Optimal dielectric and cavity configurations for improving the efficiency of electron paramagnetic resonance probes
[Display omitted] •A probe made of a dielectric (DR) and a cavity (CV) is studied.•Its Λ efficiency in terms of the ΛDR and ΛCV components is derived.•For CVs with a high Q, the DR with highest ΛDR. gives the best Λ.•For CVs with a low Q, the DR with highest εr gives the best Λ.•For lossy samples or...
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| Veröffentlicht in: | Journal of magnetic resonance (1997) 2014-08, Vol.245, p.50-57 |
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| container_title | Journal of magnetic resonance (1997) |
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| creator | Elnaggar, Sameh Y. Tervo, Richard Mattar, Saba M. |
| description | [Display omitted]
•A probe made of a dielectric (DR) and a cavity (CV) is studied.•Its Λ efficiency in terms of the ΛDR and ΛCV components is derived.•For CVs with a high Q, the DR with highest ΛDR. gives the best Λ.•For CVs with a low Q, the DR with highest εr gives the best Λ.•For lossy samples or DRs, the shield can improve Λ.
An electron paramagnetic resonance (EPR) spectrometer’s lambda efficiency parameter (Λ) is one of the most important parameters that govern its sensitivity. It is studied for an EPR probe consisting of a dielectric resonator (DR) in a cavity (CV). Expressions for Λ are derived in terms of the probe’s individual DR and CV components, Λ1 and Λ2 respectively. Two important cases are considered. In the first, a probe consisting of a CV is improved by incorporating a DR. The sensitivity enhancement depends on the relative rather than the absolute values of the individual components. This renders the analysis general. The optimal configuration occurs when the CV and DR modes are nearly degenerate. This configuration guarantees that the probe can be easily coupled to the microwave bridge while maintaining a large Λ. It is shown that for a lossy CV with a small quality factor Q2, one chooses a DR that has the highest filling factor, η1, regardless of its Λ1 and Q1. On the other hand, if the CV has a large Q2, the optimum DR is the one which has the highest Λ1. This is regardless of its η1 and relative dielectric constant, ɛr. When the quality factors of both the CV and DR are comparable, the lambda efficiency is reduced by a factor of 2. Thus the signal intensity for an unsaturated sample is cut in half. The second case is the design of an optimum shield to house a DR. Besides preventing radiation leakage, it is shown that for a high loss DR, the shield can actually boost Λ above the DR value. This can also be very helpful for relatively low efficiency dielectrics as well as lossy samples, such as polar liquids. |
| doi_str_mv | 10.1016/j.jmr.2014.05.011 |
| format | Article |
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•A probe made of a dielectric (DR) and a cavity (CV) is studied.•Its Λ efficiency in terms of the ΛDR and ΛCV components is derived.•For CVs with a high Q, the DR with highest ΛDR. gives the best Λ.•For CVs with a low Q, the DR with highest εr gives the best Λ.•For lossy samples or DRs, the shield can improve Λ.
