{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,10]],"date-time":"2026-06-10T16:24:25Z","timestamp":1781108665161,"version":"3.54.1"},"reference-count":0,"publisher":"National Academy of Sciences","issue":"4","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[1977,4]]},"abstract":"<jats:p>\n                    Photon absorption and emission by molecules that undergo radiationless transitions are examined using the single modes of lasers having well-defined coherence properties. Contrary to the usual beliefs, where it is assumed that the molecule is prepared in a Born-Oppenheimer singlet state and then \u201ccrosses-over\u201d to other states (vibrationally \u201chot\u201d singlets and\/or triplets), it is shown\n                    <jats:italic>experimentally<\/jats:italic>\n                    that the true eigenstates of the molecule can be prepared, even in \u201clarge\u201d molecules, if the laser correlation time is relatively long and the molecular relaxation is made slow. On the other hand, lasers with short (psec) correlation time have yielded\n                    <jats:italic>effectively<\/jats:italic>\n                    the singlet Born-Oppenheimer state, which has a much shorter lifetime than the true eigenstates. Effects of magnetic fields and temperature are also reported. The former changes the amount of mixing amongst the Born-Oppenheimer states. The latter, on the other hand, swings the molecule from being \u201csmall\u201d (i.e., sparse vibronic structure with long lifetimes) to being \u201clarge\u201d (i.e., dense statistical distribution of levels) since the relaxation between levels is very effective at high temperatures. Finally, the results of this work show that the words\n                    <jats:italic>fluorescence<\/jats:italic>\n                    and\n                    <jats:italic>phosphorescence<\/jats:italic>\n                    in their strict meaning are misleading if the true eigenstates, which may contain both singlet and triplet character, are prepared.\n                  <\/jats:p>","DOI":"10.1073\/pnas.74.4.1310","type":"journal-article","created":{"date-parts":[[2006,5,31]],"date-time":"2006-05-31T03:29:46Z","timestamp":1149046186000},"page":"1310-1314","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":18,"title":["Radiationless relaxation in \u201clarge\u201d molecules: Experimental evidence for preparation of true molecular eigenstates and Born-Oppenheimer states by a coherent light source"],"prefix":"10.1073","volume":"74","author":[{"given":"A. H.","family":"Zewail","sequence":"first","affiliation":[{"name":"Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"T. E.","family":"Orlowski","sequence":"additional","affiliation":[{"name":"Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"K. E.","family":"Jones","sequence":"additional","affiliation":[{"name":"Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[1977,4]]},"container-title":["Proceedings of the National Academy of Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pnas.org\/doi\/pdf\/10.1073\/pnas.74.4.1310","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,4,13]],"date-time":"2022-04-13T11:12:47Z","timestamp":1649848367000},"score":1,"resource":{"primary":{"URL":"https:\/\/pnas.org\/doi\/full\/10.1073\/pnas.74.4.1310"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1977,4]]},"references-count":0,"journal-issue":{"issue":"4","published-print":{"date-parts":[[1977,4]]}},"alternative-id":["10.1073\/pnas.74.4.1310"],"URL":"https:\/\/doi.org\/10.1073\/pnas.74.4.1310","relation":{},"ISSN":["0027-8424","1091-6490"],"issn-type":[{"value":"0027-8424","type":"print"},{"value":"1091-6490","type":"electronic"}],"subject":[],"published":{"date-parts":[[1977,4]]},"assertion":[{"value":"1977-04-01","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}