X-ray charge densities and chemical bondingby P. Coppens

Extragalactic H2O masers and X-ray absorbing column densities

Having conducted a search for the λ∼1.3 cm (22GHz) water vapor line towards galaxies with nuclear activity, large nuclear column densities or high infrared luminosities, we present H2O spectra for NGC2273, UGC5101, and NGC3393 with isotropic luminosities of 7, 1500, and 400 L⊙. The H2O maser in UGC5101 is by far the most luminous yet found in an ultraluminous infrared galaxy. NGC3393 reveals th...

Charge-coupled device area x-ray detectors

Charge-coupled device ~CCD! area x-ray detector technology is reviewed. CCD detectors consist of a serial chain of signal components, such as phosphors, fiber optics or lenses, image intensifiers and the CCD which serve to convert the x-ray energy to light or electron-hole pairs and to record the spatially resolved image. The various combinations of components that have been used to make CCD de...

Chemical characterization and X-ray absorption spectroscopy

A rapid progress in the theoretical developments based on modulations of absorption cross section due to single and multiple scattering of an electron emitted from an inner shell by X-rays impinging on the target atom to understand the EXAFS and XANES in recent years and harnessing of the highly powerful synchrotron radiation source for the X-rays have bestowed immense capability on X-ray absor...

Energy dispersive x-ray diffraction of charge density waves via chemical filtering

X-ray Fluctuation Power Spectral Densities of Seyfert 1 Galaxies

By combining complementary monitoring observations spanning long, medium and short time scales, we have constructed power spectral densities (PSDs) of six Seyfert 1 galaxies. These PSDs span &4 orders of magnitude in temporal frequency, sampling variations on time scales ranging from tens of minutes to over a year. In at least four cases, the PSD shows a ”break,” a significant departure from a ...