LIF spectra of n-propoxy and i-propoxy radicals and kinetics of their reactions with O2 and NO2

Fluorescence excitation spectra of CH3CH2CH2O (n-propoxy) and (CH3)(2)CHO (i-propoxy) radicals were obtained using a combined laser photolysis/laser-induced fluorescence (LIF) technique and the kinetics of reactions of these radicals with (1) O-2 as a function of temperature and with (2) NO2 as a function of pressure have been determined. Propoxy radicals were produced by excimer laser photolysis of the appropriate propyl nitrites at lambda=351 nm. The spectra of the ((A) over bar-->(X) over bar) transitions show progressions of the GO-stretching vibration in the electronically excited states with spacings of the bands of (560+/-10) cm(-1) for i-propoxy and (580+/-10) cm(-1) for n-propoxy. Fluorescence spectra taken after excitation in the (4,0) band at lambda=340.1 nm (i-propoxy) and in the (I,O) band at lambda=342.4 nm (n-propoxy) show progressions of the GO-stretching vibration in the electronic ground state of (900+/-60) cm(-1) for i-propoxy and (1000+/-50)cm(-1) for n-propoxy. The Arrhenius expressions for the ractions of n-propoxy and i-propoxy with O? have been determined to be k(1)(n)=(1.4+/-0.6)x10(-14) exp (-(0.9+/-0.5) kJ mol(-1)lRT) cm(3) s(-1) and k(1)(i)=(1.0+/-0.3)x10(-14) exp (-(1.8+/-0.4)kJ mol(-1)/RT) cm(3) s(-1) in the range 218-313 K. The rate coefficients for the reactions of NO2 with n-propoxy and i-propoxy at T=296 K were found to be independent of total pressure with k(2)(n)=(3.6+/-0.4)x10(-11)cm(3) s(-1) (6.7-53 mbar) and k(2)(i)=(3.3+/-0.3)x10(-11) cm(3) s(-1) (6.7-106 mbar).