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Title: Laboratory Study of the Cameron Bands, the First Negative Bands, and Fourth Positive Bands in the Middle Ultraviolet 180–280 nm by Electron Impact upon CO
We have analyzed medium-resolution (FWHM = 1.2 nm) Middle UltraViolet (MUV; 180–280 nm) laboratory emission spectra of CO excited by electron impact at 15, 20, 40, 50, and 100 eV under single-scattering conditions at 300 K. The MUV emission spectra at 100 eV contain the Cameron Bands (CB) CO(a 3Π → X 1Σ+), the Fourth Positive Group (4PG) CO(A 1Π → X 1Σ+), and the First Negative Group (1NG) CO+(B 2Σ+ → X 2Σ) from direct excitation and cascading-induced emission of an optically-thin CO gas. We have determined vibrational intensities and emission cross sections for these systems, which are important for modeling UV observations of the atmospheres of Mars and Venus. We have also measured the CB ‘glow’ profile about the electron beam of the long-lived CO (a 3Π) state and determined its average metastable lifetime of approximately 3 ± 1 ms. Optically-allowed cascading from a host of triplet states has been found to be the dominant excitation process contributing to the CB emission cross section at 15 eV, most strongly by the d 3Δ and a' 3Σ+ electronic states. We normalized the CB emission cross section at 15 eV electron impact energy by Multi-Linear Regression (MLR) analysis to the more » blended 15 eV MUV spectrum over the spectral range of 180–280 nm, based on the 4PG emission cross section at 15 eV that we have previously measured (Ajello et al., 2019). We find the Cameron band total emission cross section at 15 eV to be (7.65 ± 2.68) × 10−17 cm2. « less
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Journal of Geological Research
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National Science Foundation
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Fig. 3(b) shows the tunneling probability T according to the Kane two-band model in the three materials, In0.53Ga0.47As, GaAs, and GaN, following our observation of a similar electroluminescence mechanism in GaN/AlN RTDs (due to strong polarization field of wurtzite structures) [8]. The expression is Tinter = (2/9)∙exp[(-2 ∙Ug 2 ∙me)/(2h∙P∙E)], where Ug is the bandgap energy, P is the valence-to-conduction-band momentum matrix element, and E is the electric field. Values for the highest calculated internal E fields for the InGaAs and GaN are also shown, indicating that Tinter in those structures approaches values of ~10-5. As shown, a GaAs RTD would require an internal field of ~6×105 V/cm, which is rarely realized in standard GaAs RTDs, perhaps explaining why there have been few if any reports of room-temperature electroluminescence in the GaAs devices. [1] E.R. Brown,et al., Appl. Phys. Lett., vol. 58, 2291, 1991. [5] S. Sze, Physics of Semiconductor Devices, 2nd Ed. 12.2.1 (Wiley, 1981). [2] M. Feiginov et al., Appl. Phys. Lett., 99, 233506, 2011. [6] L. Coldren, Diode Lasers and Photonic Integrated Circuits, (Wiley, 1995). [3] Y. Nishida et al., Nature Sci. Reports, 9, 18125, 2019. [7] E.O. Kane, J. of Appl. Phy 32, 83 (1961). [4] P. Fakhimi, et al., 2019 DRC Conference Digest. [8] T. Growden, et al., Nature Light: Science & Applications 7, 17150 (2018). [5] S. Sze, Physics of Semiconductor Devices, 2nd Ed. 12.2.1 (Wiley, 1981). [6] L. Coldren, Diode Lasers and Photonic Integrated Circuits, (Wiley, 1995). [7] E.O. Kane, J. of Appl. Phy 32, 83 (1961). [8] T. Growden, et al., Nature Light: Science & Applications 7, 17150 (2018).« less
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