The Coriolis Interaction between the v2 = 1 and v3 = 2 States of Nitrosyl Bromide: Anomalous Quadrupole Patterns and Interstate Transitions in the Millimeter-Wave Spectrum.
The millimeter-wave rotational spectra of 79BrNO and 81BrNO in the v2 = 1 and v3 = 2 vibrational states have been reinvestigated. Measurements of the rotational spectrum in the region of maximum c-type Coriolis interaction between the two states allowed the previous analysis to be extended to account for some uncommon effects. For the most perturbed transitions the nuclear quadrupole hyperfine structure arises from coupling of not only the bromine nucleus, but also the nitrogen nucleus with the rotational angular momentum. These effects were satisfactorily fitted with a Hamiltonian describing Coriolis coupling in a molecule with two quadrupolar nuclei. The successful analysis of pure rotational transitions then allowed accurate prediction of rovibrational transitions, six of which were measured for 79BrNO and four for 81BrNO. Copyright 1998 Academic Press.
On the refinement of the anharmonic force field of BrNO
Abstract The geometry and the anharmonic force field of BrNO have been investigated using multireference configuration interaction (MRCI) theory and, for comparison, multireference perturbation theory to second and third order (CASPT2, CASPT3) to include the dynamic correlation energy of valence electrons. The importance for the equilibrium geometry of the correlation energy terms for inner electrons, 3s, 3p, 3d of Br, has been verified using a new second order algorithm based on determinants and on the Epstein-Nesbet partition of the Hamiltonian matrix. For BrNO, compared to triatomic systems with simpler electronic shells structure, the accuracy of the MRCI treatment, restricted to the valence orbitals and electrons, is somewhat decreased with main effects on the computed equilibrium geometry. The MRCI force field and geometry have been refined empirically by least squares adjustments of the force constants against all available experimental spectroscopic parameters. Additional constraints had to be enforced to the force fields obtained with the other methods, which have been refined fixing the molecular geometry and the quartic anharmonic terms. All the refined force fields are very similar up to cubic terms and reproduce all spectral data and parameters to a good accuracy. The main differences have been found in the anharmonic quartic interactions, which, we conclude, are correctly described only by MRCI.
A New Vacuum Pressure Infiltration CFRP Method and Preparation Experimental Study of Composite
In order to prepare a carbon-fiber-reinforced polymer composite (CFRP) with ideal microstructure and properties, a new vacuum pressure infiltration CFRP method is proposed based on an analysis of existing CFRP preparation process methods. Research on composite material preparation systems was carried out by using this new method principle. The system mainly includes a fiber pre-forming module, a vacuum heating infiltration module, a hot-press curing molding module, and a data acquisition control module. Under the conditions of natural curing at 0 MPa + 6 h + 25 °C, vacuum heating curing at –0.05 MPa + 30 min + 80 °C, and hot-press curing at 0.7 MPa + 5 min + 50 °C, a two-dimensional (2D) CFRP with excellent microstructure and properties was successfully prepared. Observing the microstructure of the prepared composite material, it can be found that the inside of the composite material was sufficiently and uniformly infiltrated, and common preparation defects such as holes and delamination were effectively controlled. Through the performance test, the bending strength of the material reached 790 MPa.