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Beam-induced damage on diffractive hard X-ray optics.

Nygård K, Gorelick S, Vila-Comamala J, Färm E, Bergamaschi A, Cervellino A, Gozzo F, Patterson BD, Ritala M, David C - J Synchrotron Radiat (2010)

Bottom Line: The issue of beam-induced damage on diffractive hard X-ray optics is addressed.For this purpose a systematic study on the radiation damage induced by a high-power X-ray beam is carried out in both ambient and inert atmospheres.Diffraction gratings fabricated by three different techniques are considered: electroplated Au gratings both with and without the polymer mold, and Ir-coated Si gratings.

View Article: PubMed Central - HTML - PubMed

Affiliation: Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland. kim.nygard@psi.ch

ABSTRACT
The issue of beam-induced damage on diffractive hard X-ray optics is addressed. For this purpose a systematic study on the radiation damage induced by a high-power X-ray beam is carried out in both ambient and inert atmospheres. Diffraction gratings fabricated by three different techniques are considered: electroplated Au gratings both with and without the polymer mold, and Ir-coated Si gratings. The beam-induced damage is monitored by X-ray diffraction and evaluated using scanning electron microscopy.

No MeSH data available.


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SEM image of the Au grating (triangles in Fig. 5 ▶) after irradiation.
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fig6: SEM image of the Au grating (triangles in Fig. 5 ▶) after irradiation.

Mentions: Next, we consider the effect of different atmospheres and different types of gratings. This is presented in Fig. 5 ▶ as the normalized diffraction efficiency for pi/Au gratings in air and in vacuum as well as Au and Ir/Si gratings in air. From the data we make the following observations. (i) The use of a vacuum environment significantly improves the resistance of pi/Au gratings to X-rays, yielding the values ≃ 0.7 and N C ≃ 13 × 1017 photons mm−2. This observation conforms with previous studies of radiation damage in polymers, in which the use of an inert He atmosphere was found to slow down the radiation damage (Coffey et al., 2002 ▶). (ii) The removal of the polymer mold strongly increases the resistance to X-rays. For the Au gratings in air, we determine the values ≃ 0.9 and N C ≃ 21 × 1017 photons mm−2. This indicates that the beam-induced damage in the polymer-containing structures is mediated by the polymer mold. A hypothesis for this effect is as follows. The Au gratings consist of segmented Au lines (see Fig. 1 ▶). Consequently, the breaking of the interface between a segmented Au line and the plating base only induces a local defect (Fig. 6 ▶). However, if the polymer mold is present, a local defect induces mechanical stress, which in turn may induce more defects (cf. Fig. 4). (iii) The Ir/Si gratings are found to be resistant to hard X-rays. We observe no degradation of the Ir/Si gratings upon exposing them to N 0 ≃ 220 × 1017 photons mm−2 in air. We have verified this observation by SEM inspection of the Ir/Si grating after irradiation. We attribute this effect to the robust interface between Ir and Si, as obtained through atomic layer deposition of Ir (Vila-Comamala et al., 2009 ▶). This result demonstrates the benefits of combining a low-Z material template with a high-Z material coating: template materials such as Si or diamond show a good thermal conductivity and low thermal deformations, while coating materials such as Ir provide a high diffraction efficiency. Table 1 ▶ summarizes the fit parameters.


Beam-induced damage on diffractive hard X-ray optics.

Nygård K, Gorelick S, Vila-Comamala J, Färm E, Bergamaschi A, Cervellino A, Gozzo F, Patterson BD, Ritala M, David C - J Synchrotron Radiat (2010)

SEM image of the Au grating (triangles in Fig. 5 ▶) after irradiation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2964115&req=5

fig6: SEM image of the Au grating (triangles in Fig. 5 ▶) after irradiation.
Mentions: Next, we consider the effect of different atmospheres and different types of gratings. This is presented in Fig. 5 ▶ as the normalized diffraction efficiency for pi/Au gratings in air and in vacuum as well as Au and Ir/Si gratings in air. From the data we make the following observations. (i) The use of a vacuum environment significantly improves the resistance of pi/Au gratings to X-rays, yielding the values ≃ 0.7 and N C ≃ 13 × 1017 photons mm−2. This observation conforms with previous studies of radiation damage in polymers, in which the use of an inert He atmosphere was found to slow down the radiation damage (Coffey et al., 2002 ▶). (ii) The removal of the polymer mold strongly increases the resistance to X-rays. For the Au gratings in air, we determine the values ≃ 0.9 and N C ≃ 21 × 1017 photons mm−2. This indicates that the beam-induced damage in the polymer-containing structures is mediated by the polymer mold. A hypothesis for this effect is as follows. The Au gratings consist of segmented Au lines (see Fig. 1 ▶). Consequently, the breaking of the interface between a segmented Au line and the plating base only induces a local defect (Fig. 6 ▶). However, if the polymer mold is present, a local defect induces mechanical stress, which in turn may induce more defects (cf. Fig. 4). (iii) The Ir/Si gratings are found to be resistant to hard X-rays. We observe no degradation of the Ir/Si gratings upon exposing them to N 0 ≃ 220 × 1017 photons mm−2 in air. We have verified this observation by SEM inspection of the Ir/Si grating after irradiation. We attribute this effect to the robust interface between Ir and Si, as obtained through atomic layer deposition of Ir (Vila-Comamala et al., 2009 ▶). This result demonstrates the benefits of combining a low-Z material template with a high-Z material coating: template materials such as Si or diamond show a good thermal conductivity and low thermal deformations, while coating materials such as Ir provide a high diffraction efficiency. Table 1 ▶ summarizes the fit parameters.

Bottom Line: The issue of beam-induced damage on diffractive hard X-ray optics is addressed.For this purpose a systematic study on the radiation damage induced by a high-power X-ray beam is carried out in both ambient and inert atmospheres.Diffraction gratings fabricated by three different techniques are considered: electroplated Au gratings both with and without the polymer mold, and Ir-coated Si gratings.

View Article: PubMed Central - HTML - PubMed

Affiliation: Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland. kim.nygard@psi.ch

ABSTRACT
The issue of beam-induced damage on diffractive hard X-ray optics is addressed. For this purpose a systematic study on the radiation damage induced by a high-power X-ray beam is carried out in both ambient and inert atmospheres. Diffraction gratings fabricated by three different techniques are considered: electroplated Au gratings both with and without the polymer mold, and Ir-coated Si gratings. The beam-induced damage is monitored by X-ray diffraction and evaluated using scanning electron microscopy.

No MeSH data available.


Related in: MedlinePlus