Particle formation and surface processes on atmospheric aerosols: a review of applied quantum chemical calculations

Aerosols significantly influence atmospheric processes such as cloud nucleation, het- erogeneous chemistry, and heavy-metal transport in the troposphere. The chemical and physical complexity of atmospheric aerosols results in large uncertainties in their climate and health effects. In this article, we review recent advances in scientific understanding of aerosol processes achieved by the application of quantum chemical calculations. In particular, we emphasize recent work in two areas: new particle for- mation and heterogeneous processes. Details in quantum chemical methods are pro- vided, elaborating on computational models for prenucleation, secondary organic aerosol formation, and aerosol interface phenomena. Modeling of relative humidity effects, aerosol surfaces, and chemical kinetics of reaction pathways is discussed. Because of their relevance, quantum chemical calculations and field and laboratory experiments are compared. In addition to describing the atmospheric relevance of the computational models, this article also presents future challenges in quantum chemical calculations applied to aerosols

Daytime Formation of Nitrous Acid at Atmospheric Interfaces: Mechanistic Studies under Environmentally Relevant Conditions

Nitrous acid (HONO) is an atmospheric trace gas known to accumulate during nighttime and undergo rapid photodissociation during the day to form NO and highly reactive hydroxyl radicals, making accurate HONO estimations important in understanding atmospheric reactions. However, HONO is often underestimated in global atmospheric models because its sources and sinks are not well understood. Despite its photolysis, field observations have found quasi-steady-state concentrations of HONO at midday, suggesting the presence of photoproduction pathways to replenish daytime atmospheric HONO. Recent studies suggest that the presence of complex organic photosensitizers in aerosols can convert atmospheric nitrogen dioxide (NO2) into HONO and other nitrogenous gases, but the influence of environmental conditions have not been well studied. To better understand the effect of environmental photosensitizers on daytime mechanisms of HONO formation, we present here laboratory studies on the heterogeneous photolytic reduction of NO2 by humic acid films, an environmental photosensitizer and proxy for marine chromophoric compounds. The effect of relevant environmental conditions like pH and the presence of chloride ions on the formation of HONO and other nitrogenous gases is investigated. A dual FTIR system is utilized to simultaneously perform in-situ analysis of condensed-phase reactants and gas-phase products. We find that HONO is preferentially formed in the presence of chloride ions and does not have a strong pH dependence. Reactive uptake of NO2 onto the humic acid is observed, especially in the absence of chloride ions, suggesting competing pathways which suppress daytime formation of nitrogenous gases. Significantly, the presence of chloride ions also leads to a previously undiscovered daytime production pathway of nitrosyl chloride (ClNO), a precursor to HONO and a source of atomic chlorine, through photosensitization of the organic chromophore. In addition to photosensitized products, NO­2 desorbs from the surface, nitic oxide (NO) accumulates from the dissociation of photosensitive gases, and nitrous oxide (N2O) is produced thermally. Overall, this work shows that organic photosensitizers can reduce adsorbed NO2 to form HONO, ClNO, NO, and N2O while simultaneously incorporating nitrogen into the organic chromophores present in aerosols

TOI-1136 is a Young, Coplanar, Aligned Planetary System in a Pristine Resonant Chain

Convergent disk migration has long been suspected to be responsible for forming planetary systems with a chain of mean-motion resonances (MMRs). Dynamical evolution over time could disrupt the delicate resonant configuration. We present TOI-1136, a 700 ± 150 Myr old G star hosting at least six transiting planets between ∼2 and 5 R _⊕ . The orbital period ratios deviate from exact commensurability by only 10 ^−4 , smaller than the ∼10 ^−2 deviations seen in typical Kepler near-resonant systems. A transit-timing analysis measured the masses of the planets (3–8 M _⊕ ) and demonstrated that the planets in TOI-1136 are in true resonances with librating resonant angles. Based on a Rossiter–McLaughlin measurement of planet d, the star’s rotation appears to be aligned with the planetary orbital planes. The well-aligned planetary system and the lack of a detected binary companion together suggest that TOI-1136's resonant chain formed in an isolated, quiescent disk with no stellar flyby, disk warp, or significant axial asymmetry. With period ratios near 3:2, 2:1, 3:2, 7:5, and 3:2, TOI-1136 is the first known resonant chain involving a second-order MMR (7:5) between two first-order MMRs. The formation of the delicate 7:5 resonance places strong constraints on the system’s migration history. Short-scale (starting from ∼0.1 au) Type-I migration with an inner disk edge is most consistent with the formation of TOI-1136. A low disk surface density (Σ _1 au ≲ 10 ^3 g cm ^−2 ; lower than the minimum-mass solar nebula) and the resultant slower migration rate likely facilitated the formation of the 7:5 second-order MMR

TOI-2109: An Ultrahot Gas Giant on a 16 hr Orbit

We report the discovery of an ultrahot Jupiter with an extremely short orbital period of 0.67247414 0.00000028 days (∼16 hr). The 1.347 0.047 R Jup planet, initially identified by the Transiting Exoplanet Survey Satellite (TESS) mission, orbits TOI-2109 (TIC 392476080) - a T eff ∼ 6500 K F-type star with a mass of 1.447 0.077 M , a radius of 1.698 0.060 R , and a rotational velocity of v sin i ∗ }=81.9\pm 1.7 km s-1. The planetary nature of TOI-2109b was confirmed through radial-velocity measurements, which yielded a planet mass of 5.02 0.75 M Jup. Analysis of the Doppler shadow in spectroscopic transit observations indicates a well-aligned system, with a sky-projected obliquity of λ = 1. 7 1. 7. From the TESS full-orbit light curve, we measured a secondary eclipse depth of 731 46 ppm, as well as phase-curve variations from the planet's longitudinal brightness modulation and ellipsoidal distortion of the host star. Combining the TESS-band occultation measurement with a K s -band secondary eclipse depth (2012 80 ppm) derived from ground-based observations, we find that the dayside emission of TOI-2109b is consistent with a brightness temperature of 3631 69 K, making it the second hottest exoplanet hitherto discovered. By virtue of its extreme irradiation and strong planet-star gravitational interaction, TOI-2109b is an exceptionally promising target for intensive follow-up studies using current and near-future telescope facilities to probe for orbital decay, detect tidally driven atmospheric escape, and assess the impacts of H2 dissociation and recombination on the global heat transport

Reproducibility Project: Psychology

Reproducibility is a defining feature of science, but the extent to which it characterizes current research is unknown. We conducted replications of 100 experimental and correlational studies published in three psychology journals using high-powered designs and original materials when available