images and the corresponding translational energy distributions obtained after two-color irradiation of a pure ammonia cluster beam at (a) low and (b) high intensities of the pump (excitation) laser. See text for details.
Zero pump-probe time-of-flight mass spectra obtained at different pump laser intensities and the same expansion conditions. In the lowest pump laser intensity spectrum, the parent cluster distribution is apparent up to n = 12, while at the highest pump laser intensity spectrum (top panel), the parent cluster distribution is overcome by the monomer.
Difference between the 40 ns and zero delay pump-and-probe time-of-flight mass spectra obtained at the photolysis wavelength of 199 nm. The difference spectrum is dominated by the NH3 contribution. The insets show the low mass (up) and high mass (down) regions, where the hydrogen atom and the NH4(NH3) m cluster products up to m = 6 can be observed, respectively.
VMI raw image corresponding to NH4(NH3)2 products formed in the photodissociation of PyH·(NH3)3 at a photolysis wavelength of 214 nm. The double headed arrow denotes the polarization direction of both pump and probe laser pulses.
Translational energy distributions obtained by integration of the Abel inverted images corresponding to the NH4(NH3)2 fragment taken at the different photolysis wavelengths employed in the present study. The distributions have been vertically shifted for a clear comparison.
Center-of-mass (CM) translational energy distributions obtained by integration of the Abel inverted images corresponding to the NH4(NH3) m for m = 2, 3, 4 fragments at a fixed photolysis wavelength of 214 nm. The distributions have been vertically shifted for a clear comparison.
Center-of-mass (CM) translational energy distributions of the NH4(NH3)2 clusters as a function of the available energy fraction channeled into translational energy of the products. The black vertical line corresponds to the maximum fraction of available energy, and correlates with species with zero internal energy. The observed structure has been assigned to the vibrational activity of the pyrrolyl radical. As a visual guide, the combs corresponding to generic vibrational quantum states of 3000 cm−1 (ν a ) and 1500 cm−1 (ν b ) modes of the pyrrolyl co-fragment moiety have been included (top of each panel). The tail in the translational energy distribution extending towards values larger than one is related to internal energy of the ammonia chains. The vertical red lines correspond to the available energy if a quantum of the intermolecular bending mode of 452 cm−1 is included (see text for details).
Article metrics loading...
Full text loading...