MEASUREMENTS OF THE RADIATIVE LIFETIMES OF TIO A(3)PHI,B-3-PI,C-3-DELTA,C(1)PHI,F(1)DELTA,E(3)PI) STATES

TiO molecules have been generated in X(3) Delta and a(1) Delta dark st ates within a collimated, pulsed, supersonic molecular beam. The rotat ional cooling produced in the expansion and the collision-free nature of the beam provide conditions particularly well suited to direct radi ative lifetime determinations. Analysis of fluorescence decay followin g pulsed dye-laser excitation of the TiO molecules through the gamma(A (3) Phi-X(3) Delta), gamma'((BII)-I-3-X(3) Delta), alpha(C-3 Delta-X(3 ) Delta), beta(c(1) Phi-a(1) Delta), (f(1) Delta-a(1) Delta> and epsil on(E(3)II-X(3) Delta) transitions has produced a set of precise lifeti me measurements for five electronically excited states, A(3) Phi, (BII )-I-3, C-3 Delta, c(1) Phi, f(1) Delta, the latter being previously un measured, and a rough lower limit for the E(3)II state. The following values have been found (errors quoted at 95% confidence interval): A(3 ) Phi(2) state, tau(upsilon=0) = 103.3 +/- 3.6 ns, tau(upsilon=1) = 11 2.9 +/- 1.8 ns; A(3) Phi(3) state, tau(upsilon=0) = 101.9 +/- 3.6 ns, tau(upsilon=1) = 109.2 +/- 2.8 ns; A(3) Phi(4) state, tau(upsilon=0) = 98.7 +/- 4.4 ns, tau(upsilon=1) = 105.6 +/- 3.6 ns; (BII0)-I-3 state, tau(upsilon=0) = 65.6 +/- 1.2 ns, tau(upsilon=1) = 66.5 +/- 1.0 ns, t au(upsilon=2) 63.8 +/- 1.4 ns; (BII1)-I-3 state, tau(upsilon=0) = 64.6 +/- 1.6 ns, tau(upsilon=1) = 67.6 +/- 1.2 ns, tau(upsilon=2) = 67.8 /- 1.4 ns; (BII2)-I-3 state, tau(upsilon=0) = 66.1 +/- 1.2 ns, tau(ups ilon=1) = 69.0 +/- 1.2 ns, tau(upsilon=2) = 68.1 +/- 2.0 ns; C-3 Delta state, tau(upsilon=0) = 43.3 +/- 1.0 ns, tau(upsilon=1) = 43.0 +/- 1. 2 ns; c(1) Phi state, tau(upsilon=0) = 38.3 +/- 1.6 ns, tau(upsilon=1) = 37.3 +/- 5.2 ns; f(1) Delta state, tau(upsilon=0) = 43.2 +/- 2.0 ns . For the E(3)II state, a value tau(upsilon=0) > 2000 ns is suggested. Most of these values differ from previous determinations by more than the quoted experimental uncertainty. Recommended values for the band oscillator strengths, derived from these data, are also given.