Hyperfine interactions of implanted nuclei in graphite observed by low temperature nuclear orientation

✦ Synopsis

Pure nuclear electric quadrupole interaction of ion-implanted 203Hg and lBB Ir in Highly Oriented Pyrolytic Graphite layers has been observed in low temperature nuclear orientation experiments. The electric field gradients at the nuclear sites were found ~o be positive, with values of +0.79(17)xI0 19 v/cm 2 (vQ=0.66(l4) GHz) for 03Hg and +0.788(40)xl0 19 V/cm 2 (vQ=0.987(40) GHz) for lBB Ir . At 4 mK, the anisotropies in the directional distribution of .-rays from these isotopes were saturated, but only at 35.2 (2.4) % for 203Hg , respectively 8.59(18) % for l8B Ir , of the expected maximum value.

Oxygen interaction of CdS-based gas sens

Oxygen interaction of CdS-based gas sensors with different stoichiometric compositions was studied by X-ray photoelectron spectroscopy (XPS) and thermal-desorption mass spectroscopy observations combined with conductivity measurements. Three different types of film with different atomic ratios of Cd/S were used in the study of oxygen chemisorption in a low-temperature range between 300 and 570 K. Spray pyrolysis was used for the deposition of the films on glass substrates; XPS and energy dispersive spectroscopy of X-ray together with atomic force microscopy and scanning electron microscopy were used for the characterization of the composition and structure of the films. It was possible to distinguish different temperature ranges for the thermal desorption of the different adsorbed oxygen species. A comparison of the data from XPS and mass-spectroscopy observations with conductance measurements allows to conclude that metallic surface atoms are responsible for different interactions of oxygen species with CdS surfaces.

📂 Article 📅 1995 🏛 Elsevier Science 🌐 English ⚖ 379 KB