Energy transfer and energy pooling from Ba[6s5d( 3D 1,2,3)) generated following pulsed dye-laser excitation at λ = 553.5 nm [formula omitted] and monitored by time-resolved atomic emission from Ba[6s5d( 1D 2)], Ba[6s6p( 3P 1)] and Ba[6s6p( 1P 1)] part I

Abstract

We present a kinetic study of Ba[6s5d( 3D J )], 1.151 eV above the 6s 2( 1S 0) ground state ( J=1, 1.120, J=2, 1.143, J=3, 1.190 eV). This was generated indirectly following the initial pulsed dye-laser excitation of atomic barium vapour at elevated temperature at λ = 553.5 nm { Ba(6 s6 p( 1 P 1)] ← Ba[6 s 2( 1 S 0)]} in the presence of helium buffer gas in a slow flow syst kinetically equivalent to a static system. The 3D J state was subsequently populated by various emission and collisional process from Ba( 1P 1), including cascading via Ba[6s6p( 3P J )] which is generated in this system. Direct monitoring via emission in the time-domain from Ba[6 s5 d( 3 D 1)] → Ba[6 s 2( 1 S 0)] + hv ( λ = 1106.9 nm) using an interference filter and a new long wavelength response tube (S21) operating in this wavelength region did not prove sufficiently sensitive. Time-resolved emission measurements in the long-time regime (ca. 3 ms) at λ = 791.1 nm { Ba[6 s6 p( 3 P 1)] → Ba[6 s 2( 1 S 0)]} and λ = 877.4 nm { Ba[6 s5 d( 1 D 2)] → Ba[6 s 2( 1 S 0)]} were made following collisional excitation of Ba( 3D J ) to the 3P J and 1D 2 state by He and Ba and, in turn, used to monitor the decay of the 3D J state itself. Further, the long-time emission (ca. 1.5 ms) at λ = 553.5 nm { Ba[6 s6 p( 1 P 1)] → Ba[6 s 2( 1 S 0)]} (τ c = 8.37 ± 0.38 ns) resulting from excitation at this wavelength was also employed to monitor Ba( 3D J ) following energy pooling to this state accompanying the Ba( 3 D J) + Ba( 3 D J) self-annihilation. The detailed mechanism for this system was considered quantitatively in terms of the optical and collisional processes for populating the emitting states employing both the form of time profiles and integrated atomic emission intensities. The results are shown to be quantitatively in accord with the proposed mechanisms for population and excitation and indicate that these time-resolved emission measurements from states resulting from energy transfer and energy pooling act as spectroscopic markers for Ba( 3D J ).