{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,16]],"date-time":"2026-02-16T16:00:35Z","timestamp":1771257635968,"version":"3.50.1"},"reference-count":34,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2021,9,27]],"date-time":"2021-09-27T00:00:00Z","timestamp":1632700800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100004937","name":"Bundesministerium f\u00fcr Forschung und Technologie","doi-asserted-by":"publisher","award":["13N14577"],"award-info":[{"award-number":["13N14577"]}],"id":[{"id":"10.13039\/501100004937","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Infrared attenuated total reflection (ATR) spectroscopy is a common laboratory technique for the analysis of highly absorbing liquids or solid samples. However, ATR spectroscopy is rarely found in industrial processes, where inline measurement, continuous operation, and minimal maintenance are important issues. Most materials for mid-infrared (MIR) spectroscopy and specifically for ATR elements do not have either high enough infrared transmission or sufficient mechanical and chemical stability to be exposed to process fluids, abrasive components, and aggressive cleaning agents. Sapphire is the usual choice for infrared wavelengths below 5 \u00b5m, and beyond that, only diamond is an established material. The use of diamond coatings on other ATR materials such as silicon will increase the stability of the sensor and will enable the use of larger ATR elements with increased sensitivity at lower cost for wavelengths above 5 \u00b5m. Theoretical and experimental investigations of the dependence of ATR absorbances on the incidence angle and thickness of nanocrystalline diamond (NCD) coatings on silicon were performed. By optimizing the coating thickness, a substantial amplification of the ATR absorbance can be achieved compared to an uncoated silicon element. Using a compact FTIR instrument, ATR spectra of water, acetonitrile, and propylene carbonate were measured with planar ATR elements made of coated and uncoated silicon. Compared to sapphire, the long wavelength extreme of the spectral range is extended to approximately 8 \u03bcm. With effectively nine ATR reflections, the sensitivity is expected to exceed the performance of typical diamond tip probes.<\/jats:p>","DOI":"10.3390\/s21196442","type":"journal-article","created":{"date-parts":[[2021,9,27]],"date-time":"2021-09-27T22:16:38Z","timestamp":1632780998000},"page":"6442","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Diamond-Coated Silicon ATR Elements for Process Analytics"],"prefix":"10.3390","volume":"21","author":[{"given":"Nicolai","family":"Arndt","sequence":"first","affiliation":[{"name":"Fraunhofer IPM, Georges-K\u00f6hler-Allee 301, D-79110 Freiburg, Germany"}]},{"given":"Carsten","family":"Bolwien","sequence":"additional","affiliation":[{"name":"Fraunhofer IPM, Georges-K\u00f6hler-Allee 301, D-79110 Freiburg, Germany"}]},{"given":"Gerd","family":"Sulz","sequence":"additional","affiliation":[{"name":"Fraunhofer IPM, Georges-K\u00f6hler-Allee 301, D-79110 Freiburg, Germany"}]},{"given":"Frank","family":"K\u00fchnemann","sequence":"additional","affiliation":[{"name":"Fraunhofer IPM, Georges-K\u00f6hler-Allee 301, D-79110 Freiburg, Germany"}]},{"given":"Armin","family":"Lambrecht","sequence":"additional","affiliation":[{"name":"Fraunhofer IPM, Georges-K\u00f6hler-Allee 301, D-79110 Freiburg, Germany"}]}],"member":"1968","published-online":{"date-parts":[[2021,9,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"851","DOI":"10.1364\/JOSA.55.000851","article-title":"Electric Field Strengths at Totally Reflecting Interfaces","volume":"55","author":"Harrick","year":"1965","journal-title":"J. Opt. Soc. Am."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Harrick, N.J. (1987). Internal Reflection Spectroscopy, Harrick Scientific Corporation. [3rd ed.].","DOI":"10.1366\/0003702874868052"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"434","DOI":"10.1366\/0003702011951948","article-title":"Multivariate Calibration for the Determination of Analytes in Urine Using Mid-Infrared Attenuated Total Reflection Spectroscopy","volume":"55","author":"Heise","year":"2001","journal-title":"Appl. Spectrosc."