  In this work, solid targets made from boron and boron nitride (BN) materials
are ablated by a nanosecond pulsed laser at sub-atmospheric pressures of
nitrogen and helium gases. Excited species in the ablation plume from the
target are probed with spatiotemporally resolved optical emission spectroscopy
(OES). Evaluation of chemical composition in the plasma plume revealed that for
both boron-rich targets, emission from BN molecules is always observed in
nitrogen-rich environments. In addition, BN molecules also present when
ablating a boron nitride target in helium gas -- an indication that BN
molecules in the plume may originate from the solid target. Furthermore, the
ablation of BN target features emission of B2N molecules, regardless of the
pressure and surrounding gas. These results suggest that the ablation of the BN
target is more favorable for the generation of complex molecules containing
boron and nitrogen species and possibly hint that BN is also more favorable
feedstock for high-yield BN nanomaterial synthesis. Plasma parameters such as
electron temperature (peak value of 1.3 eV) and density (peak value of 2x10^18
cm^-3) were also investigated in this work in order to discuss the chemical
dynamics in the plume.
