The results of a 355 nm photolysis study of Cl2 yield measurement of the nuclear hyperfine structure intervals in the 3s 23p5 2P3/2 → 3s23p 4(1D)4s 2D5/2 transition in the Cl35 and Cl37 atoms using a variation of the technique known as Velocity Aligned Doppler Spectroscopy. The power of the VADS technique is in the ability to extract detailed kinetic energy distributions of fragments generated during a photolysis event. High resolution frequency dependent scans exhibit structure due to the hyperfine structure of both the excited and ground states. The magnetic dipole and electric dipole quadrupole coupling constants are found and compared to previously reported constants for Cl35. The coupling constants for Cl37 are reported and compared to predicted values In addition to the results presented for Cl2 photolysis, another variation on Velocity Aligned Doppler Spectroscopy produces the results of a photolysis study of H2 and D2 in which the pulse of the photolysis laser is in the femtosecond regime are presented. A delay study between the photolysis and probe lasers displays interesting structure. The peaks in the delay study correspond not only to highly energized H atoms that one might expect if many photons were being deposited into H2 to make H+ + H + e- photoproducts, but also slow moving H atoms which seem to have no discernible kinetic energy imparted to the fragments during the photolysis event. In the case of D2, a delay study between the photolysis and probe lasers reveals structure that is highly dependent on the polarization of the photolysis laser. Concepts such as bond softening, bond hardening, and zero photon dissociation are introduced to explain the fragment energetics observed because of these high-field, short pulse events
