Fermi resonance in Ne, Ar and Kr-matrix infrared spectra of 5-bromouracil

Low-temperature matrix isolation Fourier-transform infrared spectroscopy and quantum-chemical calcula-tions with DFT/B3LYP and MP2 methods were used for investigation of isolated 5-bromouracil (BrU) mole-cules. Only one tautomeric form of BrU was dominated in the low-temperature Ne, Ar, and Kr matrices. It was revealed that population of minor hydroxy-tautomers did not exceed 0.2%. Appearance of additional absorption bands in the region of stretching vibrations CO (about 1710 cm⁻¹) as well as of deformation ones (1297, 1093, 901 cm⁻¹) was explained by Fermi resonance. In Ne matrices the peak intensities of absorption bands assigned to the out-of-plane vibrations of the ring and exocyclic atoms were decreased sharply. For the first time, least square method with the using of polynomial was proposed for the corrective scaling of calculated frequencies of vibrations. It is shown that the correction of calculated frequencies with the polynomial of degree two permits to decrease the root-mean-square discrepancy between the calculated and experimental ones to 4–5 cm⁻¹ in the re-gion of 1500–500 cm⁻¹. The same polynomial may be applied for the correction of spectra of molecules with a similar structure

FACTS AND IDEAS IN MODERN COSMOLOGY

A review of the principles of observational testing of cosmological theories is given with a special emphasis on the distinction between observational facts and theoretical hypotheses. A classification of modern cosmological theories and possible observational tests for these theories is presented. The main rival cosmological models are analyzed from the point of view of observational testing of their initial hypothesis. A comparison of modern observational data with theoretical predictions is presented. In particular we discuss in detail the validity of the two basic assumptions of modern cosmology that are the Cosmological Principle and the Expanding Space Paradigm. It is found that classical paradigms need to be reanalyzed and that it is necessary to develop crucial cosmological tests to discriminate alternative theories.Comment: 84 pages, latex, figures are available to F.S.L ([email protected]). Accepted for publication in Vistas In astronomy, Vol.38, Part.4, 199