RESUMO
Near- and mid-IR absorption spectra of endohedral H2@C60+ have been measured using He-tagging. The samples have been prepared using a "molecular surgery" synthetic approach and were ionized and spectroscopically characterized in the gas phase. In contrast to neutral C60 and H2@C60, the corresponding He-tagged cationic species show distinct spectral differences. Shifts and line splittings in the near- and mid-IR regions indicate the influence of the caged hydrogen molecule on both the electronic ground and excited states. Possible relevance to astronomy is discussed.
RESUMO
The structure of doubly ionized benzene has been spectroscopically studied for the first time. Helium-tagged complexes were prepared at temperatures below 4 K and analyzed using infrared predissociation spectroscopy. Double ionization of benzene yields primarily high-energy dications with a six-membered-ring structure. Some of the dications undergo rearrangement to a more stable pyramidal isomer with a C5H5 base and CH at the apex. By means of isomer-selective heating by a CO2 laser, infrared predissociation spectra of both the classical and pyramidal dications were obtained.
RESUMO
The neutral molecule temperature dependence of the rate coefficient for the electron transfer reaction from H(2)O to N(2)(+) is determined using a coaxial molecular beam radio frequency ring electrode ion trap (CoMB-RET) method. The temperature of the N(2)(+) ions was maintained at 100 K, while the effusive water beam temperature was varied from 300 to 450 K. The result demonstrates the neutral molecule rotational/translational energy dependence on the rate coefficient of an ion-dipolar molecule reaction. It is found that the rate coefficient in the above temperature range follows the prediction of the simplest ion-dipole capture model. Use of different buffer gas collisional cooling in both the ion source and the RET reveals the effects of both translational and vibrational energy of the N(2)(+) ions.