An electron paramagnetic resonance (EPR) spectrometer’s lambda efficiency parameter (Λ) is one of the most important parameters that govern its sensitivity. It is studied for an EPR probe consisting of a dielectric resonator (DR) in a cavity (CV). Expressions for Λ are derived in terms of the probe’s individual DR and CV components, Λ1 and Λ2 respectively. Two important cases are considered. In the first, a probe consisting of a CV is improved by incorporating a DR. The sensitivity enhancement depends on the relative rather than the absolute values of the individual components. This renders the analysis general. The optimal configuration occurs when the CV and DR modes are nearly degenerate. This configuration guarantees that the probe can be easily coupled to the microwave bridge while maintaining a large Λ. It is shown that for a lossy CV with a small quality factor Q2, one chooses a DR that has the highest filling factor, η1, regardless of its Λ1 and Q1. On the other hand, if the CV has a large Q2, the optimum DR is the one which has the highest Λ1. This is regardless of its η1 and relative dielectric constant, ɛr. When the quality factors of both the CV and DR are comparable, the lambda efficiency is reduced by a factor of 2. Thus the signal intensity for an unsaturated sample is cut in half. The second case is the design of an optimum shield to house a DR. Besides preventing radiation leakage, it is shown that for a high loss DR, the shield can actually boost Λ above the DR value. This can also be very helpful for relatively low efficiency dielectrics as well as lossy samples, such as polar liquids.</description><identifier>ISSN: 1090-7807</identifier><identifier>EISSN: 1096-0856</identifier><identifier>DOI: 10.1016/j.jmr.2014.05.011</identifier><identifier>PMID: 24937043</identifier><language>eng</language><publisher>United States: Elsevier Inc</publisher><subject>Cavity resonators ; Coupled mode theory ; Coupled modes ; Coupling coefficients ; Dielectric resonators ; Dielectrics ; Efficiency parameter ; Electron paramagnetic resonance ; Electron Spin Resonance Spectroscopy - instrumentation ; Equipment Design ; Field distributions ; Filling factor ; Finite Element Analysis ; Finite element methods ; Houses ; Magnetic resonance ; Microwaves ; Optimization ; Quality factor ; Resonant cavity ; Resonator modes ; Sensitivity and Specificity ; Shields ; Signal-To-Noise Ratio ; Spectrometer sensitivity</subject><ispartof>Journal of magnetic resonance (1997), 2014-08, Vol.245, p.50-57</ispartof><rights>2014 Elsevier Inc.</rights><rights>Copyright © 2014 Elsevier Inc. All rights reserved.</rights><lds50>peer_reviewed</lds50><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-c386t-f853f953936f245c556035b8a7e6cf099a848c6856622ee8bf53b44ea15ca7253</citedby><cites>FETCH-LOGICAL-c386t-f853f953936f245c556035b8a7e6cf099a848c6856622ee8bf53b44ea15ca7253</cites></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><linktohtml>$$Uhttps://dx.doi.org/10.1016/j.jmr.2014.05.011$$EHTML$$P50$$Gelsevier$$H</linktohtml><link.rule.ids>314,780,784,3550,27924,27925,45995</link.rule.ids><backlink>$$Uhttps://www.ncbi.nlm.nih.gov/pubmed/24937043$$D View this record in MEDLINE/PubMed$$Hfree_for_read</backlink></links><search><creatorcontrib>Elnaggar, Sameh Y.</creatorcontrib><creatorcontrib>Tervo, Richard</creatorcontrib><creatorcontrib>Mattar, Saba M.</creatorcontrib><title>Optimal dielectric and cavity configurations for improving the efficiency of electron paramagnetic resonance probes</title><title>Journal of magnetic resonance (1997)</title><addtitle>J Magn Reson</addtitle><description>[Display omitted]
•A probe made of a dielectric (DR) and a cavity (CV) is studied.•Its Λ efficiency in terms of the ΛDR and ΛCV components is derived.•For CVs with a high Q, the DR with highest ΛDR. gives the best Λ.•For CVs with a low Q, the DR with highest εr gives the best Λ.•For lossy samples or DRs, the shield can improve Λ.
