Using recently derived-values of the water vapor dimer spectral absorption cross section we calculate the water vapor dimer contribution to the clear sky absorption of solar radiation. We consider the water dimer concentrations deduced from local equilibrium thermodynamics, and we account for the overlap of water vapor dimer and monomer absorption bands. We estimate that water vapor dimer contr...

Results from previous laboratory experiments indicate that both the protonated water dimer H3O(H2O), and molecular cluster-ions, X(H2O)n absorb infra-red (IR) radiation in the water vapour continuum region between 4-14μm (2500-714cm). Protonated water clusters are a common species of atmospheric molecular cluster-ion, produced by cosmic rays throughout the troposphere and stratosphere. Under cl...

A new kind of discrete tomography problem is introduced: the reconstruction of discrete sets from their absorbed projections. A special case of this problem is discussed, namely, the uniqueness of the binary matrices with respect to their absorbed row and column sums when the absorption coefficient is = log((1+√5)/2). It is proved that if a binary matrix contains a special structure of 0s and 1...

At redshifts z2, most of the baryons reside in the smooth intergalactic medium which is responsible for the low column density Lyα forest. This photoheated gas follows a tight temperature-density relation which introduces a cut-off in the distribution of widths of the Lyα absorption lines (b-parameters) as a function of column density. We have measured this cut-off in a sample of nine high reso...

We have previously demonstrated a pulsed direct detection IPDA lidar to measure range and the column concentration of atmospheric CO2. The lidar measures the atmospheric backscatter profiles and samples the shape of the 1,572.33 nm CO2 absorption line. We participated in the ASCENDS science flights on the NASA DC-8 aircraft during August 2011 and report here lidar measurements made on four flig...

The limiting uncertainty in recent high accuracy measurements of the mass attenuation coefficient is the measurement of the integrated column density. An improvement in the design of the absorption foil holder is described which reduces the integrated column density uncertainty. The new design allows the edges of the foil to be more accurately mapped by the X-ray beam by reducing the largest so...

We present new, high angular resolution (∼0. ′′ 22) MERLIN observations of neutral hydrogen (H i) absorption and λ21-cm radio continuum emission across the central ∼900 parsecs of the ultraluminous infrared galaxy, Arp220. Spatially resolved H i absorption is detected against the morphologically complex and extended λ21-cm radio continuum emission, consistent with two coun-terrotating disks of ...

We have searched for molecular absorption lines at millimeter wavelengths in eleven gravitational lens systems discovered in the JVAS/CLASS surveys of flat spectrum radio sources. Spectra of only one source 1030+074 were obtained in the 3-, 2and 1.3-millimeter band at the frequencies corresponding to common molecular transitions of CO and HCO as continuum emission was not found in any of the ot...

This paper provides a general reference for deriving the ionizations and metal abundances for absorption-line clouds in photoionization equilibrium with a QSO spectrum. The results include a quantitative assessment of the theoretical uncertainties and Ðrm lower limits on the metallicities when no ionization constraints are available. The calculations applied to the best available column densiti...