ESTUDIO DE COMPLEJOS INTERMOLECULARES EN FASE GASEOSA A PARTIR DE ESPECTROS ROTACIONALES DE MICROONDAS CON INYECCIÓN PULSADA

Abstract:

51 v Conventional microwave spectroscopy does not provide a proper description of intermolecular complexes since it can not produce a representative amount of such systems. The use of a pulsed nozzle overcomes this limitation because it generates a supersonic beam of gas rich in molecular complexes that can be isolated and detected. This allows it to obtain high-quality microwave spectra. Spectroscopic constants derived from these spectra generate an accurate description of the symmetry, geometry, and intermolecular bond stiffness of such complexes. In this work, the spectroscopic constants of the gas-phase dimers NH3–HX (X= Cl, Br, I) were analyzed. For NH–HC, the rotational constants, A, B and C were found to be 188.76, 4.24 and 4.24 GHz, respectively. These values indicate that the system is a symmetric rotor with C3v symmetry. The nuclear quadrupole constant, χ (35Cl), and the intermolecular stretching constant, kσ, were-47.61 MHz, and 17.6 Nm-1, respectively. These values are close to those of a hydrogen-bonded model. It is concluded that, in the gas phase, the NH–HC dimer behaves as a weakly bound complex. The NH–HB and NH–HI dimers gave similar results.

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