Weak maser emission of methyl formate toward Sagittarius B2(N) in the Green Bank Telescope PRIMOS Survey

A non-LTE radiative transfer treatment of cis-methyl formate (HCOOCH3) rotational lines is presented for the first time using a set of theoretical collisional rate coefficients. These coefficients have been computed in the temperature range 5-30 K by combining coupled-channel scattering calculations with a high accuracy potential energy surface for HCOOCH3-He. The results are compared to observations toward the Sagittarius B2(N) molecular cloud using the publicly available PRIMOS survey from the Green Bank Telescope. A total of 49 low-lying transitions of methyl formate, with upper levels below 25 K, are identified. These lines are found to probe a presumably cold (~30 K), moderately dense (~1e4 cm-3) and extended region surrounding Sgr B2(N). The derived column density of ~4e14 cm-2 is only a factor of ~10 larger than the column density of the trans conformer in the same source. Provided that the two conformers have the same spatial distribution, this result suggests that strongly non-equilibrium processes must be involved in their synthesis. Finally, our calculations show that all detected emission lines with a frequency below 30 GHz are (collisionally pumped) weak masers amplifying the continuum of Sgr B2(N). This result demonstrates the importance and generality of non-LTE effects in the rotational spectra of complex organic molecules at centimetre wavelengths.Comment: 33 pages, 9 figures, accepted in The Astrophysical Journal (january 4 2014

Water pair potential of near spectroscopic accuracy. II. Vibration-rotation-tunneling levels of the water dimer

Contains fulltext : 14117.pdf (publisher's version ) (Open Access

Water pair potential of near spectroscopic accuracy. I. Analysis of potential surface and virial coefficients

Contains fulltext : 14099.pdf (publisher's version ) (Open Access

Underground tourist routes as an element of Poland’s cultural heritage

Underground tourist routes respond to current trends in museum development. They can be treated as interactive exhibitions focused primarily on the visitor. Former underground mines are also important elements of cultural heritage. They preserve mining equipment and traces of mining techniques. Through interactivity they can perform an educational function, presenting mining memorabilia and customs. Underground routes are also tourist destinations, attracting a significant number of visitors. The present study covered eight routes located in different regions of Poland. Their tourist value was assessed and tourists were asked to complete a survey regarding the routes. The significance of the mining heritage was described and evaluated. On this basis, the strengths and weaknesses of the underground mine routes as places of presentation of cultural heritage were identified. The sites surveyed are characterised by their high potential but the level of awareness and tourist use is not high. The underground routes with the highest cultural heritage value are also those with high tourist potential

Theory and application of explicitly correlated Gaussians

The variational method complemented with the use of explicitly correlated Gaussian basis functions is one of the most powerful approaches currently used for calculating the properties of few-body systems. Despite its conceptual simplicity, the method offers great flexibility, high accuracy, and can be used to study diverse quantum systems, ranging from small atoms and molecules to light nuclei, hadrons, quantum dots, and Efimov systems. The basic theoretical foundations are discussed, recent advances in the applications of explicitly correlated Gaussians in physics and chemistry are reviewed, and the strengths and weaknesses of the explicitly correlated Gaussians approach are compared with other few-body technique

Desorption of alkali atoms from 4He nanodroplets

The dynamics following the photoexcitation of Na and Li atoms located on the surface of helium nanodroplets has been investigated in a joint experimental and theoretical study. Photoelectron spectroscopy has revealed that excitation of the alkali atoms via the (n+1) -> ns transition leads to the desorption of these atoms. The mean kinetic energy of the desorbed atoms, as determined by ion imaging, shows a linear dependence on excitation frequency. These experimental findings are analyzed within a three-dimensional, time-dependent density functional approach for the helium droplet combined with a Bohmian dynamics description of the desorbing atom. This hybrid method reproduces well the key experimental observables. The dependence of the observables on the impurity mass is discussed by comparing the results obtained for the 6Li and 7Li isotopes. The calculations show that the desorption of the excited alkali atom is accompanied by the creation of highly non-linear density waves in the helium droplet that propagate at supersonic velocities

Molecular effects in the neutrino mass determination from beta-decay of the tritium molecule

Molecular final state energies and transition probabilities have been computed for beta-decay of the tritium molecule. The results are of sufficient accuracy to make a determination of the electron neutrino rest mass with an error not exceeding a few tenths of an electron volt. Effects of approximate models of tritium beta-decay on the neutrino mass determination are discussed. 14 refs., 3 figs., 1 tab