Ultraviolet Actinometry – Determination of the Incident Photon Flux and Quantum Yields for Photochemical Systems Using Low-Pressure and Ultraviolet Light-Emitting Diode Light Sources

Pousty, Dana; Mamane, Hadas; Cohen-Yaniv, Vered; Bolton, James R.

doi:10.2139/ssrn.4069726

Cited by 2 publications

(3 citation statements)

References 7 publications

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“… Before and after the actinometry experiment, position the radiometer/spectroradiometer detector head so that the “calibration plane” (not necessarily the top of the detector head – this plane should be specified in the calibration certificate for the measurement device) is at the level of the top of the washer/ring mask or cardboard plate, and record the measurement device irradiance value. The incident photon flux [ q 0 (253.7) (einstein s –1 )] is then given by

where E (253.7) is the irradiance (W m –2 ) at the center of the hole in the ring mask that is measured with the radiometer or spectroradiometer, the wavelength is according to the peak wavelength of the UV source [11] ,…”

Section: Methods Detailsmentioning

confidence: 99%

“…Use of a monochromatic assumption for a UV-LED using the center wavelength has been compared to a process using numerical integration over the emission spectrum of the UV-LED. A simplification of the calculations has been examined by [11] using this protocol. No significant differences were observed between the monochromatic analysis and the polychromatic analysis, measured by the calibrated spectroradiometer and the ferrioxalate actinometer.…”

Section: Methods Detailsmentioning

confidence: 99%

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Protocol for UVC uridine actinometry

Pousty¹,

Mamane²,

Cohen-Yaniv³

et al. 2023

MethodsX

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Section: Methods Detailsmentioning

confidence: 99%

Section: Methods Detailsmentioning

confidence: 99%

Protocol for UVC uridine actinometry

Pousty¹,

Mamane²,

Cohen-Yaniv³

et al. 2023

MethodsX

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“…However, they are also not broadly polychromatic as medium pressure mercury lamps which have emission lines throughout the 200-300 nm region of the spectrum and beyond. In a recent study, no significant differences were observed between monochromatic peak wavelength analysis and polychromatic analysis for spectroradiometer and ferrioxalate actinometer measurements (Pousty et al, 2022). However, testing using other criteria may show more polychromatic behavior, which would increase with the full width at half-maximum (FWHM) of the LED source tested, spectral response of the radiometer and actinometer, and could have varying impacts based on the action spectrum of microorganisms.…”

Section: Uvc Light Emitting Diodes As Disinfection Light Sourcesmentioning

confidence: 95%

Considerations for determining the performance of ultraviolet light emitting diode fluid disinfection systems

Knight,

Hull

2023

Water Environment Research

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The International Ultraviolet Association (IUVA) Task Force was formed to develop guidelines regarding testing and reporting on performance of UV LED water disinfection systems. The goal was to provide clarity in a guidance document on measuring system performance across the global UV LED water disinfection system market. A review of current performance measurement protocols for mercury lamp based systems shows that the common elements of UV LED system performance measurement protocols should be as follows: specified standard for the amount of pathogen reduction required, the requirement that the validation testing be conducted by a competent facility, and that the system be continually monitored by UV sensors while in use to verify system performance unless pathogen reduction is not claimed. UV LEDs have selectable peak wavelengths, as opposed to mercury lamps that have fixed emission wavelength values. As a result of this difference, the following changes to protocols used to test mercury lamp systems are recommended. First, the use of disinfection benchmarks other than 254 nm dose, such as direct inactivation values, dose benchmarks referenced to 254 nm, and/or dose benchmarks at the UV LED emission wavelength that give the same inactivation as the original 254 nm UV dose benchmark. Second, the use of 254 nm UV water transmittance values as a placeholder, rather than an assumed correct value, for systems under test with LED wavelengths >250 nm and water transmittance values ≥87%. More research is needed for lower wavelengths and UVTs. Third, the recommendation that germicidal response UV sensors be used in UV LED based systems to ensure that the validated disinfection is delivered. Finally, additional LED‐specific considerations were also noted. UV LEDs are also instant‐on devices, making them ideal light sources for systems operated intermittently. Performance testing of systems operated intermittently should include a test to insure that pathogens do not migrate past the UV LEDs while the LEDs are off. UV LED devices have recognized protocols for determining the lifetime of the devices, as well as for measuring other device properties. Caution should be exercised in using these lifetime values for devices in UV disinfection systems, since the thermal environment of the devices may be different for protocol testing and disinfection system operation.Practitioner Points Validation of UVC LED fluid disinfection is necessary for point of use, point of entry, and municipal applications. The emission spectrum properties, considerations and measurements for output over lifetime, and unique system design considerations of UVC LEDs as light sources are factors that must be considered when evaluating fluid disinfection performance. The instant‐on operation, system geometry, validation benchmarks, system sensing, water transmittance, and fouling must also be considered for UVC LED devices when evaluating fluid disinfection performance.

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Ultraviolet Actinometry – Determination of the Incident Photon Flux and Quantum Yields for Photochemical Systems Using Low-Pressure and Ultraviolet Light-Emitting Diode Light Sources

Cited by 2 publications

References 7 publications

Protocol for UVC uridine actinometry

Protocol for UVC uridine actinometry

Considerations for determining the performance of ultraviolet light emitting diode fluid disinfection systems

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