Chemiluminescence spectra of ScO and YO: Observation and analysis of the A′ 2Δ–X 2Σ+ band system

Abstract

A new band system between 6200 and 7500 Å has been observed in the ’’single collision’’ beam–gas chemiluminescent spectrum resulting from the reactions of Sc and Y atoms with O2. A strong, well-developed system is observed in the YO spectrum resulting from the Y–O2 reaction. A vibrational analysis of two distinct subsystems, each consisting of double-headed bands (ΔΛ?1), yields Te=14 531.2 cm −1, ωe′=794.0 cm−1, ωexe′=3.23 cm−1, ωe″=861.9 cm−1, ωexe″=2.95 cm−1 for the lower component, and Te=14 870.4 cm−1, ωe′=794.9 cm−1, ωe′=3.3 cm−1, ωe″=862.1 cm−1, ωexe″=3.025 cm−1 for the upper component. Semiempirical calculations predict Te=15 330.4 cm−1 for the A′ 2Δr state of YO. Perturbation calculations predict that mixing of the A 2Π state with the A′ 2Δ state of YO may be as large as 3.5%. On the basis of these calculations, the new band system is attributed to the A′ 2Δ–X 2Σ+ transition of YO. The new band system in the Sc+O2 spectrum is weaker and not as well resolved as the YO system. However, analysis of the system, by analogy with that of YO, yields T0=14 965.9 cm−1, ΔG′1/2 =834.0 cm−1 for the ScO A′ 2Δ3/2 state, and T0=15 072.0 cm−1, ΔG′1/2=837.0 cm−1 for the ScO A′ 2Δ5/2 state.

Photoluminescence of as an indication of crystal structure and particle size in nanoparticles synthesized by flame spray pyrolysis

“…The spectra are similar throughout the flame with the double headed, red-degraded bands typical of a thermal emission sequence with peaks in the spectra at 598 and 614 nm. These features are consistent with the A 2 1/2,3/2 → X 2 + transitions in YO that have been reported by Chalek and Gole (1976) and Wijchers, Dijkerman, Zeegers, and Alkemade (1980). We do not observe any additional spectral lines in the region between 612 and 630 nm that could be associated with Eu and we conclude that EuO or associated species are not prevalent or detectable in the gas phase, although the low concentration of Eu precursor makes it relatively difficult to detect the presence of gas phase EuO.…”

Effects of Processing Parameters on the Laser Deposition of High Temperature Superconducting Thin Films

“…2 correspond to Y*, while most of the remaining features are due to YO*. The Y* emissions are from the 2Dl/2 and 2D3/2states to the 2D3/2ground electronic state, while the YO* emission riSfrom the A 2133_.1/2levels to the 2T_,+ ground state [11,12]. Ali YO* features are due to v,= v" transitions, with the 0-0 transition being the most intense, 1-1 less intense, etc.…”

“…The result is shown in simplified form below: In addition, we have demonstrated [10] an excellent fit of equation 2) to the experimental data over the entire experimental pressure range (10-3 -0.4 torr), for a temperature ,=2000K(see below), in this calculation, we assumed formation rates constants Re1= Re2_ 1 x 1020molec/cm3-sec, resulting from the ablation of 10 ng of material during a 100 nsec surface thermal transient, into a volume of ,=10cm3. Rate constants kr2 and kq2are known from the literature [12,13] to be 2 x 10.9 cm3/molecsec. The unknown constants krt and kql were allowed to vary to produce the best fit to the experimental data; best-fit values were kt1 = 3 x 107 soc"1 (this reaction is assumed to be pseudo-first-order, with the transition effected primarily by electrons present in the laser generated plasma) and kql = 3 x i0 -9 cm3/molec-sec.…”

Rotational State Microwave Mixing for Laser Cooling of Complex Diatomic Molecules

“…Decays via magnetic dipole transitions are typically suppressed by a factor of α 2 ≈ 5 × 10 −5 compared to electric dipole transitions (α is the fine structure constant), though recent measurements in the hydroxyl radical indicate that they can be a factor of 10 faster than expected [34]. For some molecules, maintaining optical cycling can be more complex due to decays through intermediate electronic states, present in, for example, YO [35] and BaF [36]. Such decays are normally suppressed by the relatively long transition wavelengths.…”

“…The A 02 Δ 3=2 state has a radiative lifetime of ∼1 μs [35] and will rapidly decay back to the X 2 Σ state. Since the full cycle starting from and returning to the ground state is a three-photon process, parity selection rules allow decays only to even rotational states [ Fig.…”