C.W. Wang

Effect of carbon sources on silicon carbon nitride films growth in an electron cyclotron resonance plasma chemical vapor deposition reactor

Abstract The effect of carbon source on SiCN film growth was studied in an electron cyclotron resonance plasma chemical vapor deposition reactor. The growth characteristics of CH4, C2H2 and CH3NH2 were examined with and without H2 addition during growth. The results indicated that SiCN films were deposited successfully using CH4 with H2 addition as well as using CH3NH2 both with and without H2 addition. (Si; C) and N composition ratios of the films thus deposited were around 0.75. Carbon was hardly incorporated into the films when deposited using C2H2 as the source gas regardless of H2 addition during growth. Among the three source gas studied, CH3NH2 was the most effective for the SiCN films growth. Spectroscopic study of the gas phase species during growth and discussion on the growth phenomena are presented in this paper.

L x-ray production in lanthanide elements by 1 - 5 MeV helium ions

L x-ray production in and was measured for bombardment in the energy range 1 - 5 MeV. Very thin target foils were used, and x-ray yields were measured simultaneously with elastically scattered ions. The L-shell and individual and production cross sections and their ratios were extracted. These cross sections are compared to the results of the ECPSSR theory (energy-loss and Coulomb deflection effects, perturbed stationary state approximation with the relativistic correction), its united-atom (UA) extension UA-ECPSSR and the UA-ECPSSR-MI, which also accounts for multiple ionization (MI). With a few exceptions, the standard ECPSSR appears to be better than its modifications when and ratios are analysed. and and total L x-ray production cross sections, however, are in the best overall agreement with the UA-ECPSSR-MI theory.

External-beam PIXE analysis of ancient chinese coins

Abstract The external-beam PIXE (proton induced X-ray emission) method has been applied for the determination of the elemental composition of ancient Chinese coins in the Ching Dynasty (AD 1644–1911). The X-ray emission measurements for the samples bombarded with 3 MeV protons from 9SDH-2 Pelletron tandem accelerator were carried out with the use of a 30 mm 2 × 5 mm Ge(Li) detector. The external-beam milliprobe designed for the experiment is essentially the same as the one used in our previous works. Variations of composition for more than 23 samples covering a time period of about three hundred years were examined. Results on the contents of principal component elements (Cu, Zn, Pb, Sn, Sb, Fe, Ni and As) are presented and discussed.

PIXE ANALYSIS OF ANCIENT CHINESE CHANGSHA PORCELAIN

Abstract In this work, proton induced X-ray emission (PIXE) method was applied for the analysis of ancient Chinese Changsha porcelain produced in the Tang dynasty (AD 618–907). A collection of glazed potsherds was obtained in the complex of the famous kiln site at Tongguan, Changsha city, Hunan province. Studies of elemental composition were carried out on ten selected Changsha potsherds. Minor and trace elements such as Ti, Mn, Fe, Co, Cu, Rb, Sr, and Zr in the material of the porcelain glaze were determined. Variation of these elements from sample to sample was investigated. Details of results are presented and discussed.

Atomic K shell ionization of Mn, Fe, Ni, Cu and Zn by carbon ions

Abstract Yields of the K X-rays and elastic scattering particles induced by carbon ion impact on thin targets of Mn, Fe, Ni, Cu and Zn have been measured simultaneously at incident energies ranging from 3.0 to 9.0 MeV with steps of 0.6 MeV. Experimental K shell X-ray production cross sections are reported and compared to the first-order Born and the ECPSSR theories, as well as to the results of previous measurements. The ECPSSR theory gives results much closer to the experimental data except at low energies, while the first-order Born approximation overestimates the data by more than a factor of 6 at all energies. In addition, the data obtained for the K β K α intensity ratio are presented and discussed.

A PIXE study of vitrification of carnation in vitro culture

PIXE (Proton Induced X-ray Emission) is a well-known method for elemental analyses of specimens in applied studies. In this paper, we report results of an application of PIXE in trace-element analysis of normal and vitrified carnations in vitro culture. Experiments were performed to study the vitrification in connection with the trace elements in carnation tissues. About two hundred PIXE spectra were obtained from seventy samples with an irradiation of 3 MeV protons from the NEC 9SDH-2 Pelletron tandem accelerator. From the PIXE analysis we determined the trace element composition of normal and vitrified carnations. Our results indicate that there is a significant change of K, Ca, Fe and Zn contents in the vitrification process.

