{
  "annotation_id": "476cca40-6e81-4b5e-90e5-68317dd1c335",
  "date_created": "2026-03-02T18:00:46.302000Z",
  "date_modified": "2026-03-02T18:00:46.302000Z",
  "file_hash": "ddfc960231dd25c154ef642b356a141b3a6c9838bdfbe719f1596681265ff99d",
  "private": false,
  "record": {
    "abstract": "A sensitive laser spectroscopic method has been applied to the quantitative\ndetermination of the isotope ratio of helium at the level of 3He/4He = 10^-7 -\n10^-5. The resonant absorption of 1083 nm laser light by the metastable 3He\natoms in a discharge cell was measured with the frequency modulation saturation\nspectroscopy technique while the abundance of 4He was measured by a direct\nabsorption technique. The results on three different samples extracted from the\natmosphere and commercial helium gas were in good agreement with values\nobtained with mass spectrometry. The achieved 3-sigma detection limit of 3He in\nhelium is 4 x 10^-9. This demonstration required a 200 micro-L STP sample of\nHe. The sensitivity can be further improved, and the required sample size\nreduced, by several orders of magnitude with the addition of cavity enhanced\nspectroscopy.",
    "arxiv_id": "physics/0311121",
    "authors": [
      "L. -B. Wang",
      "P. Mueller",
      "R. J. Holt",
      "Z. -T. Lu",
      "T. P. O\u0027Connor",
      "Y. Sano",
      "N. C. Sturchio"
    ],
    "categories": [
      "physics.atom-ph",
      "physics.geo-ph"
    ],
    "doi": "10.1029/2003GL017242",
    "journal_ref": "Geophysical Research Letters 30, 1592 (2003)",
    "title": "Laser Spectroscopic Measurement of Helium Isotope Ratios",
    "url": "https://arxiv.org/abs/physics/0311121"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "f2b4161c-241c-49c8-b36e-0bcf51519743",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}