On the 6895.5 Å and 8937.0 Å Bands of N2

A new low-lying 1Σ_g ⁺ state of the nitrogen molecule was recently predicted from ab initio calculations of the first 102 states which result from nitrogen atoms in the ⁴S, ²D and ²P states (1). The calculated spectroscopic constants for this new state seemed to fit well with the ones that could be estimated from the unidentified bands at 6895.5 Å and 8937.0 Å reported by Lofthus (2,3). Since spectrograms taken at moderate resolution already were available in the wavelenght region of interest, no new experiments at high resolution were initiated and a search for these bands was made. It was soon found that the wave numbers listed by Lofthus to a certain extent coincided with the listings given by Dieke and Heath (4) for the ^OP₁₂ and ^OP₂₃ satellite branches of the (1, 0) and (3, 0) bands of the B ³Σ_g - A ³Σ_u ⁺ transition of N₂. No other bands which could be related to the predicted ¹Σ_g ⁺ state were found in this region.     

Über die Struktur der CH-Bande 3143 Å und einer neuen NH-Bande 2530 Å

Zeitschrift für Physik A Hadrons and nuclei - Für die Anregung des CH-Bandensystems eignet sich eine kondensierte Funkenentladung zwischen Kohle- und Wolframelektroden in der...     

The 2175 Å interstellar extinction feature

The study of cosmic dust has become a central problem in modern astrophysics, its presence being recognized as a controlling feature in many diverse astrophysical processes. Yet, for over 20 years, a major piece of spectroscopic evidence relating to the physical nature and composition of interstellar dust has defied explanation, remaining a matter of extreme controversy, standing in the way of a full understanding of the nature of these small grains of cosmic matter. Here I review the observational properties of the ultraviolet 2175 Å interstellar extinction feature, the constraints that these place upon its physical interpretation, and the various extinction mechanisms and carrier materials that seek to explain it. The solution to the problem of the 2175 Å feature challenges both solid-state physics and astronomy, representing a unique opportunity for collaboration between these two sciences.     

Ti-pumped Mo X-ray laser at 24 Å

We propose using the Ti XXI He- emission line to resonantly photo-pump Li-like Mo (Z=42) and produce lasing on several n=5 n=4 transitions near 24 Å. The continuum emission from Ti photoionizes the Mo to the Li-like isoelectronic sequence. Gains of 1–2 cm^–1 are calculated on these lines before the inclusion of Stark broadening which lowers the gain by as much as a factor of two.     

Pressure broadening of methane lines in the 6190Åand 6825Åbands at room and low temperatures

Measurements of pressure broadened half-widths have been performed for one vibration-rotation line in the 6190Åmethane band and one vibration-rotation line in the 6825Åmethane band. Self-, nitrogen-, hydrogen- and helium-broadening have been measured over a temperature range of 77–295 K. Pressure broadening coefficients and temperature dependence indices have been obtained for each line and broadening gas.     

Lasing at 139 Å in nickel-like silver plasmas

Today, one of the key applications for X-ray Lasers is ICF-relevant plasma density diagnostics through interferometry techniques. Due to the peak reflectivity of the involved Mo/Si multilayer optics, the CEA/DAM studies have been focused on collisionnally excited population inversions in Ni-like silver plasmas. In order to optimize their X-ray output at 139 Å, various configurations have been investigated. One of them has recently been demonstrated at the P102 facility and has allowed 10¹¹ photons per pulse to be delivered, i.e. 2 μJ in 7 ps.     

Ar ion laser pumped dye-laser emission to 9500 Å

CW dye laser emission has been observed up to 9500 Å by using an Ar ion laser-pumped jet-stream dye laser. Peak powers as high as 300 mW were obtained around 8600 Å at a pump power of 4.4W.