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1. Circumgalactic Ly α emission around submillimeter-bright galaxies with different quasar contributions

   https://doi.org/10.1051/0004-6361/202346879  

   González_Lobos, Vale; Arrigoni_Battaia, Fabrizio; Chang, Seok-Jun; Gronke, Max; Kauffmann, Guinevere; Chen, Chian-Chou; Fu, Hai; Obreja, Aura; Farina, Emanuele P (November 2023, Astronomy & Astrophysics)

   We present VLT/MUSE observations targeting the extended Lyman-α(Lyα) emission of five high-redshift (z ∼ 3-4) submillimeter galaxies (SMGs) with increasing quasi-stellar object (QSO) radiation: two SMGs; two SMGs that host a QSO; and one SMG that hosts a QSO with an SMG companion (QSO+SMG). These sources are predicted to be located in dark matter halos of comparable masses (average mass ofM_DM ∼ 10^12.2 M_⊙). We quantified the luminosity and extent of the Lyαemission, together with its kinematics, and examined four Lyαpowering mechanisms: photoionization from QSOs or star formation, shocks by galactic and/or QSO outflows, gravitational cooling radiation, and Lyαphoton resonant scattering. We find a variety of Lyαluminosities and extents, with the QSO+SMG system displaying the most extended and bright nebula, followed by the SMGs hosting a QSO, and finally the undetected circumgalactic medium of SMGs. This diversity implies that gravitational cooling is unlikely to be the main powering mechanism. We show that photoionization from the QSO and QSO outflows can contribute to power the emission for average densitiesn_H > 0.5 cm⁻³. Moreover, the observed Lyαluminosities scale with the QSO’s budget of Lyαphotons modulo the dust content in each galaxy, highlighting a possible contribution from resonant scattering of QSO radiation in powering the nebulae. We find larger Lyαlinewidths (FWHM ≳ 1200 km s⁻¹) than usually reported around radio-quiet systems, pointing to large-scale outflows. A statistical survey targeting similar high-redshift massive systems with known host properties is needed to confirm our findings. 

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2. Flux-driven algebraic damping of m   =  2 diocotron mode

   https://doi.org/10.1063/5.0060022  

   Chim, Chi Yung; O'Neil, Thomas M. (September 2021, Physics of Plasmas)
3. Going beyond the borders: pyrrolo[3,2- b ]pyrroles with deep red emission

   https://doi.org/10.1039/d1sc05007a  

   Tasior, Mariusz; Kowalczyk, Paweł; Przybył, Marta; Czichy, Małgorzata; Janasik, Patryk; Bousquet, Manon H.; Łapkowski, Mieczysław; Rammo, Matt; Rebane, Aleksander; Jacquemin, Denis; et al (December 2021, Chemical Science)

   A two-step route to strongly absorbing and efficiently orange to deep red fluorescent, doubly B/N-doped, ladder-type pyrrolo[3,2- b ]pyrroles has been developed. We synthesize and study a series of derivatives of these four-coordinate boron-containing, nominally quadrupolar materials, which mostly exhibit one-photon absorption in the 500–600 nm range with the peak molar extinction coefficients reaching 150 000, and emission in the 520–670 nm range with the fluorescence quantum yields reaching 0.90. Within the family of these ultrastable dyes even small structural changes lead to significant variations of the photophysical properties, in some cases attributed to reversal of energy ordering of alternate-parity excited electronic states. Effective preservation of ground-state inversion symmetry was evidenced by very weak two-photon absorption (2PA) at excitation wavelengths corresponding to the lowest-energy, strongly one-photon allowed purely electronic transition. π-Expanded derivatives and those possessing electron-donating groups showed the most red-shifted absorption- and emission spectra, while displaying remarkably high peak 2PA cross-section ( σ 2PA ) values reaching ∼2400 GM at around 760 nm, corresponding to a two-photon allowed higher-energy excited state. At the same time, derivatives lacking π-expansion were found to have a relatively weak 2PA peak centered at ca. 800–900 nm with the maximum σ 2PA ∼50–250 GM. Our findings are augmented by theoretical calculations performed using TD-DFT method, which reproduce the main experimental trends, including the 2PA, in a nearly quantitative manner. Electrochemical studies revealed that the HOMO of the new dyes is located at ca . −5.35 eV making them relatively electron rich in spite of the presence of two B − –N + dative bonds. These dyes undergo a fully reversible first oxidation, located on the diphenylpyrrolo[3,2- b ]pyrrole core, directly to the di(radical cation) stage. 

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4. Triple Emission of 5′-( para -R-Phenylene)vinylene-2-(2′-hydroxyphenyl)benzoxazole (PVHBO). Part I: Dual Emission from the Neutral Species

   https://doi.org/10.1021/acs.jpca.1c10165  

   Meisner, Quinton J.; Hurley, Joseph J.; Guo, Peijun; Blood, Anna R.; Schaller, Richard D.; Gosztola, David J.; Wiederrecht, Gary P.; Zhu, Lei (February 2022, The Journal of Physical Chemistry A)
5. Hydrogen centers as a probe of VGa(2) defects in β -Ga2O3

   https://doi.org/10.1063/5.0138904  

   Portoff, Amanda; Stavola, Michael; Fowler, W. Beall; Pearton, Stephen J.; Glaser, Evan R. (February 2023, Applied Physics Letters)

   While a number of O-H and O-D vibrational lines have been observed for hydrogen and deuterium in β-Ga2O3, it has been commonly reported that there is no absorption with a component of the polarization E parallel to the [010], or b, axis. This experimental result has led to O-H defect structures that involve shifted configurations of a vacancy at the tetrahedrally coordinated Ga(1) site [VGa(1)] and have ruled out structures that involve a vacancy at the octahedrally coordinated Ga(2) site [VGa(2)], because these structures are predicted to show absorption for E//[010]. In this Letter, weak O-D lines at 2475 and 2493 cm−1 with a component of their polarization with E//[010] are reported for β-Ga2O3 that had been annealed in a D2 ambient. O-D defect structures involving an unshifted VGa(2) are proposed for these centers. An estimate is made that the concentration of VGa(2) in a Czochralski-grown sample is 2–3 orders of magnitude lower than that of VGa(1) from the intensities of the IR absorption lines. 

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