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We report generation of directional far-infrared emission between Rydberg states of NO in the gas phase initiated by the absorption of black body radiation at room temperature. All the transitions detected are assignable to the nf → (n − 1)g and n′g → (n′ − 1)f transitions. The longest wavelength observed in the present experiment was ~ 112 µm (2.7 THz) which corresponds to the 14f → 13g transition. The laser-prepared population in the 14s and 15s states is transferred to the 13f and 14f states located energetically higher, respectively, which generates the subsequent emission of 13f → 12g at ~ 88 µm and 14f → 13g at ~ 112 µm. Collisions of Rydberg molecules with the surrounding ground state molecules are considered to responsible for the upward population flow. The population in the 14p and 15p states is transported to the 13f and 14f states located energetically lower, respectively, which gives rise to the subsequent emission of 13f → 12g at ~ 88 µm and 14f → 13g at ~ 112 µm. [ABSTRACT FROM AUTHOR]

The bulk of the present-day stellar mass was formed in galaxies when the universe was less than half its current age (i.e., 1 ≲ z ≲ 3 ). While this likely marks one of the most critical time periods for galaxy evolution, we currently do not have a clear picture on the radial extent and distribution of cold molecular gas and associated star formation within the disks of galaxies during this epoch. Such observations are essential to properly estimate the efficiency at which such galaxies convert their gas into stars, as well as to account for the various energetic processes that govern this efficiency. Long-wavelength (i.e., far-infrared–to–radio) observations are critical to penetrate the high-levels of extinction associated with dusty, infrared-bright galaxies that are driving the stellar mass assembly at such epochs. In this article, we discuss how the next-generation Very Large Array will take a transformative step in our understanding of galaxy formation and evolution by delivering the ability to simultaneously study the relative distributions molecular gas and star formation on sub-kpc scales unbiased by dust for large populations of typical galaxies in the early universe detected by future far-infrared space missions. [ABSTRACT FROM AUTHOR]

We studied the far-infrared emission spectrum resulting from recombination of an electron with an ionized impurity of As and Sb in germanium under impact ionization at liquid, helium temperatures. The emission peaks at the position corresponding to the transition from the 2 p excited state to the ground state. This observation indicates that recombination occurs through the capture by the excited states of the donor impurity, which is consistent with the cascade trap model. The intensity of emission radiation is of the order of 10 watts for the excitation power of about one watt, which implies a dominant process of recombination to be accompanied by phonon emission. [ABSTRACT FROM AUTHOR]