Hiromi Hamanaka

Development of an in-air high-resolution PIXE system

Abstract A compact wavelength-dispersive crystal spectrometer system has been developed for high-resolution PIXE experiments in atmospheric air. A sample target placed in the air is irradiated with an external beam of protons. X-rays are diffracted with a flat analyzing crystal and detected with a position-sensitive proportional counter. Nearly all of the X-ray path from the target to counter is enveloped with a polyethylene bag filled with helium gas. The lowest X-ray energy detectable with this system is 0.9 keV and the angular resolution is 0.1° in the diffracting angle.

CHEMICAL STATE ANALYSIS IN AIR BY HIGH-RESOLUTION PIXE

Abstract A crystal spectrometer system was arranged at an external proton beam to measure the K X-ray spectra for various compounds of Al, Si, P and S at atmospheric pressure. Satellite structures of the Ks spectra caused by molecular-orbital splittings are well resolved. The results demonstrate that in situ chemical state analysis has now been possible using this in-air high-resolution PIXE system.

Damage formed by electron cyclotron resonance plasma etching on a gallium arsenide surface

Radiation damage induced on a gallium arsenide surface by electron cyclotron resonance (ECR) plasma etching is studied. The number of displaced atoms (displaced atom density) formed by exposure to ECR plasma is determined quantitatively by Rutherford backscattering spectrometry aligned spectra. The density increases with increasing microwave power. The amount of increase of displaced atom density from the undamaged virgin surface ΔDda is 2.9×1015 and 4.4×1015 atoms/cm2 at microwave power of 500 W (ion current density, Ii: 0.80 mA/cm2) and 800 W (Ii: 2.00 mA/cm2), respectively. The reflection high‐energy electron diffraction study shows that an amorphous layer is formed on the surface at 800 W (Ii: 2.00 mA/cm2). The effect of bias power and chamber pressure on the damage is also studied. The increase of damage (ΔDda: 3.2×1015 atom/cm2) from ECR plasma etching with an rf bias of 15 W is less by a factor of 2 than damage of reactive ion etching (ΔDda: 6.9×1015 atom/cm2) when compared at an ion current densit...

Chemical shift measurements of PIXE spectra using a position-sensitive crystal spectrometer

Abstract The in-air high-resolution PIXE system composed of a flat analyzing crystal and a position-sensitive proportional counter was applied to measure line shifts of Si Kα and P Kα X-rays from various samples induced by an external proton beam. Line shifts that reflect chemical environments of atoms in target samples were determined with the precision of 0.1 eV. The utility of the method for chemical state analysis of minor elements down to the order of 0.1% was demonstrated.

Fabrication and propagation characterization of As2S8 chalcogenide channel waveguide made by UV irradiation annealing

Changes in the refractive index of amorphous chalcogenide As2S8 films upon ultraviolet (UV) exposure and annealing at different temperatures are investigated in detail, indicating an index contrast of the order of 10(-2) in the As2S8 channel waveguide. An As2S8 channel waveguide is fabricated using UV well irradiation and then annealing near the glass transition temperature and shows a low propagation loss of 0.76 dB/cm and good propagation characterization at the 1310 nm guided mode.

Recovery of refractive-index profiles of planar graded-index waveguides from measured mode indices : an iteration method

An iteration method for calculating refractive-index profiles of graded-index waveguides from measured effective indices is presented. The refractive-index profiles recovered from the effective indices for the exponential function indicate that the accuracy of this method is better than ±10−4. We apply this method to Ti in-diffused Fe2O3–LiNbO3 and two-step ion-exchanged glass waveguides and obtain a good agreement between the theoretical and the experimental values.

Quantitative analysis of phosphorus in amorphous silicon using PIXE with a crystal spectrometer and PIPC

Abstract A PIXE (particle induced X-ray emission) method for analyzing impurities in solid materials was developed using a crystal spectrometer combined with a position sensitive proportional counter (PSPC). Numerical expressions for quantitative analysis of impurities by this method are established. This technique was applied to the nondestructive measurement of P in a-Si matrix. The concentration of P obtained in this method is 0.717%, which is consistent with the value of 0.68% deduced from the Auger electron spectroscopy.

HIGH RESOLUTION PIXE USING CRYSTAL SPECTROMETER COMBINED WITH POSITION SENSITIVE DETECTORS

We describe characteristics of high-resolution, wavelength-dispersive crystal spectrometers equipped with a different type of position sensitive X-ray detectors: PSPC, CCD, IP and MCP. Utilities of these position sensitive spectrometers in PIXE experiments are demonstrated by referring several recent topics of elemental analysis, chemical state analysis and a study on sample charging.

High-resolution PIXE with crystal spectrometer and position-sensitive proportional counter

Abstract A crystal spectrometer combined with a position-sensitive proportional counter was developed for analysing particle-induced X-rays. Three satellite lines (KL 0 , KL 1 , and KL 2 ) of Si K α X-rays produced by 1.5 MeV H + ion bombardment were well resolved. Energy resolutions of 3 and 30 eV are obtained, respectively, for Si K X-rays (1.74 keV) and Cr K α1 X-rays (5.414 keV). This method is expected to give a high-resolution PIXE of reasonable efficiency with low background or high detection limit, especially, for analysing light-element impurities in heavy-element matrix, and also to be useful for studies of ion-atom collisions, such as bremsstrahlung production and chemical effects in ion-atom collisions.

Rapid chemical state analysis by a highly sensitive high-resolution PIXE system

Abstract We have developed a crystal spectrometer system for rapid chemical state analysis by external beam particle induced X-ray emission. The system consists of a flat single crystal and a five-stacked position-sensitive proportional counter assembly. Chemical state analysis in atmospheric air within several seconds to several minutes is possible. A mechanism for time-resolved measurements is installed in the system. Performance of the system is demonstrated by measuring the time-dependence of chemical shifts of sulfur Kα1,2 line from marine sediment and aerosol samples.