single-valence electron atoms are an important class of atoms. their oscillator strengths are their important properties. knowing the oscillator strengths one can easity calculate the transition probabilities of the spectral lines and hence the lifetimes of energy levels of most atoms. the oscillator strengths of the spectral lines of most atoms are not knoen with sufficient accuracy due to the...

It is possible, by selective excitation of homogeneously broadened lines, to produce response signals, which are orders of magnitude narrower than the original lines. The new type of echo, which allows detecting such signals, and the formalism, useful for understanding the phenomenon, as well as the experimental examples from NMR spectroscopy are presented. Long-lived partial NMR echo in solids...

It is widely accepted that active galactic nuclei (AGN) are hosting a supermassive black hole in their center. The supermassive black hole is actively fueled by surrounding gas through an accretion disk, which produces a broad band continuum (from X-ray to radio emission). The hard photons from the accretion disk create the photoionized plasma around the central black hole, which emits a number...

Shift and broadening of isolated neutral helium lines 7281 angstroms (2(1)P-3(1)S), 7065 angstroms (2(3)P-3(3)S), 6678 angstroms (2(1)P-3(1)D), 5048 angstroms (2(1)P-4(1)S), 4922 angstroms (2(1)P-4(1)D), and 4713 angstroms (2(3)P-4(3)S) in a dense plasma are investigated. Based on a quantum statistical theory, the electronic contributions to the shift and width are considered, using the method ...

The line profiles from rotating neutron stars are affected by a number of relativistic processes such as Doppler boosts, strong self-lensing, frame-dragging, and the differential gravitational redshift arising from the stellar oblateness. In this Letter, we calculate line profiles taking into account the first two effects, which is accurate for rotation rates less than the breakup frequency. We...

We analyze in detail the seismic vibrations generated by trains, measured at distance from the track with high sensitivity broadband sensors installed for the AlpArray project. The geometrical restrictions of the network resulted in a number of instruments deployed in the vicinity of railway lines. On seismic stations within 1.5 km of a railway, we observe characteristic seismic signals that we...