{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,17]],"date-time":"2026-08-17T22:24:00Z","timestamp":1787005440988,"version":"build-2736575974"},"reference-count":49,"publisher":"AIP Publishing","issue":"21","funder":[{"DOI":"10.13039\/100018694","name":"HORIZON EUROPE Marie Sklodowska-Curie Actions","doi-asserted-by":"publisher","award":["101031712"],"award-info":[{"award-number":["101031712"]}],"id":[{"id":"10.13039\/100018694","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100005416","name":"Norges Forskningsr\u00e5d","doi-asserted-by":"publisher","award":["30961"],"award-info":[{"award-number":["30961"]}],"id":[{"id":"10.13039\/501100005416","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2024,6,7]]},"abstract":"<jats:p>Carbon quantum dots have become attractive in various applications, such as drug delivery, biological sensing, photocatalysis, and solar cells. Among these, pH sensing via luminescence lifetime measurements of surface-functionalized carbon dots is one application currently investigated for their long lifetime and autonomous operation. In this article, we explore the theoretical connection between excitation lifetimes and the pH value of the surrounding liquid via the protonation and deprotonation of functional groups. Example calculations applied to m-phenylenediamine, phloroglucinol, and tethered disperse blue 1 are shown by applying a separation approach treating the electronic wave function of functional groups separately from the internal electronic structure of the (large) carbon dot. The bulk of the carbon dot is treated as an environment characterized by its optical spectrum that shifts the transition rates of the functional group. A simple relationship between pH, pKa, and mixed fluorescence lifetime is derived from the transition rates of the protonated and deprotonated states. pH sensitivity improves when the difference in the transition rates is greatest between protonated and deprotonated species, with the greatest sensitivity found where the pKa is close to the pH region of interest. The introduced model can directly be extended to consider multicomponent liquids and multiple protonation states.<\/jats:p>","DOI":"10.1063\/5.0201261","type":"journal-article","created":{"date-parts":[[2024,6,3]],"date-time":"2024-06-03T05:42:11Z","timestamp":1717393331000},"update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":7,"title":["pH-sensitive spontaneous decay of functionalized carbon dots in solutions"],"prefix":"10.1063","volume":"160","author":[{"ORCID":"https:\/\/orcid.org\/0009-0006-0853-7314","authenticated-orcid":false,"given":"Denise","family":"Dilshener","sequence":"first","affiliation":[{"name":"Department of Physics and Technology, University of Bergen 1 , All\u00e9gaten 55, 5007 Bergen, Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3956-6031","authenticated-orcid":false,"given":"Drew F.","family":"Parsons","sequence":"additional","affiliation":[{"name":"Consorzio Interuniversitario per lo Sviluppo dei Sistemi a Grande Interfase (CSGI), Florence, Italy, Unit\u00e0 Operativa University of Cagliari 2 , Italy"},{"name":"Department of Chemical and Geological Sciences, University of Cagliari, Cittadella Universitaria 3 , 09042 Monserrato, CA, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2179-0625","authenticated-orcid":false,"given":"Johannes","family":"Fiedler","sequence":"additional","affiliation":[{"name":"Department of Physics and Technology, University of Bergen 1 , All\u00e9gaten 55, 5007 Bergen, Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"317","published-online":{"date-parts":[[2024,6,3]]},"reference":[{"key":"2024060309394172000_c1","doi-asserted-by":"publisher","first-page":"102","DOI":"10.1016\/j.aquaculture.2009.07.020","article-title":"Modeling the accumulation of CO2 during high density, re-circulating transport of adult Atlantic salmon, Salmo salar, from observations aboard a sea-going commercial live-haul vessel","volume":"296","year":"2009","journal-title":"Aquaculture"},{"key":"2024060309394172000_c2","doi-asserted-by":"publisher","first-page":"89","DOI":"10.1016\/j.aquaeng.2017.02.004","article-title":"The use of novel optode sensor technologies for monitoring dissolved carbon dioxide and ammonia concentrations under live haul conditions","volume":"77","year":"2017","journal-title":"Aquacult. 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