Fragmentation and Recombination of Molecules during Laser Vaporization of Cryogenic Films

Laser vaporization of cryogenically condensed films of ICl and Cl2 is studied by investigating the beams of neutral atoms and molecules formed with high translational kinetic energies. The fragments resulting from the vaporization process of these molecules are examined and compared to the fragmentation patterns of molecules studied previously, XeF2 and NO. It is found that ICl shows a large amount of fragmentation and recombination during vaporization, which forms Cl2 and I2. This is also true for XeF2 and may be true for Cl2, but does not occur for NO. The degree of recombination is affected by the thickness of the cryogenic film being ablated and depends on the bond energy of the molecule with respect to the photon energy.