ozanam x-ray beam using a serial reflect pre monochromatizing beam of synchrotron radiation from the two mirrors, with a cylindrical and flat surfaces and rotation of the second mirror around an axis normal to the plane of the scattering of x-rays, characterized in that the produce rotation of the first mirror about an axis normal to the plane of the scattering of x-rays, and the angle θ1between the beam and the first mirror, and the angle θ2between the beam and the second mirror connected by the relation
θ2=[θ1(1-2kθ1)-A]/2kθ1,
k=(1-A/θ1 c)/αmax, A=B[1+l/p], b=2l/R, αmax=2(θ2 c-θ1 c),
where k and A are parameters dependent on the beam energy, the radius of curvature of the cylindrical surface of the first crystal and the distance between the radiation source and the focusing mirror;
αmax- the maximum angle formed between the optical beam and the sample surface during the experiment;
θ1 cand θ2 crespectively the values of the critical angles of total external reflection for the first (focusing) and second (flat) mirrors;
l is the distance between the first (focusing) mirror and the center of the field of illumination;
R - the distance from the x-ray source to the focusing mirrors;
R is the radius of the focusing mirrors.