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Keywords:

  • ab initio calculations;
  • laser chemistry;
  • nitrosyl chloride;
  • photochemistry;
  • velocity map imaging

Abstract

Ultrafast photodissociation of the 2 1A′ state of ClNO, which has an absorption spectrum peaking at 335 nm, is studied by computational and experimental methods. New potential-energy surfaces are calculated for the 1 and 2 1A′ states at the multireference configuration interaction (MRCI) level. Wavepacket dynamics simulations performed both exactly and by using the multiconfiguration time-dependent Hartree method yield essentially identical results. Transition dipole moments at a range of geometries are included in these calculations to correctly model the excitation. Vibrational and rotational state distributions of the NO product are obtained both computationally by analysing the quantum flux on the 2 1A′ surface and experimentally by use of 3D resonant multiphoton ionisation (REMPI), a variant of the velocity map imaging technique. The nascent NO is found to be only marginally vibrationally excited, with 91 % formed in v=0. The calculated NO rotational distribution peaks in the j=45–55 region, which compares favourably to experiment.