{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T15:05:46Z","timestamp":1789657546177,"version":"4.0.1"},"reference-count":46,"publisher":"American Chemical Society (ACS)","issue":"37","license":[{"start":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T00:00:00Z","timestamp":1788825600000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-029"},{"start":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T00:00:00Z","timestamp":1788825600000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-037"},{"start":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T00:00:00Z","timestamp":1788825600000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-045"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,9,17]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Superthermal (\u201chot\u201d) oxygen atoms deposit their energy in planetary upper atmospheres and in hypersonic shock layers through collisions with N2, but the rate at which they do so is set not by the magnitude of the collision cross section, which is dominated by forward diffraction, but by transport-weighted moments of the differential cross section (DCS). We derive momentum-transfer and viscosity cross sections, mean collisional deflections, and energy-relaxation rates for O(3P) + N2 from our previously reported quantum coupled-channel DCSs, for 16O, 17O, and 18O over collision energies 0.31\u20134.0 eV. The momentum-transfer cross section is well represented by \u03c3m = 9.90 \u00d7 10\u201316Ek\u20130.385 cm2 (Ek in eV), a factor of 28\u201332 below the collision cross section, with mean deflection \u27e81 \u2013 cos \u03b8\u27e9 = 0.031\u20130.036. Rotationally inelastic channels supply 72\u201388% of it, so transport treatments built on elastic angular distributions underestimate the stopping power of N2 several-fold. The heavy-isotope enhancement of the integral elastic cross section (1\u20135%) does not survive transport weighting. \u03c3m is isotope-independent to within 0.4% above 0.6 eV, because the enhancement resides in the transport-inert forward cone, so isotopic effects in thermalization are kinematic (+2.9% recoil per collision for 18O relative to 16O). The mean energy loss per collision rises from 10 to 68 meV, and Monte Carlo slowing down gives \u2248120 collisions and a stopping column of 3.7 \u00d7 1015 cm\u20132 to thermalize a nascent 3.48 eV atom in pure N2, some 20 times the isotropic hard-sphere estimate. A loss law that satisfies detailed balance in a 460 K bath raises the number of collisions by 6.5%. Comparing the isotopes at equal velocity instead of equal energy shifts \u03c3m by 1.5\u20132.8%, and this shift is purely kinematic.<\/jats:p>","DOI":"10.1021\/acs.jpca.6c05290","type":"journal-article","created":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T10:01:57Z","timestamp":1788861717000},"page":"7441-7449","source":"Crossref","is-referenced-by-count":0,"title":["Transport Cross\nSections and Collisional Energy Relaxation\nof Superthermal O(3P) Atoms in N2 for Planetary\nAeronomy"],"prefix":"10.1021","volume":"130","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0180-0539","authenticated-orcid":true,"given":"Sanchit","family":"Kumar","sequence":"first","affiliation":[{"name":"King Abdullah University of Science and Technology , , ,","place":["Thuwal, Saudi Arabia, 23955-6900"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,9,8]]},"reference":[{"key":"2026091708520194600_cit1","doi-asserted-by":"publisher","first-page":"6946","DOI":"10.1063\/1.452394","article-title":"Calculated potential surfaces for the reactions: O+N2\u2192NO+N and N+O2\u2192NO+O","volume":"86","author":"Walch","year":"1987","journal-title":"J. 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Phys."},{"key":"2026091708520194600_cit5","doi-asserted-by":"publisher","first-page":"3273","DOI":"10.1021\/acs.jpca.1c10346","article-title":"Rovibrational-specific QCT and master equation study\non N2 (X1\u03a3g+)+ O (3P) and NO (X2\u03a0)+ N (4S) systems in high-energy\ncollisions","volume":"126","author":"Jo","year":"2022","journal-title":"J. Phys. Chem. A"},{"key":"2026091708520194600_cit6","doi-asserted-by":"publisher","DOI":"10.1039\/D0CP02509G","article-title":"Accurate reproducing\nkernel-based potential energy surfaces for the triplet ground states\nof N2O and dynamics for the N+ NO\u2194 O+ N2 and N2+ O\u2192 2N+ O reactions","volume":"22","author":"Koner","year":"2020","journal-title":"Phys. Chem. Chem. Phys."},{"key":"2026091708520194600_cit7","doi-asserted-by":"publisher","DOI":"10.1063\/1.4938241","article-title":"Global\ntriplet potential energy surfaces for the N2 (X1\u03a3)+ O (3P)\u2192 NO (X2\u03a0)+ N\n(4S) reaction","volume":"144","author":"Lin","year":"2016","journal-title":"J. Chem. Phys."},{"key":"2026091708520194600_cit8","doi-asserted-by":"publisher","first-page":"2392","DOI":"10.1039\/C6CP07142B","article-title":"Reactive collisions for NO(2\u03a0) + N(4S) at temperatures relevant to the hypersonic\nflight regime","volume":"19","author":"Denis-Alpizar","year":"2017","journal-title":"Phys. Chem. Chem. Phys."},{"key":"2026091708520194600_cit9","doi-asserted-by":"publisher","first-page":"993","DOI":"10.1029\/92GL00050","article-title":"Infrared emissions\narising from the reactions of fast O\/O+ with N2","volume":"19","author":"Upschulte","year":"1992","journal-title":"Geophys. Res. 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