From optical spectra to phase diagrams—the binary mixture N2–CO

Vetter, Martin; Jodl, H. J.; Brodyanski, A.

doi:10.1063/1.2747091

Cited by 15 publications

(6 citation statements)

References 13 publications

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“…The large peak-to-peak amplitude as well as the relative and absolute longitudes of peak absorption of these species agree with previous work performed on a smaller SpeX data set in Grundy et al (2010). Both ices have similar, non-negligible sublimation pressures (Fray and Schmitt, 2009) and are fully miscible in one another (Vetter et al, 2007). However, note that the distributions are not completely in-phase, even when accounting for the uncertainty.…”

Section: Resultssupporting

confidence: 89%

On the surface composition of Triton’s southern latitudes

Holler

Young

Grundy

et al. 2016

Icarus

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We present the results of an investigation to determine the longitudinal (zonal) distributions and temporal evolution of ices on the surface of Triton. Between 2002 and 2014, we obtained 63 nights of near-infrared (0.67-2.55 µm) spectra using the SpeX instrument at NASA's Infrared Telescope Facility (IRTF). Triton has spectral features in this wavelength region from N 2 , CO, CH 4 , CO 2 , and H 2 O. Absorption features of ethane (C 2 H 6 ) and 13 CO are coincident at 2.405 µm, a feature that we detect in our spectra. We calculated the integrated band area (or fractional band depth in the case of H 2 O) in each nightly average spectrum, constructed longitudinal distributions, and quantified temporal evolution for each of the chosen absorption bands. The volatile ices (N 2 , CO, CH 4 ) show significant variability over one Triton rotation and have well-constrained longitudes of peak absorption. The non-volatile ices (CO 2 , H 2 O) show poorly-constrained peak longitudes and little variability. The longitudinal distribution of the 2.405 µm band shows little variability over one Triton rotation and is 97±44• and 92±44• out of phase with the 1.58 µm and 2.35 µm CO bands, respectively. This evidence indicates that the 2.405 µm band is due to absorption from non-volatile ethane. CH 4 absorption increased over the period of the observations while absorption from all other ices showed no statistically signifcant change. We conclude from these results that the southern latitudes of Triton are currently dominated by non-volatile ices and as the sub-solar latitude migrates northwards, a larger quantity of volatile ice is coming into view.

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Section: Resultssupporting

confidence: 89%

On the surface composition of Triton’s southern latitudes

Holler

Young

Grundy

et al. 2016

Icarus

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“…In addition, another IR frequency at 2336 cm −1 increased progressively, which may correlate with the vibration of the formed −C−O−O−C based on previous reports. 40 The above results clearly illustrate that the adsorption of molecular oxygen is located on the keto-amine structure, which is further supported by theoretical calculations. As shown in Table S3, endoperoxide species possess the lowest Gibbs free energies when O 2 is bounded to C�C in the keto-amine (Figure 5b) for both DHAA-Tp COF (0.08 eV) and TCNAQ-Tp COF (0.36 eV).…”

Section: Mechanism Studysupporting

confidence: 73%

Regulating the Tautomerization in Covalent Organic Frameworks for Efficient Sacrificial Agent-Free Photocatalytic H₂O₂ Production

Yang,

Gao,

et al. 2024

Macromolecules

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The efficiency of photocatalytic production of H 2 O 2 is constrained by the low selectivity toward oxygen reduction, and the active sites are still under debate. Herein, analogous covalent organic framework photocatalysts were synthesized from triformylphloroglucinol (Tp) and predesigned diamines, in which a molecular engineering strategy was employed to manipulate the energy barrier for the targeted proton transfers. The tautomerization of enol-imine to keto-enamine introduced abundant alkene bonds (C�C), which serve as the primary adsorption sites and have a lower energy barrier for the reduction of the O 2 reduction. DHAA-Tp COF displayed a remarkable photocatalytic H 2 O 2 production rate of 219.5 μmol h −1 g −1 without any sacrificial reagent, which stands out among the structure-related materials. A switch from a concerted one-step 2e − to a two-step single e − process in O 2 reduction was observed in TCNAQ-Tp COF, which is presumably ascribed to the suppressed tautomerization mediated by the strong electron-withdrawing cyano groups. The results demonstrate a novel concept for the photocatalytic production of H 2 O 2 using an efficient, stable, and recyclable metal-free photocatalytic system.

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“…6, has considerable scatter, but shows greater N 2 absorption on the anti-Charon hemisphere, similar to the pattern seen for CO ice, so we can tentatively associate both ices with the bright anti-Charon spot in the Buie et al (2010b) albedo map. That N 2 and CO ices would exhibit similar spatial distributions is not surprising, since the two ices have similar volatilities (Brown and Ziegler 1980;Fray and Schmitt 2009) and are completely miscible in one another (Vetter et al 2007). The absorptions of these two ices have also been observed to have very similar longitudinal distributions to one another on Triton, Neptune's large, captured satellite .…”

Section: Nitrogen Icementioning

confidence: 99%

Near-infrared spectral monitoring of Pluto’s ices: Spatial distribution and secular evolution

Grundy

Olkin

Young

et al. 2013

Icarus

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a b s t r a c tWe report results from monitoring Pluto's 0.8 to 2.4 lm reflectance spectrum with IRTF/SpeX on 65 nights over the dozen years from 2001 to 2012. The spectra show vibrational absorption features of simple molecules CH 4 , CO, and N 2 condensed as ices on Pluto's surface. These absorptions are modulated by the planet's 6.39 day rotation period, enabling us to constrain the longitudinal distributions of the three ices. Absorptions of CO and N 2 are concentrated on Pluto's anti-Charon hemisphere, unlike absorptions of less volatile CH 4 ice that are offset by roughly 90°from the longitude of maximum CO and N 2 absorption. In addition to the diurnal variations, the spectra show longer term trends. On decadal timescales, Pluto's stronger CH 4 absorption bands have been getting deeper, while the amplitude of their diurnal variation is diminishing, consistent with additional CH 4 absorption at high northern latitudes rotating into view as the sub-Earth latitude moves north (as defined by the system's angular momentum vector). Unlike the CH 4 absorptions, Pluto's CO and N 2 absorptions appear to be declining over time, suggesting more equatorial or southerly distributions of those species. Comparisons of geometrically-matched pairs of observations favor geometric explanations for the observed secular changes in CO and N 2 absorption, although seasonal volatile transport could be at least partly responsible. The case for a volatile transport contribution to the secular evolution looks strongest for CH 4 ice, despite it being the least volatile of the three ices.

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From optical spectra to phase diagrams—the binary mixture N2–CO

Cited by 15 publications

References 13 publications

On the surface composition of Triton’s southern latitudes

On the surface composition of Triton’s southern latitudes

Regulating the Tautomerization in Covalent Organic Frameworks for Efficient Sacrificial Agent-Free Photocatalytic H₂O₂ Production

Near-infrared spectral monitoring of Pluto’s ices: Spatial distribution and secular evolution

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From optical spectra to phase diagrams—the binary mixture N2–CO

Cited by 15 publications

References 13 publications

On the surface composition of Triton’s southern latitudes

On the surface composition of Triton’s southern latitudes

Regulating the Tautomerization in Covalent Organic Frameworks for Efficient Sacrificial Agent-Free Photocatalytic H2O2 Production

Near-infrared spectral monitoring of Pluto’s ices: Spatial distribution and secular evolution

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Regulating the Tautomerization in Covalent Organic Frameworks for Efficient Sacrificial Agent-Free Photocatalytic H₂O₂ Production