On the difference between the X-ray selected and the radio selected BL Lac objects in the near infrared

✦ Synopsis

By using results from the 2MASS observation, the differences between the X-ray selected BL Lac objects (XBLs) and the radio selected ones (RBLs) in the near infrared are discussed in this paper. It is found that, statistically, the RBLs have redder near infrared colors and steeper spectral indices in the near infrared than XBLs, whereas the XBLs have more influences from their host galaxies than the RBLs. It is also seen that the RBLs have much brighter luminosity in the near infrared than the XBLs. In addition, the high polarization characteristics are found in common for RBLs, but not for XBLs.

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