An electron paramagnetic resonance (EPR) spectrometer’s lambda efficiency parameter (Λ) is one of the most important parameters that govern its sensitivity. It is studied for an EPR probe consisting of a dielectric resonator (DR) in a cavity (CV). Expressions for Λ are derived in terms of the probe’s individual DR and CV components, Λ1 and Λ2 respectively. Two important cases are considered. In the first, a probe consisting of a CV is improved by incorporating a DR. The sensitivity enhancement depends on the relative rather than the absolute values of the individual components. This renders the analysis general. The optimal configuration occurs when the CV and DR modes are nearly degenerate. This configuration guarantees that the probe can be easily coupled to the microwave bridge while maintaining a large Λ. It is shown that for a lossy CV with a small quality factor Q2, one chooses a DR that has the highest filling factor, η1, regardless of its Λ1 and Q1. On the other hand, if the CV has a large Q2, the optimum DR is the one which has the highest Λ1. This is regardless of its η1 and relative dielectric constant, ɛr. When the quality factors of both the CV and DR are comparable, the lambda efficiency is reduced by a factor of 2. Thus the signal intensity for an unsaturated sample is cut in half. The second case is the design of an optimum shield to house a DR. Besides preventing radiation leakage, it is shown that for a high loss DR, the shield can actually boost Λ above the DR value. This can also be very helpful for relatively low efficiency dielectrics as well as lossy samples, such as polar liquids.</description><subject>Cavity resonators</subject><subject>Coupled mode theory</subject><subject>Coupled modes</subject><subject>Coupling coefficients</subject><subject>Dielectric resonators</subject><subject>Dielectrics</subject><subject>Efficiency parameter</subject><subject>Electron paramagnetic resonance</subject><subject>Electron Spin Resonance Spectroscopy - instrumentation</subject><subject>Equipment Design</subject><subject>Field distributions</subject><subject>Filling factor</subject><subject>Finite Element Analysis</subject><subject>Finite element methods</subject><subject>Houses</subject><subject>Magnetic resonance</subject><subject>Microwaves</subject><subject>Optimization</subject><subject>Quality factor</subject><subject>Resonant cavity</subject><subject>Resonator modes</subject><subject>Sensitivity and Specificity</subject><subject>Shields</subject><subject>Signal-To-Noise Ratio</subject><subject>Spectrometer sensitivity</subject><issn>1090-7807</issn><issn>1096-0856</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2014</creationdate><recordtype>article</recordtype><sourceid>EIF</sourceid><recordid>eNqFkcFu3CAURVGUqpNM-gHdVCy7sfswBtvqqorSNlKkbJo1wvgxYWTDBDwjzd-XGSddNitYnHfhnUvIZwYlAya_bcvtFMsKWF2CKIGxC3LFoJMFtEJenu9QNC00K3Kd0hYyIRr4SFZV3fEGan5F0uNudpMe6eBwRDNHZ6j2AzX64OYjNcFbt9lHPbvgE7UhUjftYjg4v6HzM1K01hmH3hxpsHSJCJ7udNST3nicc17EFLz2Bmme7DHdkA9Wjwk_vZ5r8vTz7s_t7-Lh8df97Y-HwvBWzoVtBbed4B2XtqqFEUICF32rG5TGQtfptm6NzKvKqkJseyt4X9eomTC6qQRfk69Lbn72ZY9pVpNLBsdRewz7pJjM6oBxVr-PClHxJn8LMsoW1MSQUkSrdjEbjEfFQJ1qUVuVa1GnWhQIlaXnmS-v8ft-wuHfxFsPGfi-AJh9HBxGlc5WcXAxK1VDcP-J_wt6bZ7A</recordid><startdate>20140801</startdate><enddate>20140801</enddate><creator>Elnaggar, Sameh Y.</creator><creator>Tervo, Richard</creator><creator>Mattar, Saba M.</creator><general>Elsevier Inc</general><scope>CGR</scope><scope>CUY</scope><scope>CVF</scope><scope>ECM</scope><scope>EIF</scope><scope>NPM</scope><scope>AAYXX</scope><scope>CITATION</scope><scope>7X8</scope><scope>7U5</scope><scope>8FD</scope><scope>L7M</scope></search><sort><creationdate>20140801</creationdate><title>Optimal dielectric and cavity configurations for improving the efficiency of electron paramagnetic resonance probes</title><author>Elnaggar, Sameh Y. ; Tervo, Richard ; Mattar, Saba M.</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-c386t-f853f953936f245c556035b8a7e6cf099a848c6856622ee8bf53b44ea15ca7253</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2014</creationdate><topic>Cavity resonators</topic><topic>Coupled mode theory</topic><topic>Coupled modes</topic><topic>Coupling coefficients</topic><topic>Dielectric resonators</topic><topic>Dielectrics</topic><topic>Efficiency parameter</topic><topic>Electron paramagnetic resonance</topic><topic>Electron Spin Resonance Spectroscopy - instrumentation</topic><topic>Equipment Design</topic><topic>Field distributions</topic><topic>Filling factor</topic><topic>Finite Element Analysis</topic><topic>Finite element methods</topic><topic>Houses</topic><topic>Magnetic resonance</topic><topic>Microwaves</topic><topic>Optimization</topic><topic>Quality factor</topic><topic>Resonant cavity</topic><topic>Resonator modes</topic><topic>Sensitivity and Specificity</topic><topic>Shields</topic><topic>Signal-To-Noise Ratio</topic><topic>Spectrometer sensitivity</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Elnaggar, Sameh Y.