Laser Chemistry
Volume 18 (1998), Issue 1-2, Pages 51-62
doi:10.1155/1998/25701
Nanosecond Versus, Picosecond Molecular Multiphoton Fragmentation of Ketene
and Cyclohexane
Instituto de Química Física, CSIC, Serrano 119, Madrid 28006, Spain
Received 10 November 1997
Abstract
Multiphoton dissociation of ketene was studied at 290.5 nm after irradiation of the first
excited singlet state with two different laser pulsewidths of 4 ns and 10 ps. Analysis of the
photofragment fluorescence spectra in the two time domains sheds light on the
mechanisms that are responsible for the production of the observed CH(A2Δ), (B2Σ−)
and C2(d3Πg) photofragments. Multiphoton ionization of cyclohexane induced by a
visible laser at 581 nm and its second harmonic at 290.5 nm was measured in the above
mentioned pulse duration regimes. Study of the dependence of the total ionization signal
on pressure and laser energy helps to clarify the role played by the giant resonance of this
molecule at 84000 cm-1 in the photoionization process.