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"729","DOI":"10.1366\/000370206777887071","article-title":"Continuous glucose monitoring by means of fiber-based, mid-infrared laser spectroscopy","volume":"60","author":"Lambrecht","year":"2006","journal-title":"Appl. Spectrosc."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"142","DOI":"10.1007\/s12393-019-09191-2","article-title":"Mid-infrared (MIR) Spectroscopy for Quality Analysis of Liquid Foods","volume":"11","author":"Su","year":"2019","journal-title":"Food Eng. Rev."},{"key":"ref_6","unstructured":"Anton Paar (2020, March 16). Carbo 520 Optical. Available online: https:\/\/www.anton-paar.com\/us-en\/products\/details\/carbo-520-optical\/."},{"key":"ref_7","unstructured":"Centec (2020, March 16). CARBOTEC NIR. Available online: https:\/\/www.centec.de\/sensors\/electronics-semiconductor\/carbotec-nir\/."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"2525","DOI":"10.1038\/srep02525","article-title":"Determination of Chlorinated Hydrocarbons in Water Using Highly Sensitive Mid-Infrared Sensor Technology","volume":"3","author":"Lu","year":"2013","journal-title":"Sci. Rep."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"2070","DOI":"10.1039\/C3AN01457F","article-title":"Broadband spectroscopy with external cavity quantum cascade lasers beyond conventional absorption measurements","volume":"139","author":"Lambrecht","year":"2014","journal-title":"Analyst"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1155\/2019\/5916506","article-title":"Partial Least Squares (PLS) Integrated Fourier Transform Infrared (FTIR) Approach for Prediction of Moisture in Transformer Oil and Lubricating Oil","volume":"2019","author":"Sim","year":"2019","journal-title":"J. Spectrosc."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"184","DOI":"10.1016\/j.cep.2013.04.003","article-title":"Application of ATR-MIR spectroscopy in the pilot plant-Scope and limitations using the example of Paracetamol crystallizations","volume":"70","author":"Helmdach","year":"2013","journal-title":"Chem. Eng. Process. Process. Intensif."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"648","DOI":"10.1080\/03602551003664909","article-title":"In-Line Monitoring of SBR Emulsion Polymerization Using ATR-FTIR Spectroscopy","volume":"49","author":"Li","year":"2010","journal-title":"Polym. Technol. Eng."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Lambrecht, A., Bolwien, C., Erb, J., Fuhr, H., and Sulz, G. (2020). Cylindrical IR-ATR Sensors for Process Analytics. Sensors, 20.","DOI":"10.3390\/s20102917"},{"key":"ref_14","unstructured":"Art Photonics GmbH (2020, March 17). Fiber Optic ATR-Probes. Available online: https:\/\/artphotonics.com\/product\/fiber-optic-atr-probes\/."},{"key":"ref_15","unstructured":"IFS GmbH (2020, March 17). MIR Fiber Probes with Diamond ATR FTIR Technology. Available online: https:\/\/ifs-aachen.de\/."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2314","DOI":"10.1021\/ac504126v","article-title":"Ultrasound-Enhanced Attenuated Total Reflection Mid-infrared Spectroscopy In-Line Probe: Acquisition of Cell Spectra in a Bioreactor","volume":"87","author":"Koch","year":"2015","journal-title":"Anal. Chem."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Steinbach, J.C., Schneider, M., Hauler, O., Lorenz, G., Rebner, K., and Kandelbauer, A. (2020). A Process Analytical Concept for In-Line FTIR Monitoring of Polysiloxane Formation. Polymers, 12.","DOI":"10.3390\/polym12112473"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"12169","DOI":"10.1364\/OE.26.012169","article-title":"Enhanced mid-infrared multi-bounce ATR spectroscopy for online detection of hydrogen peroxide using a supercontinuum laser","volume":"26","author":"Gasser","year":"2018","journal-title":"Opt. Express"},{"key":"ref_19","unstructured":"Pike Technologies Inc. (2021, September 08). Crystal Selection for ATR. Available online: https:\/\/www.piketech.com\/atr-crystal-selection\/."