Broadband transmission EPR spectroscopy.
EPR spectroscopy employs a resonator operating at a single microwave frequency and phase-sensitive detection using modulation of the magnetic field. The X-band spectrometer is the general standard with a frequency in the 9-10 GHz range. Most (bio)molecular EPR spectra are determined by a combination...
| Main Author: | |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Public Library of Science (PLoS)
2013-01-01
|
| Series: | PLoS ONE |
| Online Access: | http://europepmc.org/articles/PMC3605334?pdf=render |
| _version_ | 1831707893114601472 |
|---|---|
| author | Wilfred R Hagen |
| author_facet | Wilfred R Hagen |
| author_sort | Wilfred R Hagen |
| collection | DOAJ |
| description | EPR spectroscopy employs a resonator operating at a single microwave frequency and phase-sensitive detection using modulation of the magnetic field. The X-band spectrometer is the general standard with a frequency in the 9-10 GHz range. Most (bio)molecular EPR spectra are determined by a combination of the frequency-dependent electronic Zeeman interaction and a number of frequency-independent interactions, notably, electron spin - nuclear spin interactions and electron spin - electron spin interactions, and unambiguous analysis requires data collection at different frequencies. Extant and long-standing practice is to use a different spectrometer for each frequency. We explore the alternative of replacing the narrow-band source plus single-mode resonator with a continuously tunable microwave source plus a non-resonant coaxial transmission cell in an unmodulated external field. Our source is an arbitrary wave digital signal generator producing an amplitude-modulated sinusoidal microwave in combination with a broadband amplifier for 0.8-2.7 GHz. Theory is developed for coaxial transmission with EPR detection as a function of cell dimensions and materials. We explore examples of a doublet system, a high-spin system, and an integer-spin system. Long, straigth, helical, and helico-toroidal cells are developed and tested with dilute aqueous solutions of spin label hydroxy-tempo. A detection limit of circa 5 µM HO-tempo in water at 800 MHz is obtained for the present setup, and possibilities for future improvement are discussed. |
| first_indexed | 2024-12-20T21:47:40Z |
| format | Article |
| id | doaj.art-7059e256c2c04d6a960b501a68b338ef |
| institution | Directory Open Access Journal |
| issn | 1932-6203 |
| language | English |
| last_indexed | 2024-12-20T21:47:40Z |
| publishDate | 2013-01-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS ONE |
| spelling | doaj.art-7059e256c2c04d6a960b501a68b338ef2022-12-21T19:25:38ZengPublic Library of Science (PLoS)PLoS ONE1932-62032013-01-0183e5987410.1371/journal.pone.0059874Broadband transmission EPR spectroscopy.Wilfred R HagenEPR spectroscopy employs a resonator operating at a single microwave frequency and phase-sensitive detection using modulation of the magnetic field. The X-band spectrometer is the general standard with a frequency in the 9-10 GHz range. Most (bio)molecular EPR spectra are determined by a combination of the frequency-dependent electronic Zeeman interaction and a number of frequency-independent interactions, notably, electron spin - nuclear spin interactions and electron spin - electron spin interactions, and unambiguous analysis requires data collection at different frequencies. Extant and long-standing practice is to use a different spectrometer for each frequency. We explore the alternative of replacing the narrow-band source plus single-mode resonator with a continuously tunable microwave source plus a non-resonant coaxial transmission cell in an unmodulated external field. Our source is an arbitrary wave digital signal generator producing an amplitude-modulated sinusoidal microwave in combination with a broadband amplifier for 0.8-2.7 GHz. Theory is developed for coaxial transmission with EPR detection as a function of cell dimensions and materials. We explore examples of a doublet system, a high-spin system, and an integer-spin system. Long, straigth, helical, and helico-toroidal cells are developed and tested with dilute aqueous solutions of spin label hydroxy-tempo. A detection limit of circa 5 µM HO-tempo in water at 800 MHz is obtained for the present setup, and possibilities for future improvement are discussed.http://europepmc.org/articles/PMC3605334?pdf=render |
| spellingShingle | Wilfred R Hagen Broadband transmission EPR spectroscopy. PLoS ONE |
| title | Broadband transmission EPR spectroscopy. |
| title_full | Broadband transmission EPR spectroscopy. |
| title_fullStr | Broadband transmission EPR spectroscopy. |
| title_full_unstemmed | Broadband transmission EPR spectroscopy. |
| title_short | Broadband transmission EPR spectroscopy. |
| title_sort | broadband transmission epr spectroscopy |
| url | http://europepmc.org/articles/PMC3605334?pdf=render |
| work_keys_str_mv | AT wilfredrhagen broadbandtransmissioneprspectroscopy |