Measurement of the isotope shift of the $2{{\rm{p}}}^{4}{}^{3}{{P}}_{2} \rightarrow 2{{\rm{p}}}^{3}3{\rm{p}}{}^{3}{{P}}_{2}$ two-photon transition of O I and a revision of the triplet energy levels of atomic oxygen

Abstract

Two-photon induced fluorescence of atomic oxygen, which is routinely used for plasma and flame diagnostics, is implemented with two counterpropagating laser beams of sufficient monochromaticity to permit Doppler-free spectroscopy. A single-mode injection-seeded pulsed Ti:sapphire laser has been frequency-doubled twice to produce narrow-band pulsed radiation at wavelengths around 225.6nm, suitable to excite the ground-state-to-P 2p 3p 3 3 two-photon resonance line of oxygen. Accurate measurement of the injection-seeding wavelength provides new data on the excitation energy of the P 3p 3 states. The experiment was done both sequentially and simultaneously on 16 O and 18 O, which makes it possible to test recent calculations of the isotope shift. Having an absolute measurement of the excitation wave-number from the ground level, which has been the case only twice in previous spectroscopic studies of OI, we can reexamine the energy levels of the subset of triplet states and present an updated set of optimised energy values.

Oxygen atom kinetics in CO2 plasmas ignited in a DC glow discharge

“…As can be seen, the high spectral resolution of the laser allows us to partially resolve the fine structure of the excited level O (3p 3 P); the contributions of the levels J=1 (88630.59 cm −1 , fluorescence transition 3p 3 P J=1 → 3s 3 S J=1 ) and J=2 (88631.15 cm −1 , transition 3p 3 P J=2 → 3s 3 S J=1 ) are easily distinguished. The J=0 (88631.30 cm −1 ) contribution is weaker and convoluted with that from J=2 one [88]. In the conditions studied in this work, these profiles are dominated by Doppler broadening (i.e.…”

Vacuum Ultraviolet Fourier-transform Spectroscopy of 16O and 18O

“…Those measurements were carried out in the near-infrared region (800-13,000 cm −1 ), mostly probing levels of high angular momentum. The accurate data from Ivanov et al (2008) and Marinov et al (2017) were included in their level analysis, in addition to the earlier accurate data by Eriksson andcoworkers (Eriksson &Isberg 1963, 1964;Eriksson 1965;Eriksson & Isberg 1968;Isberg 1968). Civiš et al performed a comprehensive reevaluation of O I level energies with 2p 3 ( 4 S)nl configuration with n up to 8.…”

“…Ivanov et al (2008) measured Doppler-free VUV O I spectra with narrowband harmonic-upconverted laser sources in the wavelength range 94-103 nm with estimated uncertainties of 0.008 cm −1 . Two-photon Doppler-free spectroscopy with a narrowband 226 nm laser source was employed by Marinov et al (2017) to reach 3p 3 P states with uncertainties estimated at 0.0019 cm −1 . In these high-resolution laser spectroscopic studies the fine structure of some excited levels could be resolved.…”

“…Currently the most accurate compilation for the ultraviolet lines of O I is that reported by Civiš et al (2018). While their measurements were performed in the near-and mid-infrared wavelength ranges, they have combined all of the accurate information from the studies mentioned above (Eriksson & Isberg 1963, 1968Isberg 1968;Lurie & Baird 1986;Brown et al 1987;Chang et al 1988;Ivanov et al 2008;Marinov et al 2017).…”

Raman mapping of photodissociation regions

“…Also listed in Table A1 are the Raman transformations 𝜆 1 → 𝜆 2 for the rest wavelengths of transitions between the ground 2s 2 2p 4 3 P term of neutral 16 O and the excited 2s 2 2p 3 3d 3 D o term. The O I data is obtained from highly accurate laser metrology (Ivanov et al 2008;Marinov et al 2017), with a precision of 0.08 cm −1 or better. The fine structure splitting between the 𝐽 𝑘 levels of the excited term (∼ 0.1 cm −1 ) is much smaller than that between the 𝐽 𝑖 levels of the ground term (∼ 100 cm −2 ), so that the 6 transitions fall into 3 well-separated groups.…”