Time-resolved diode laser infrared absorption/gain spectroscopy was used to determine relative populations of the 000 and 010 vibrational states of H2O produced in the reaction of OH with cyclohexane and cyclooctane. Both reaction systems produced vibrational population inversions in the multiple-collision regime. The experimental results demonstrate the ability to make significant variations in temporal gain profiles with minor modifications of reactant structure. A gain coefficient model was developed to calculate H2O vibrational state population ratios. The cyclohexane reaction, using a mixture of 700 m Torr of organic + 500 m Torr of acid, was found to have a population ratio 010/000 = 2.8 +/- 0.4 for times between 7.5 and 40 mu s, with a peak gain signal at 15 mu s. For the same pressure conditions, cyclooctane produced an average 010/000 = 1.1 +/- 0.2 over times from 50 to 1000 mu s. Kinetic modeling was utilized to demonstrate the role of secondary reactions in providing a continuing source of H2O out to a few hundred microseconds. Limiting-case vibrational state population models were developed to illustrate the role of reaction dynamics and collisional quenching in determining population inversions.