{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T16:01:07Z","timestamp":1790092867202,"version":"4.0.1"},"reference-count":34,"publisher":"American Chemical Society (ACS)","issue":"37","license":[{"start":{"date-parts":[[2026,9,4]],"date-time":"2026-09-04T00:00:00Z","timestamp":1788480000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100009055","name":"?anakkale Onsekiz Mart ?niversitesi","doi-asserted-by":"publisher","award":["FBA-2023-4342"],"award-info":[{"award-number":["FBA-2023-4342"]}],"id":[{"id":"10.13039\/100009055","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,9,22]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Accurate knowledge of the refractive index (n) and extinction coefficient (\u03ba) dispersions is essential for understanding the optical response of thin-film materials used in photovoltaics, optoelectronics, and related photonic applications. However, transmission-based dispersion extraction becomes unreliable for turbid, colloidal, nanostructured, or strongly absorbing thin films, where low transmission or scattering prevents accurate spectral evaluation. In this work, we introduce a reflectance-only framework based on the Paul wavelet transform applied to normal-incidence reflectance spectra. The method exploits repetition frequency analysis of interference fringes to retrieve continuous dispersions of n and \u03ba without requiring a predefined dispersion model. The wavelet order provides explicit control over the joint spectral-Fourier resolution, allowing optimization for a given data set. The approach is validated through simulation studies and a noisy signal test with 10% additive random noise, and benchmarked against Minkov\u2019s reflectance-based envelope\/extrema method. Under noisy conditions, the proposed method preserves the refractive index trend close to the reference behavior, whereas the envelope-based approach shows larger deviations. The extinction coefficient is more sensitive to noise in both methods, although the wavelet-based retrieval remains comparatively stable. Experimental validation on a CdS thin film demonstrates consistency of the refractive index dispersion with literature data, while deviations in the extinction coefficient are attributed to its sensitivity to absorption-related and microstructural variations. The method requires independent film thickness information, as in all interference-based approaches, but is otherwise nondestructive and model-free, making it suitable for a broad range of thin-film systems including doped semiconductors, colloidal nanostructures, and hybrid organic\u2013inorganic materials where conventional transmission or ellipsometric methods are difficult to apply.<\/jats:p>","DOI":"10.1021\/acsomega.6c00253","type":"journal-article","created":{"date-parts":[[2026,9,4]],"date-time":"2026-09-04T09:01:56Z","timestamp":1788512516000},"page":"54965-54973","source":"Crossref","is-referenced-by-count":0,"title":["Reflectance-Only\nRetrieval of Refractive Index and\nExtinction Coefficient Dispersions in an Absorbing Thin Film via a\nPaul-Wavelet Repetition-Frequency Method"],"prefix":"10.1021","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6820-3889","authenticated-orcid":true,"given":"Emre","family":"Coskun","sequence":"first","affiliation":[{"name":"C\u0327anakkale Onsekiz Mart University , , ,","place":["C\u0327anakkale, Turkey, 17100"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Cansu","family":"Emir","sequence":"additional","affiliation":[{"name":"Atilim University , , ,","place":["Ankara, Turkey, 06830"]},{"name":"Gazi University , , ,","place":["Ankara, Turkey, 06500"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Erhan","family":"Tiryaki","sequence":"additional","affiliation":[{"name":"Marelli MAKO Turkey Elektrik Sanayi ve Ticaret A.S\u0327 , ,","place":["Bursa, Turkey, 16220"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Makbule","family":"Terlemezoglu","sequence":"additional","affiliation":[{"name":"Gazi University , , ,","place":["Ankara, Turkey, 06560"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9542-5121","authenticated-orcid":true,"given":"Mehmet","family":"Parlak","sequence":"additional","affiliation":[{"name":"Middle East Technical University , , ,","place":["Ankara, Turkey, 06800"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,9,4]]},"reference":[{"issue":"18","key":"2026092210575965700_cit1","doi-asserted-by":"publisher","first-page":"8718","DOI":"10.1039\/C9NR02792K","article-title":"Gold Nanorods as a High-Pressure Sensor of Phase Transitions\nand Refractive-Index Gauge","volume":"11","author":"Runowski","year":"2019","journal-title":"Nanoscale"},{"issue":"7","key":"2026092210575965700_cit2","doi-asserted-by":"publisher","first-page":"1587","DOI":"10.1021\/acs.jpclett.9b00636","article-title":"Monodisperse Gold Nanorods for High-Pressure\nRefractive Index Sensing","volume":"10","author":"Marti\u0301n-Sa\u0301nchez","year":"2019","journal-title":"J. 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