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The first rotationally resolved observation of the infrared (IR) spectrum of the molecular complex C3H4–HCl in gas phase is reported. New IR spectra have been recorded at high resolution by means of a slit jet. Rotational constants and vibrational frequencies have been obtained from these spectra. These data are presented and compared with high level ab initio calculations (CCSD(T)/cc-pVTZ). The results obtained in this study are compared with those on acetylene and ethene-HCl complexes. We observe a broadening of the lines interpreted as a decrease of the lifetime of the excited vibrational state with the size of the partner of complexation and also a correlation between the vibrational shift of the H–Cl stretching mode and the proton affinity of the acceptor molecule. [ABSTRACT FROM AUTHOR]

Recent experiments have investigated the dissociative ionization of NaI and CsI, each aggregated with a molecule of acetonitrile CH[sub 3]CN, using two femtosecond laser pulses. The first, the pump pulse, excites the NaI or CsI diatom to a dissociative state. The second, the probe pulse, then ionizes the sodium or cesium atom after a variable delay time, and the resulting ion is detected. In the case of NaI, the ion signal is characterized by a single maximum. For CsI, however, an oscillatory signal is observed. By performing two-dimensional wave packet propagations, we are able to reproduce this behavior, which can be explained using simple physical arguments. [ABSTRACT FROM AUTHOR]