Im. Hedgecock et al., 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, Astronomy and astrophysics, 304(2), 1995, pp. 667-677
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.