</creatorcontrib><creatorcontrib>Tervo, Richard</creatorcontrib><creatorcontrib>Mattar, Saba M.</creatorcontrib><collection>Medline</collection><collection>MEDLINE</collection><collection>MEDLINE (Ovid)</collection><collection>MEDLINE</collection><collection>MEDLINE</collection><collection>PubMed</collection><collection>CrossRef</collection><collection>MEDLINE - Academic</collection><collection>Solid State and Superconductivity Abstracts</collection><collection>Technology Research Database</collection><collection>Advanced Technologies Database with Aerospace</collection><jtitle>Journal of magnetic resonance (1997)</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Elnaggar, Sameh Y.</au><au>Tervo, Richard</au><au>Mattar, Saba M.</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Optimal dielectric and cavity configurations for improving the efficiency of electron paramagnetic resonance probes</atitle><jtitle>Journal of magnetic resonance (1997)</jtitle><addtitle>J Magn Reson</addtitle><date>2014-08-01</date><risdate>2014</risdate><volume>245</volume><spage>50</spage><epage>57</epage><pages>50-57</pages><issn>1090-7807</issn><eissn>1096-0856</eissn><abstract>[Display omitted]
•A probe made of a dielectric (DR) and a cavity (CV) is studied.•Its Λ efficiency in terms of the ΛDR and ΛCV components is derived.•For CVs with a high Q, the DR with highest ΛDR. gives the best Λ.•For CVs with a low Q, the DR with highest εr gives the best Λ.•For lossy samples or DRs, the shield can improve Λ.
An electron paramagnetic resonance (EPR) spectrometer’s lambda efficiency parameter (Λ) is one of the most important parameters that govern its sensitivity. It is studied for an EPR probe consisting of a dielectric resonator (DR) in a cavity (CV). Expressions for Λ are derived in terms of the probe’s individual DR and CV components, Λ1 and Λ2 respectively. Two important cases are considered. In the first, a probe consisting of a CV is improved by incorporating a DR. The sensitivity enhancement depends on the relative rather than the absolute values of the individual components. This renders the analysis general. The optimal configuration occurs when the CV and DR modes are nearly degenerate. This configuration guarantees that the probe can be easily coupled to the microwave bridge while maintaining a large Λ. It is shown that for a lossy CV with a small quality factor Q2, one chooses a DR that has the highest filling factor, η1, regardless of its Λ1 and Q1. On the other hand, if the CV has a large Q2, the optimum DR is the one which has the highest Λ1. This is regardless of its η1 and relative dielectric constant, ɛr. When the quality factors of both the CV and DR are comparable, the lambda efficiency is reduced by a factor of 2. Thus the signal intensity for an unsaturated sample is cut in half. The second case is the design of an optimum shield to house a DR. Besides preventing radiation leakage, it is shown that for a high loss DR, the shield can actually boost Λ above the DR value. This can also be very helpful for relatively low efficiency dielectrics as well as lossy samples, such as polar liquids.</abstract><cop>United States</cop><pub>Elsevier Inc</pub><pmid>24937043</pmid><doi>10.1016/j.jmr.2014.05.011</doi><tpages>8</tpages></addata></record> |
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| subjects | Cavity resonators Coupled mode theory Coupled modes Coupling coefficients Dielectric resonators Dielectrics Efficiency parameter Electron paramagnetic resonance Electron Spin Resonance Spectroscopy - instrumentation Equipment Design Field distributions Filling factor Finite Element Analysis Finite element methods Houses Magnetic resonance Microwaves Optimization Quality factor Resonant cavity Resonator modes Sensitivity and Specificity Shields Signal-To-Noise Ratio Spectrometer sensitivity |
| title | Optimal dielectric and cavity configurations for improving the efficiency of electron paramagnetic resonance probes |
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