Improved production of Br atoms near zero speed by photodissociating laser aligned Br2 molecules

We theoretically investigated the improvement on the production rate of the decelerated bromine (Br) atoms near zero speed by photodissociating laser aligned Br2 precursors. Adiabatic alignment of Br2 precursors exposed to long laser pulses with duration on the order of nanoseconds was investigated by solving the time-dependent Schrödinger equation. The dynamical fragmentation of adiabatically aligned Br2 precursors was simulated and velocity distribution of the Br atoms produced was analyzed. Our study shows that the larger the degree of the precursor alignment, ⟨cos(2) θ⟩, the higher the production rate of the decelerated Br atoms near zero speed. For Br2 molecules with an initial rotational temperature of ~1 K, a ⟨cos(2) θ⟩ value of ~0.88 can result in an improvement factor of over ~20 on the production rate of the decelerated Br atoms near zero speed, requiring a laser intensity of only ~1 × 10(12) W/cm(2) for alignment.