LIF SPECTRA OF N-PROPOXY AND I-PROPOXY RADICALS AND KINETICS OF THEIRREACTIONS WITH O-2 AND NO2

Fluorescence excitation spectra of CH3CH2CH2O (n-propoxy) and (CH3)(2) CHO (i-propoxy) radicals were obtained using a combined laser photolys is/laser-induced fluorescence (LIF) technique and the kinetics of reac tions 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 r adicals were produced by excimer laser photolysis of the appropriate p ropyl nitrites at lambda=351 nm. The spectra of the ((A) over bar-->(X ) over bar) transitions show progressions of the GO-stretching vibrati on 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. F luorescence 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-prop oxy) show progressions of the GO-stretching vibration in the electroni c 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-propo xy 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 ra nge 218-313 K. The rate coefficients for the reactions of NO2 with n-p ropoxy 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).