A Pulsed Source for Kr(5s[3/2]₁) Resonance State Atoms Using Two-Photon-Driven Amplified Spontaneous Emission:  Measurement of Quenching Rate Constants

Abstract

Krypton resonance state atoms, Kr(5s[3/2]1), were generated in a static cell by two-photon laser excitation of the Kr(5p[5/2]2) state with amplified spontaneous emission (ASE) at 877.7 and 810.4 nm in a few Torr of Kr gas. The 877.7 nm transition, which terminates on the resonance state, constitutes ≥90% of the ASE intensity. The vacuum ultraviolet emission at 123.6 nm was used to monitor the Kr(5s[3/2]1) concentration, which decayed with an effective lifetime of 2 μs in the absence of added reagents. Total quenching rate constants at 300 K for the resonance state atoms were measured for 30 molecules by observing the decay rates of the Kr(5s[3/2]1) atoms as a function of added reagent gas. The rate constants (cm3 molecule-1 s-1) range from 1.4 × 10-11 for N2 and 0.60 × 10-11 for CF4 to (80−90) × 10-11 for hydrocarbons. Rate constants for most polyatomic molecules exceed 30 × 10-11 cm3 molecule-1 s-1. Comparison to the quenching rate constants of the Kr(5s[3/2]2) metastable atoms shows that the rate constants of the resonance states are ∼35% larger for reagents with quenching cross sections larger than 20 Å2. For a set of 11 reagents, comparison also is made with the rate constants for the (6s) and (6s‘) resonance states and the (6p) states of Xe; the latter have nearly the same energy as the Kr(5s) resonance state.

Selective production and kinetic analysis of thermally equilibrated N2(B3Πg, v = 0) and N2(W3Δu, v = 0)

“…The rate constants obtained above are in fair agreement with the results obtained by other investigators. 4,33,34 Both Xe(6s[3/2] 1 ) and Xe(6s[3/2] 2 ) can be detected by laserinduced fluorescence. The LIF signal for Xe(6s[3/2] 1 ) decayed exponentially, but the decay was faster than that of the emission at 147.0 nm, as shown in Fig.…”

Generation and Kinetic Studies of Xe(5d[3/2]1) Resonance State Atoms

“…Equation 2 gives β 0 ∼ 1 × 10 6 s -1 for R ∼ 3 mm, τ 0 = 1.4 ns 9 , and λ = 119.2 nm. Considering the results obtained for the decay of Xe(6s[3/2] 1 ) and Kr(5s[3/2] 1 ) resonance emissions intensities, , we expect that P Xe ∼1−10 Torr is the pressure range for which the decay rate of the 5d[3/2] 1 →5p 6 1 S 0 imprisoned radiation is a constant as given by eq 2. The second term in eq 1 is the decay rate due to radiative transitions to the 6p[1/2] 1 , 6p[5/2] 2 , 6p[3/2] 1 , and 6p[3/2] 2 states.…”

“…The experimental setup was described in refs and , and we will present only a summary. The output from a Lambda Physik dye laser (LPD 3002) pumped by an XeCl laser (Questek 2840) was doubled by a BBO-II crystal to provide tunable ultraviolet laser pulses.…”

“…Two-photon excitation of Xe and Kr atoms with concomitant amplified spontaneous emission (ASE) has been shown to be a simple and convenient method for time-resolved generation of their resonance-state , atoms in an environment suitable for kinetic studies. This method was used to generate the Xe(6s[3/2] 1 ), Xe(6s‘[1/2] 1 ), and Kr(5s[3/2] 1 ) resonance-state atoms and the quenching rate constants of those atoms were measured for a wide range of molecules. , In the present paper we report an extension of this method for the generation of Xe(5d[3/2] 1 ) resonance-state atoms using two-photon excitation of the Xe(4f[3/2] 2 ) state. The energy levels of Xe are shown in Figure for convenience of presentation.…”