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"6","DOI":"10.1016\/j.diamond.2003.08.014","article-title":"The fabrication of nanocrystalline diamond films using hot filament CVD","volume":"13","author":"Wang","year":"2004","journal-title":"Diam. Relat. Mater."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Neralla, S. (2016). Hot Filament Chemical Vapor Deposition: Enabling the Scalable Synthesis of Bilayer Graphene and Other Carbon Materials. Chemical Vapor Deposition\u2014Recent Advances and Applications in Optical, Solar Cells and Solid State Devices, InTech.","DOI":"10.5772\/61559"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"123526","DOI":"10.1063\/1.1923612","article-title":"High-accuracy, midinfrared refractive index values of silicon","volume":"97","author":"Amirtharaj","year":"2005","journal-title":"J. Appl. Phys."},{"key":"ref_23","unstructured":"(2021, June 21). Refractive Index Database: Optical Constants of C (Carbon, Diamond, Graphite, Graphene, Carbon Nanotubes). Available online: https:\/\/refractiveindex.info\/?shelf=main&book=C&page=Phillip."},{"key":"ref_24","unstructured":"Diamond Materials (2021, June 21). The CVD Diamond Booklet. Available online: https:\/\/www.diamond-materials.com\/en\/downloads."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Milosevic, M. (2012). Internal Reflection and ATR Spectroscopy, Wiley.","DOI":"10.1002\/9781118309742"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"555","DOI":"10.1364\/AO.12.000555","article-title":"Optical Constants of Water in the 200-nm to 200-\\mu m Wavelength Region","volume":"12","author":"Hale","year":"1973","journal-title":"Appl. Opt."},{"key":"ref_27","unstructured":"(2021, September 25). Ansys Canada Ltd, Lumerical 3D\/2D Maxwell\u2019s Solver for Nanophotonic Devices. Available online: https:\/\/www.lumerical.com\/products\/fdtd\/."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Lekner, J. (2016). Theory of Reflection: Reflection and Transmission of Electromagnetic, Particle and Acoustic Waves, Springer. [2nd ed.]. chap. 10.6 and 10.7.","DOI":"10.1007\/978-3-319-23627-8"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Ebermann, M., Neumann, N., Hiller, K., Seifert, M., Meinig, M., and Kurth, S. (2016, January 13\u201318). Tunable MEMS Fabry-P\u00e9rot filters for infrared microspectrometers: A review. Proceedings of MOEMS and Miniaturized Systems XV, SPIE OPTO, San Francisco, CA, USA.","DOI":"10.1117\/12.2209288"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"16","DOI":"10.1515\/teme-2014-0036","article-title":"ATR-Photometer zur Bestimmung der Isocyanatkonzentration in Prozessanwendungen","volume":"82","author":"Theuer","year":"2015","journal-title":"TM\u2014Tech. Mess."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"211","DOI":"10.1016\/j.sna.2007.09.009","article-title":"Design and fabrication steps for a MEMS-based infrared spectrometer using evanescent wave sensing","volume":"142","author":"Wolffenbuttel","year":"2008","journal-title":"Sens. Actuators A Phys."},{"key":"ref_32","unstructured":"Wagner, C. (2021, June 20). Used-Oil Analysis Using a Portable FTIR Spectrometer. Available online: https:\/\/eralytics.com\/instruments\/eraspec-oil-used-oil-analysis\/."},{"key":"ref_33","unstructured":"Foss (2021, June 20). MilkoScan\u2122 FT1. Available online: https:\/\/www.fossanalytics.com\/en\/products\/milkoscan-ft1#Brochures_and_Papers."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"012051","DOI":"10.1088\/1757-899X\/675\/1\/012051","article-title":"Relationship between hardness and optical properties of diamond-like carbon coatings","volume":"675","author":"Suasnavas","year":"2019","journal-title":"IOP Conf. Series Mater. Sci. Eng."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/19\/6442\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T07:05:40Z","timestamp":1760166340000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/19\/6442"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,9,27]]},"references-count":34,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2021,10]]}},"alternative-id":["s21196442"],"URL":"https:\/\/doi.org\/10.3390\/s21196442","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,9,27]]}}}