We describe how the photon-initiated reaction technique has been used to provide dynamical information about elementary gas-phase bimolecular reactions at the product quantum state-resolved level. The primary focus is on the product angular scattering and rotational angular momentum polarization information that can be obtained from bulb experiments. We illustrate how particular insight into the reaction mechanism is provided by comparisons with the results of model calculations and with ab initio theoretical predictions obtained by others in the field. We show how the experimental measurements have helped provide a critical assessment of the ability of current theory to predict the outcome of simple chemical reactions. The bimolecular systems discussed include the reaction of O(D-1) with H-2 and the H atom reactions with H2O and N2O. Measurement of angular momentum orientation is also illustrated by reference to the photodissociation on NO2. Future developments of the photon-initiated reaction technique are also discussed.