(CH3)3COOH (tert-butyl hydroperoxide): OH reaction rate coefficients between 206 and 375 K and the OH photolysis quantum yield at 248 nm

Rate coefficients, k, for the gas-phase reaction of the OH radical with (CH3)3COOH (tert-butyl hydroperoxide) were measured as a function of temperature (206–375 K) and pressure (25–200 Torr (He, N2)). Rate coefficients were measured under pseudo-first-order conditions using pulsed laser photolysis to produce OH and laser induced fluorescence (PLP–LIF) to measure the OH temporal profile. Two independent methods were used to determine the gas-phase infrared cross sections of (CH3)3COOH, absolute pressure and chemical titration, that were used to determine the (CH3)3COOH concentration in the LIF reactor. The temperature dependence of the rate coefficients is described, within the measurement precision, by the Arrhenius expression k1(T) = (7.0 ± 1.0) × 10−13 exp[(485 ± 20)/T] cm3 molecule−1 s−1 where k1(296 K) was measured to be (3.58 ± 0.54) × 10−12 cm3 molecule−1 s−1. The uncertainties are 2σ (95% confidence level) and include estimated systematic errors. UV absorption cross sections of (CH3)3COOH were determined at 185, 214, 228, and 254 nm and over the wavelength range 210–300 nm. The OH quantum yield following the 248 nm pulsed laser photolysis of (CH3)3COOH was measured relative to the OH quantum yields of H2O2 and HNO3 using PLP–LIF and found to be near unity.