XPAD X-ray hybrid pixel detector for charge density quality diffracted intensities on laboratory equipment

Wenger, Emmanuel; Dahaoui, Slimane; Allé, Paul; Parois, Pascal; Palin, Cyril; Lecomte, Claude; Schaniel, Dominik

doi:10.1107/s2052520614017338

Cited by 12 publications

(10 citation statements)

References 25 publications

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“…The present study has demonstrated that a data correction is required for the IP reader to detect the weak reflection at this level. Several types of area detector, such as IPs, charge-coupled devices (CCD), pixel detectors etc., have been used for charge-density studies during the past couple of decades (Bolotovsky et al, 1995;Martin &Pinkerton, 1998;Wenger et al, 2014). Several types of data correction for charge-density studies, such as oblique incidence correction (Wu et al, 2002) and flat field correction (Bergamaschi et al, 2010;Thompson et al, 2011), have been developed and applied to actual data.…”

Section: Discussionmentioning

confidence: 99%

Structure factors and charge-density study of diamond at 800 K

Deguchi

Nishibori

2018

Acta Crystallogr Sect B

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The structure factors of diamond were determined by synchrotron radiation X-ray powder diffraction at 800 K at sin / 2.2 Å À1 reciprocal resolution. The structure factors were estimated using six powder profiles measured on beamline BL02B2 at SPring-8 (Hyogo, Japan). A high reciprocal resolution at sin / 2.2 Å À1 was required to reveal the temperature dependence of the charge density, due to the high Debye temperature of D = 1860 K of diamond. Wide 2 angle data with the highest counting statistics are crucial for accurate data analysis. The periodic noise of every six-pixel step was observed in the highest counting statistics imaging plate (IP) data scanned by a BAS2500 IP scanner. It was found that the noise originated from the six-sided polygonal mirror in the scanner. The intensity fluctuation at every six-pixel step was also found in the Fourier series expansion of the powder profiles. The ratio of the maximum fluctuation was estimated as 0.4% by summing all six-pixel step data. The powder profiles were corrected by multiplying the ratios. The intensity fluctuation in the background region was reduced to less than 50% of the uncorrected data. The weak 888 Bragg reflection, with an intensity of 0.005% of that of the 111 Bragg reflection at 800 K, was readily observed in the corrected data. Finally, the structure factors determined at 800 K were successfully applied to a charge-density study by multipole modelling. The reliability factors and multipole parameters at 800 K are in agreement with those at 300 K. The differences in the charge density at the bond midpoint and r 2 at the bondcritical point were less than 1% and 2%, respectively.

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Section: Discussionmentioning

confidence: 99%

Structure factors and charge-density study of diamond at 800 K

Deguchi

Nishibori

2018

Acta Crystallogr Sect B

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“…Re-collection and adjustment of the collection strategy to the new experimental conditions is somewhat time consuming and should be avoided if possible. With the newly introduced hybrid pixel area detectors, this contamination should no longer be problematic since these detectors are able to discriminate on photon energy and the given energy difference is most likely large enough (Wenger et al, 2014;Stalke, 2014). However, this needs to be experimentally validated.…”

Section: Introductionmentioning

confidence: 99%

An empirical correction for the influence of low-energy contamination

2015

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Low‐energy contamination caused by focusing multilayer optics has been known for a long time. So far, the only method to avoid this problem is attenuation by interposition of a low‐density material foil into the beam. However, attenuation lowers the intensity, which might be crucial, especially for charge density data collection, and is of course not possible for already measured data. In this article, an empirical correction is proposed as an alternative or addition. The low‐energy contamination mainly affects the reflections with indices 3h 3k 3l. In the program SADABS, a 3λ correction in analogy to the earlier 2/λ correction is now implemented. The correction factor can be determined from the model, but for most cases, a default value depending on the experimental settings is acceptable. Alternatively, the correction can be refined in SHELXL, similarly to a twin refinement. An investigation of several data sets collected with and without attenuation revealed that the empirical correction and attenuation lead to similar improvements. The empirical correction is of special interest for charge density investigations, where the loss of intensity could hinder the data collection up to very high resolution. Here, the improvements in the model, especially for the noise level of the residual density, are even more pronounced.

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“…This kind of detector may therefore be efficiently used to isolate single X-ray bunches from the pulse train of synchrotron radiation sources in stroboscopic pumpprobe measurements (Lauhé et al, 2012;Jacques et al, 2016). We implemented a hybrid pixel detector on our laboratory diffractometer, originally for the study of electric field-induced structural changes (Fertey et al, 2013), and recently also demonstrated its excellent potential for high-resolution X-ray diffraction studies (Wenger, 2015;Wenger et al, 2014). Here, we report on the extension of this setup to laser pump/X-ray probe time-resolved crystallography in the millisecond time scale.…”

Section: Introductionmentioning

confidence: 99%

In-house time-resolved photocrystallography on the millisecond timescale using a gated X-ray hybrid pixel area detector

Casaretto

Schaniel

Allé

et al. 2017

Acta Crystallogr Sect B

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With the remarkable progress of accelerator-based X-ray sources in terms of intensity and brightness, the investigation of structural dynamics from timeresolved X-ray diffraction methods is becoming widespread in chemistry, biochemistry and materials science applications. Diffraction patterns can now be measured down to the femtosecond time-scale using X-ray free electron lasers or table-top laser plasma X-ray sources. On the other hand, the recent developments in photon counting X-ray area detectors offer new opportunities for time-resolved crystallography. Taking advantage of the fast read-out, the internal stacking of recorded images, and the gating possibilities (electronic shutter) of the XPAD hybrid pixel detector, we implemented a laboratory X-ray diffractometer for time-resolved single-crystal X-ray diffraction after pulsed laser excitation, combined with transient optical absorption measurement. The experimental method and instrumental setup are described in detail, and validated using the photoinduced nitrosyl linkage isomerism of sodium nitroprusside, Na 2 [Fe(CN) 5 NO]Á2H 2 O, as proof of principle. Light-induced Bragg intensity relative variations ÁI(hkl)/I(hkl) of the order of 1%, due to the photoswitching of the NO ligand, could be detected with a 6 ms acquisition window. The capabilities of such a laboratory time-resolved experiment are critically evaluated.

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XPAD X-ray hybrid pixel detector for charge density quality diffracted intensities on laboratory equipment

Cited by 12 publications

References 25 publications

Structure factors and charge-density study of diamond at 800 K

Structure factors and charge-density study of diamond at 800 K

An empirical correction for the influence of low-energy contamination

In-house time-resolved photocrystallography on the millisecond timescale using a gated X-ray hybrid pixel area detector

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