Two-photon cross-section calculations for krypton in the 190–220  nm range

Abstract

This paper presents multi-path, two-photon excitation cross-section calculations for krypton, using first-order perturbation theory. For evaluation of the two-photon-transition matrix element, this paper formulates the two-photon cross-section calculation as a matrix mechanics problem. From a finite basis of states, consisting of 4 p , 5 s , 6 s , 7 s , 5 p , 6 p , 4 d , 5 d , and 6 d orbitals, electric dipole matrix elements are constructed, and a Green’s function is expressed as a truncated, spectral expansion of solutions, satisfying the Schrödinger equation. Electric dipole matrix elements are evaluated via tabulated oscillator strengths, and where those are unavailable, quantum-defect theory is used. The relative magnitudes of two-photon cross-sections for eight krypton lines in the 190–220 nm range are compared to experimental excitation spectra with good agreement. This work provides fundamental physical understanding of the Kr atom, which adds to experimental observations of relative fluorescence intensity. This is valuable when comparing excitation schemes in different environments for krypton fluorescence experiments. We conclude that two-photon excitation at 212.556 nm is optimal for single-laser, krypton tagging velocimetry or krypton planar laser-induced fluorescence.

Picosecond two-photon absorption laser-induced fluorescence (ps-TALIF) in krypton: The role of photoionization on the density depletion of the fluorescing state Kr 5p′[3/2]2

“…Therefore, these would contribute to the formation of the long-lasting part of the region A2586 through spontaneous emissions [39][40][41]51]. Second, the formation of A2586 in Fig.…”

Evaluation of LIF thermometry technique using Krypton as a tracer: Impact of laser lineshape and collisional bandwidth

“…Recently Zelenak and Narayanaswamy [3] proposed a thermometry approach based on the twophoton LIF (TPLIF) of krypton (Kr) seeded upstream into the reacting flow. Krypton has been used as a tracer species in several applications; using X-ray fluorescence for the probe perturbation analysis [8], for thermometry [9], and using TPLIF of krypton to measure the mixture fraction in flames [10] or for high-speed flow diagnostics [11,12]. The thermometry technique in Ref [3] took advantage of the spectral line broadening with temperature.…”