[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-seo-202060-105":3,"detail-sidebar-cat-0-en-105":81,"doc-detail-202060-en":131},{"code":4,"msg":5,"data":6},0,"ok",{"site_id":7,"language":8,"slug":9,"title":10,"keywords":11,"description":12,"schema_data":13,"social_meta":74,"head_meta":76,"extra_data":78,"updated_unix":80},105,"en","absolute-o3-and-oh-densities-measurement-by-two-beam-uv-led-absorption-spectroscopy-in-atmospheric-pressure-plasmas-thesis","Absolute O3 and OH densities - measurement by two-beam UV-LED absorption spectroscopy in atmospheric pressure plasmas - thesis","","Low temperature atmospheric pressure plasmas (APPs) provide a reactive particle environment and complex chemical-physical interactions near room conditions, enabling both fundamental studies and biomedical applications. This thesis focuses on ozone (O3) and hydroxyl (OH) diagnostics, where accurate density measurements are challenging due to sensitivities to non-plasma parameters and small plasma volumes. A two-beam Mach-Zehnder UV-LED absorption spectroscopy method was developed for O3 density in He-O2 capacitively coupled APPs and applied to biological samples, correlating spatial O3 distributions with bacterial inactivation. Duty-cycle and modulation effects were quantified, anticorrelations with gas temperature were analyzed through plasma chemistry models, OH densities were measured under H2O admixture, and O3 density contributions to CO2-CO conversion processes were examined.",{"@graph":14,"@context":73},[15,34,56],{"@type":16,"itemListElement":17},"BreadcrumbList",[18,23,27,31],{"item":19,"name":20,"@type":21,"position":22},"https://docshare.wps.com","Home","ListItem",1,{"item":24,"name":25,"@type":21,"position":26},"https://docshare.wps.com/document/","Document",2,{"item":28,"name":29,"@type":21,"position":30},"https://docshare.wps.com/document/research-report/","Research & Report",3,{"item":32,"name":10,"@type":21,"position":33},"https://docshare.wps.com/document/absolute-o3-and-oh-densities-measurement-by-two-beam-uv-led-absorption-spectroscopy-in-atmospheric-pressure-plasmas-thesis/202060/",4,{"url":32,"name":10,"@type":35,"image":36,"author":41,"headline":10,"publisher":44,"fileFormat":47,"inLanguage":8,"description":12,"dateModified":48,"datePublished":49,"encodingFormat":47,"isAccessibleForFree":50,"interactionStatistic":51},"DigitalDocument",{"url":37,"@type":38,"width":39,"height":40},"https://docshare.wps.com/thumbnails/absolute-o3-and-oh-densities-measurement-by-two-beam-uv-led-absorption-spectroscopy-in-atmospheric-pressure-plasmas-thesis/202060.png","ImageObject",300,407,{"name":42,"@type":43},"Bill Black","Person",{"url":19,"name":45,"@type":46},"DocShare","Organization","application/pdf","2026-10-23","2026-09-04",true,{"@type":52,"interactionType":53,"userInteractionCount":55},"InteractionCounter",{"@type":54},"ViewAction",14,{"@type":57,"mainEntity":58},"FAQPage",[59,65,69],{"name":60,"@type":61,"acceptedAnswer":62},"What measurement technique is developed in the thesis for ozone density?","Question",{"text":63,"@type":64},"A two-beam UV-LED absorption spectroscopy method using a Mach-Zehnder configuration is developed to measure O3 density in atmospheric pressure plasmas.","Answer",{"name":66,"@type":61,"acceptedAnswer":67},"Why are O3 density measurements considered challenging in APPs?",{"text":68,"@type":64},"Uncertainties can be high because measurements are sensitive to non-plasma parameters and the small plasma volume makes accurate diagnostics difficult.",{"name":70,"@type":61,"acceptedAnswer":71},"How are ozone and hydroxyl densities used in biological and chemical applications?",{"text":72,"@type":64},"The method enables spatial O3 mapping in effluent regions and links radial O3 profiles to bacterial inactivation. With higher H2O vapour admixture, hydroxyl (OH) densities are measured, and O3 density variations are also used to analyze CO2-CO conversion channels.","https://schema.org",{"og:url":32,"og:type":75,"og:title":10,"og:site_name":45,"og:description":12},"article",{"robots":77,"canonical":32},"index,follow",{"doc_id":79,"site_id":7},202060,1788541743,{"code":4,"msg":82,"data":83},"success",[84,88,92,96,101,106,111,115,120,123,127],{"id":22,"doc_module":4,"doc_module_name":25,"category_name":85,"show_sort_weight":86,"slug":87},"Story & Novel",90,"story-novel",{"id":26,"doc_module":4,"doc_module_name":25,"category_name":89,"show_sort_weight":90,"slug":91},"Literature",80,"literature",{"id":33,"doc_module":4,"doc_module_name":25,"category_name":93,"show_sort_weight":94,"slug":95},"Exam",70,"exam",{"id":97,"doc_module":4,"doc_module_name":25,"category_name":98,"show_sort_weight":99,"slug":100},5,"Comic",60,"comic",{"id":102,"doc_module":4,"doc_module_name":25,"category_name":103,"show_sort_weight":104,"slug":105},6,"Technology",50,"technology",{"id":107,"doc_module":4,"doc_module_name":25,"category_name":108,"show_sort_weight":109,"slug":110},7,"Healthcare",40,"healthcare",{"id":112,"doc_module":4,"doc_module_name":25,"category_name":29,"show_sort_weight":113,"slug":114},8,30,"research-report",{"id":116,"doc_module":4,"doc_module_name":25,"category_name":117,"show_sort_weight":118,"slug":119},9,"Religion & Spirituality",20,"religion-spirituality",{"id":118,"doc_module":4,"doc_module_name":25,"category_name":121,"show_sort_weight":118,"slug":122},"World Cup","world-cup",{"id":124,"doc_module":4,"doc_module_name":25,"category_name":125,"show_sort_weight":124,"slug":126},10,"Lifestyle","lifestyle",{"id":128,"doc_module":4,"doc_module_name":25,"category_name":129,"show_sort_weight":97,"slug":130},19,"General","general",{"code":4,"msg":82,"data":132},{"doc_id":79,"user_id":133,"nickname":42,"user_avatar":134,"doc_module":4,"category_id":112,"category_name":29,"doc_title":10,"doc_description":12,"doc_content":135,"file_id":136,"file_url":137,"file_type":138,"file_size":139,"view_count":55,"is_deleted":4,"is_public":22,"is_downloadable":22,"audit_status":22,"page_count":140,"language":141,"language_code":8,"site_id":7,"html_lang":8,"table_of_contents":142,"faqs":143,"seo_title":144,"seo_description":12,"update_tm":80,"read_time":145,"preview_page_count":4},24189269381491,"https://ap-avatar.wpscdn.com/avatar/160000cf11732dd8392?x-image-process=image/resize,m_fixed,w_180,h_180&k=1788146458752108895","Absolute O3 and OH densities  \nmeasurement by two-beam UV-LED absorption spectroscopy in atmospheric  \npressure plasmas  \nApiwat Wijaikhum  \nPhD  \nUniversity of York  \nPhysics  \nSeptember 2016  \nI would like to dedicate this thesis to my beloved family.  \nAbstract  \nLow temperature atmospheric pressure plasmas (APPs) create rich environment of reactive particle species and chemical-physical interactions at close-to-room temperature and ambient pressure which calls for a wide range of fundamental and application studies. APPs for biomedical applications is one of the emerging interdisciplinary researches. Its fundamental mechanisms have been studied using different numerical models and various diagnostic techniques. With hundreds of particle species and complex reactions, each species requires unique measurement techniques. In a typical APP, ozone (O 3), one of the key species in living-cells inactivation, is produced from the complex reaction chain of short-lived oxygen atoms and excited molecules. Measurement and theoretical predictions of O 3 densities can have high uncertainties. The measurements of O3 densities inside the small plasma volume are challenging due to the sensitivity to non-plasma parameters. In this work, two-beam UV-LED absorption spectroscopy has been developed by using a Mach-Zehnder configuration for O3 density measurements on the core of a homogeneous, He-O2 capacitively coupled, 13.56 MHz RF-driven APP. The improved technique allows for high-sensitivity measurement in the order of 10−3 absorption signal with 10−4 of uncertainty. The anticorrelation between O3 density and gas temperature was observed and described based on the plasma chemistry models. For controlling-parameter effect, the duty-cycle in frequency modulations showed a significant influence on the spatial profile of O 3 density in the plasma channel. From an application perspective, the developed technique was able to provide 2DO3 density distribution in the effluent region of a co-axial DBD kHz-driven APPJ when applied to biological samples. The correlation between radial O3 density profiles and bacterial inactivation areas was investigated. In the relatively realistic condition with higher H 2O vapour admixture, hydroxyl (OH) density, which is one of important radical species, can be measured using the UV absorption technique. Thus, the setup has been adjusted in order to measure both species. Furthermore, O 3 density in the CO 2-CO conversion 40.68 MHz RF-driven APP, an important process in chemical research, was observed. The O3 density as a function of plasma power and CO 2 concentration provided a significant contribution to the main production and destruction channels of the conversion processes.  \nTable of Contents  \nAbstract v  \nTable of Contents vii  \nList of Tables xi  \nList of Figures xiii  \nAcknowledgements xix  \nDeclaration xxii  \n1 Introduction 1  \n1.1 Motivation ................................... 1  \n1.2 Thesis outline ................................. 4  \n2 Background 7  \n2.1 Kinetic theory and basic equation of nonthermal LTP ............ 8  \n2.1.1 Boltzmann equation and distribution function ............ 9  \n2.1.2 Governing equation .......................... 10  \n2.2 Elementary processes in gas phase ...................... 12  \n2.2.1 Electron-atom collisions ....................... 12  \n2.2.2 Electron-molecule collisions ..................... 13  \n2.2.3 Heavy-particle collisions ....................... 16  \n2.3 Modeling of non equilibrium low-temperature plasma ............ 17  \n2.3.1 Continuum models .......................... 18  \n2.4 Atmospheric pressure plasmas ........................ 19  \n2.4.1 Fundamentals ............................. 19  \n2.4.2 Atmospheric pressure plasma sources for biomedical applications . 21  \nviii TABLE OF CONTENTS  \n2.4.3 Radio-frequency driven capacitively-coupled APPJ ......... 25  \n2.4.4 Dielectric barrier discharged (DBD) kHz-frequency driven APPJ .. 28  \n2.5 Diagnostic techniques ...","cbCairW5ko84eBWF","https://ap.wps.com/l/cbCairW5ko84eBWF","pdf",6610401,162,"English","# Abstract\n# Introduction\n## Motivation\n## Thesis outline\n# Background\n## Kinetic theory and basic equation of nonthermal LTP\n## Elementary processes in gas phase\n## Modeling of non equilibrium low-temperature plasma\n## Atmospheric pressure plasmas\n## Diagnostic techniques\n# Two-beam UV-LED Absorption Spectroscopy\n## O3 density by UV-LED absorption spectroscopy\n## UV-LED Absorption setup and optical alignment\n## Data acquisition\n## Two-beam technique\n## Spatially resolved O3 density measurement\n# O3 Density Measurements\n## The APP source\n## O3 density and gas temperature\n## Model of gas temperature and O3 density\n# O3 density in pulse-modulated RF atmospheric pressure plasmas\n## Experimental setup\n## O3 density with kHz-frequency modulation of 13.56 MHz RF APP\n## O3 density with duty cycle modulation of 13.56 MHz RF APP\n## Spatial O3 density with duty cycle\n# Spatial O3 density in the effluent region of a co-axial DBD kHz-driven APPJ\n## Absorption principle and Abel inversion\n## Co-axial DBD kHz-driven APPJ and operational control system\n## Experimental setup\n## Surface O3 density distribution with correlation to the bacteria killing zone","[{\"question\":\"What measurement technique is developed in the thesis for ozone density?\",\"answer\":\"A two-beam UV-LED absorption spectroscopy method using a Mach-Zehnder configuration is developed to measure O3 density in atmospheric pressure plasmas.\"},{\"question\":\"Why are O3 density measurements considered challenging in APPs?\",\"answer\":\"Uncertainties can be high because measurements are sensitive to non-plasma parameters and the small plasma volume makes accurate diagnostics difficult.\"},{\"question\":\"How are ozone and hydroxyl densities used in biological and chemical applications?\",\"answer\":\"The method enables spatial O3 mapping in effluent regions and links radial O3 profiles to bacterial inactivation. With higher H2O vapour admixture, hydroxyl (OH) densities are measured, and O3 density variations are also used to analyze CO2-CO conversion channels.\"}]","Absolute O3 and OH densities - measurement by two-beam UV-LED absorption spectroscopy in atmospheric pressure plasmas - thesis | PDF",408]