Electronic transition spectrum of IrP in the spectral region between 390 and 471 nm has been recorded and analyzed using laser vaporization/reaction free jet expansion and laser induced fluorescence spectroscopy. Reacting laser-ablated iridium atoms with 1% PH3 seeded in argon produced the IrP molecule. Five electronic transition systems were identified and rotationally resolved transition lines of both the (IrP)-Ir-191 and (IrP)-Ir-193 isotopes were analyzed. Least squares fit of the rotational lines yielded molecular constants for the upper and lower states. (C) 2010 Elsevier B. V. All rights reserved.