{"paper":{"title":"Precision Spectroscopy of the Fine Structure in the $\\boldsymbol{a\\;{}^3\\Sigma_u^+(v=0)}$ and $\\boldsymbol{c\\;{}^3\\Sigma_g^+(v=4)}$ States of the Helium Dimer","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":["physics.chem-ph"],"primary_cat":"physics.atom-ph","authors_text":"F. Merkt, M. Holdener, V. Wirth","submitted_at":"2025-08-11T15:03:42Z","abstract_excerpt":"With four electrons, He$_2$ is one of very few molecules for which first-principles quantum-chemical calculations that include the treatment of nonadiabatic, relativistic and quantum-electrodynamics corrections are possible. Precise spectroscopic measurements are needed as references to test these calculations. We report here on a spectroscopic measurement of the $c$ $^3\\Sigma_g^+\\leftarrow a$ $^3\\Sigma_u^+$ electronic transition of $^4$He$_2$ at a precision ($\\Delta \\nu/\\nu$) of $2.5\\times 10^{-10}$ and with full resolution of the rotational, spin-spin and spin-rotational fine structures. The"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2508.08060","kind":"arxiv","version":2},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2508.08060/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}