Development of the Soft X-ray AGM-AGS RIXS beamline at the Taiwan Photon Source.

We report on the development of a high-resolution and highly efficient beamline for soft X-ray resonant inelastic X-ray scattering (RIXS) located at the Taiwan Photon Source. This beamline adopts an optical design that uses an active grating monochromator (AGM) and an active grating spectrometer (AGS) to implement the energy compensation principle of grating dispersion. Active gratings are utilized to diminish defocus, coma and higher-order aberrations, as well as to decrease the slope errors caused by thermal deformation and optical polishing. The AGS is mounted on a rotatable granite platform to enable momentum-resolved RIXS measurements with scattering angles over a wide range. Several high-precision instruments developed in-house for this beamline are described briefly. The best energy resolution obtained from this AGM-AGS beamline was 12.4 meV at 530 eV, achieving a resolving power of 4.2 × 104, while the bandwidth of the incident soft X-rays was kept at 0.5 eV. To demonstrate the scientific impact of high-resolution RIXS, we present an example of momentum-resolved RIXS measurements on a high-temperature superconducting cuprate, i.e. La2-xSrxCuO4. The measurements reveal the A1g buckling phonons in superconducting cuprates, opening a new opportunity to investigate the coupling between these phonons and charge-density waves.

Voiding urosonography with second-generation ultrasound contrast versus micturating cystourethrography in the diagnosis of vesicoureteric reflux.

Vesicoureteric reflux has been associated with paediatric urinary tract infection. Fluoroscopic micturating cystourethrography (MCU) has been the gold standard of diagnostic test for decades; however, it has been criticized owing to its lower detection rate and radiation dose to children. Therefore, new radiation-free reflux imaging modalities have been developed, in which ultrasound-based contrast-enhanced voiding urosonography (ceVUS) is a good example. However, ultrasonography has been considered as an operator-dependent examination. Therefore, our study aimed to examine the inter-observer agreement of this sonographic technique, which has not been evaluated before. Moreover, the second-generation ultrasound contrast SonoVue has been recently marketed, and the data on its efficacy on intravesical use in ceVUS is relatively scarce. Thus, we also aimed to investigate the diagnostic performance and safety profile of SonoVue-enhanced VUS in the diagnosis of vesicoureteric reflux. Our prospective comparative study compared the diagnostic performance of ceVUS with MCU in young children presenting with first episode of urinary tract infection. We performed sequential ceVUS and MCU examinations in 31 patients (62 pelvi-ureter units). Perfect inter-observer agreement (Cohen's kappa statistics = 1.0, p < 0.001) was achieved in ceVUS, suggesting its good reliability in reflux detection and grading. Using MCU as reference, ceVUS had 100 % sensitivity and 84 % specificity and carried higher reflux detection rate than MCU (p < 0.001). There was no complication encountered. Conclusion: Voiding urosonography is a reliable, sensitive, safe and radiation-free modality in the investigation of vesicoureteric reflux in children. It should be incorporated in the diagnostic algorithm in paediatric urinary tract infection.

Highly efficient beamline and spectrometer for inelastic soft X-ray scattering at high resolution.

The design, construction and commissioning of a beamline and spectrometer for inelastic soft X-ray scattering at high resolution in a highly efficient system are presented. Based on the energy-compensation principle of grating dispersion, the design of the monochromator-spectrometer system greatly enhances the efficiency of measurement of inelastic soft X-rays scattering. Comprising two bendable gratings, the set-up effectively diminishes the defocus and coma aberrations. At commissioning, this system showed results of spin-flip, d-d and charge-transfer excitations of NiO. These results are consistent with published results but exhibit improved spectral resolution and increased efficiency of measurement. The best energy resolution of the set-up in terms of full width at half-maximum is 108 meV at an incident photon energy tuned about the Ni L3-edge.

Observation of new Rydberg series in the many-electron transition region of N2.

Fluorescence excitation spectra produced through photoexcitation of N(2) using synchrotron radiation in the spectral region between 50 and 62.5 nm have been obtained with a resolution of 0.004 nm. A broadband detector (in the 115-180 nm region) was employed to monitor fluorescence originated from neutral excited atomic nitrogen fragments which are produced through direct dissociation processes and predissociation from the well-known many-electron excited Rydberg states. We have identified a new Rydberg series (2 (2)Π(g)) 4sσ, a better resolved Rydberg (D (2)Π(g)) npσ series, and also the prominent Codling series converging to the D (2)Π(g), and C (2)Σ(u)(+) states of N(2)(+), respectively. By normalizing our relative fluorescence intensities to previously measured absolute fluorescence cross-section data we obtain the cross-section data of undispersed fluorescence in the 115-180 nm region. The fluorescence quantum yields for the present photodissociative excitation processes are found to be less than 0.05. The present results may provide important data for our understanding of competitions among the various decay channels of the many-electron transition states of N(2).

Experimental verification of strong rotational dependence of fluorescence and predissociation yield in the b1Πu(v = 1) level of 14N2.

New, rotationally resolved fluorescence-excitation spectra confirm coupled-channel Schrödinger-equation predictions of strong rotational dependence of the fluorescence and predissociation yields in the b(v = 1) level of (14)N(2).

Persistent sciatic artery complicated by aneurysm formation and thrombosis.

A persistent sciatic artery is a rare embryological anomaly. We report a case of a persistent sciatic artery with aneurysm formation and thrombosis in a patient with rheumatoid arthritis/systemic lupus erythematosus overlap syndrome and Raynaud's phenomenon. The diagnosis and complete, accurate evaluation of the arterial anatomy of the lower limb were achieved using computed tomographic angiography.