Application of PIXE for elemental analysis of ancient Chinese artifacts

Abstract Proton induced X-ray emission (PIXE) is a well-known method for elemental analysis in many different specimens for various applied studies. In this paper, we report an application of PIXE analysis for a series of ancient Chinese coins from the Tang Dynasty to the Ming Dynasty (AD 618–1679). Ninety-six PIXE spectra were obtained from forty-eight samples of the ancient coins with the use of a Ge(Li) X-ray detector. On each sample two spots at different positions on the flat surface were irradiated per run by 3 MeV protons from a NEC 9SDH-2 pelletron tandem accelerator. The principal component elements (Cu, Pb, Sn and Zn) and others (Fe, Sb, Ni and As) were determined for the analyzed coins. Variations in composition with a time span of about one thousand years for the examined coins were observed. The results are presented and aspects of the evolution of Chinese metallurgy in casting coins are discussed.

Lithium-7 ion induced K X-ray production cross sections of Ti, Cu, Se, and Ag in the energy range 3.0–10.0 MeV

Emissions of characteristic K X-rays and elastic scattering particles induced by 7Li ions impacted on Ti, Cu, Se, and Ag (Z = 22–47) were measured at energies 3.0–10.0 MeV in steps of 0.7 MeV. Experimental K X-ray production cross sections and the kβkα intensity ratios are presented. The measured production cross sections for these four elements show a rapid decrease as the atomic number Z increases from 22 to 47. The results are compared with the predictions of the first-order Born approximation, the ECPSSR theory and the 1sσ molecular-orbital theory (MO). It was found that the ECPSSR and MO theories give better predictions to the data in the investigated energy range. Agreement between the ECPSSR and MO theories and the experiment is reasonably good, except that for Ag the ECPSSR and MO theories seem to mildly underestimates the data at lower energies.

Atomic K shell ionization by 3.0–15 MeV oxygen ions for selected elements between Ti and In

Abstract The K-shell X-rays and elastic scattering particles induced by 3.0–15 MeV oxygen ions were measured simultaneously for selected elements between Ti and In (in the atomic number range Z = 22–49). Experimental K X-ray production cross sections as a function of projectile energy in this energy interval in steps of 0.6 MeV are reported. Results of measurement are compared with the predictions of the first Born, the ECPSSR and the MO ionization theories. The first Born and the ECPSSR theories give about the same trends of energy dependence of cross sections. However, the first Born approximation overestimates the experimental data by about a factor of 20 throughout the investigated energy range. The ECPSSR prediction shows a better agreement with the experiment, except at lower energies, where the MO theory matches the data slightly closer.

Charge state dependence of copper L-shell x-ray production by 4 - 14 MeV oxygen ions

Charge state dependence of L-shell x-ray production cross sections in bombarded by 4 - 14 MeV ions with charge states from q = 3+ to 8+ was measured using a Si(Li) x-ray detector with a resolution of 96 eV at 1 keV. An ultra-thin copper foil was used to ensure single-collision conditions. The data for the total L x-ray production cross sections are compared to the predictions of the first Born and the ECPSSR calculations for L-shell ionization converted to x-ray production cross sections using a single-hole fluorescence yield. Except at the lowest projectile velocity, the ECPSSR theory gives satisfactory agreement with the data while the first Born theory overpredicts all the data in the investigated energy range by almost two orders of magnitude. Measurements of the charge state dependence of the target L-shell x-ray production cross sections allowed the separate contributions of the electron capture (EC) and the direct ionization (DI) to the inner-shell ionization to be determined. The EC contributions were extracted from the x-ray measurements with two, one, and no K-shell vacancies in the oxygen ions. These EC cross sections are compared with the results of an OBK approximation and the ECPSSR theory, and found to be significantly smaller than both EC calculations.