Emission Characteristics of Eu2+ and Eu3+ under X-Ray and Alpha Irradiation in Eu-Doped CaF2 Crystals

Emission Characteristics of Eu2+ and Eu3+ under X-Ray and Alpha Irradiation in Eu-Doped CaF2 Crystals | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Emission Characteristics of Eu 2+ and Eu 3+ under X-Ray and Alpha Irradiation in Eu-Doped CaF 2 Crystals Takashi Iida, Masao Yoshino, Kyoung Jin Kim, Kei Kamada This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7245688/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 01 Sep, 2025 Read the published version in Scientific Reports → Version 1 posted 12 You are reading this latest preprint version Abstract Calcium fluoride crystals doped with europium (CaF2:Eu) have long been used as conventional inorganic scintillators. Their luminescence is primarily attributed to emission from Eu2+ centers, typically around 420 nm. However, it has been reported that increasing the Eu concentration leads to enhanced Eu3+ emission in the wavelength range of 590-700 nm. In this study, CaF2:Eu:Eu crystals with various Eu concentrations (0, 0.3, 1, 2, 3, and 5 mol%) were grown and irradiated with both X-rays and alpha-particles from a 241Am source. Radioluminescence spectra were measured for each excitation condition and compared across samples.The results clearly show that the relative contribution of Eu3+ emission is approximately twice as high under alpha-particle irradiation compared to X-ray excitation. This enhancement was found to be consistent for Eu concentrations above 1%, and independent of the crystal thickness or geometry. To the best of our knowledge, this is the first report demonstrating that the emission intensity ratio of Eu2+/Eu3+ centers in CaF2:Eu scintillators depends on the type of incident radiation. Physical sciences/Chemistry Physical sciences/Materials science Physical sciences/Physics Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 01 Sep, 2025 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 14 Aug, 2025 Reviews received at journal 14 Aug, 2025 Reviews received at journal 14 Aug, 2025 Reviews received at journal 12 Aug, 2025 Reviewers agreed at journal 09 Aug, 2025 Reviewers agreed at journal 08 Aug, 2025 Reviewers agreed at journal 08 Aug, 2025 Reviewers invited by journal 07 Aug, 2025 Editor invited by journal 05 Aug, 2025 Editor assigned by journal 01 Aug, 2025 Submission checks completed at journal 31 Jul, 2025 First submitted to journal 29 Jul, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7245688","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":495966615,"identity":"0ed5958a-c9f3-4086-a9d6-b6a044b87578","order_by":0,"name":"Takashi Iida","email":"data:image/png;base64,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","orcid":"","institution":"University of Tsukuba","correspondingAuthor":true,"prefix":"","firstName":"Takashi","middleName":"","lastName":"Iida","suffix":""},{"id":495966616,"identity":"aa3e481b-741b-4d49-926e-d96ee1710b04","order_by":1,"name":"Masao Yoshino","email":"","orcid":"","institution":"Tohoku University","correspondingAuthor":false,"prefix":"","firstName":"Masao","middleName":"","lastName":"Yoshino","suffix":""},{"id":495966617,"identity":"ecc0cf01-9ebb-4c27-aff0-29b2df3fce8a","order_by":2,"name":"Kyoung Jin Kim","email":"","orcid":"","institution":"Tohoku University","correspondingAuthor":false,"prefix":"","firstName":"Kyoung","middleName":"Jin","lastName":"Kim","suffix":""},{"id":495966618,"identity":"5210d171-7929-4dbe-9080-ade2eec0ff7c","order_by":3,"name":"Kei Kamada","email":"","orcid":"","institution":"Tohoku University","correspondingAuthor":false,"prefix":"","firstName":"Kei","middleName":"","lastName":"Kamada","suffix":""}],"badges":[],"createdAt":"2025-07-29 17:23:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7245688/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7245688/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-025-17570-5","type":"published","date":"2025-09-01T15:57:11+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":90827925,"identity":"17c85037-2b9d-4d46-bd05-62fbce79f43b","added_by":"auto","created_at":"2025-09-08 16:03:27","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":797745,"visible":true,"origin":"","legend":"","description":"","filename":"EuCaF2ColorPID.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7245688/v1_covered_4c7ea311-454d-4e89-b238-4b997e5f01bc.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eEmission Characteristics of Eu\u003csup\u003e2+\u003c/sup\u003e and Eu\u003csup\u003e3+\u003c/sup\u003e under X-Ray and Alpha Irradiation in Eu-Doped CaF\u003csub\u003e2\u003c/sub\u003e Crystals\u003c/p\u003e","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-7245688/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7245688/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Calcium fluoride crystals doped with europium (CaF2:Eu) have long been used as conventional inorganic scintillators. Their luminescence is primarily attributed to emission from Eu2+ centers, typically around 420 nm. However, it has been reported that increasing the Eu concentration leads to enhanced Eu3+ emission in the wavelength range of 590-700 nm. In this study, CaF2:Eu:Eu crystals with various Eu concentrations (0, 0.3, 1, 2, 3, and 5 mol%) were grown and irradiated with both X-rays and alpha-particles from a 241Am source. Radioluminescence spectra were measured for each excitation condition and compared across samples.The results clearly show that the relative contribution of Eu3+ emission is approximately twice as high under alpha-particle irradiation compared to X-ray excitation. This enhancement was found to be consistent for Eu concentrations above 1%, and independent of the crystal thickness or geometry. 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