Novel bandpass filter for far UV-C emitting radiation sources
Jan-Niklas Keil1, Heike Kätker1, René T Wegh2
1Department of Chemical Engineering, FH Münster University of Applied Sciences, Stegerwaldstrasse 39, D-48565, Steinfurt, Germany.
Optical Materials
|May 16, 2023
Summary
Researchers developed a novel phosphor filter using bismuth and holmium-doped ortho-borates for far UV-C disinfection lamps. This cost-effective filter effectively suppresses unwanted wavelengths, enhancing safety for use in occupied spaces.
Area of Science:
- Photonic materials science
- Applied physics
- Microbiology
Background:
- Far UV-C radiation (<230 nm) offers effective microbial inactivation, including SARS-CoV-2, with limited human tissue penetration.
- KrCl* excimer lamps (222 nm) are promising far-UV sources but emit unwanted longer wavelengths requiring suppression.
- Current dichroic filters are effective but expensive; phosphor-based alternatives offer a potentially cheaper solution.
Purpose of the Study:
- To explore and develop a cost-effective phosphor-based filter for KrCl* excimer lamps.
- To synthesize and characterize novel materials for efficient UV-C wavelength filtering.
- To evaluate the performance of phosphor filters in enhancing safety for far UV-C disinfection.
Main Methods:
- Synthesis and characterization of various Bi3+-doped ortho-borate compounds.
- Identification of Y0.24Lu0.75Bi0.01BO3 for optimal UV-C absorption.
- Co-doping with Ho3+ to suppress unwanted UV-B emission via energy transfer.
- Formulation of coating suspensions and application of filter layers.
- Evaluation of filter efficiency and gain factor compared to dichroic filters.
Main Results:
- Bi3+-doped ortho-borates with pseudo-vaterite structure showed excellent UV-C absorption.
- Y0.24Lu0.75Bi0.01BO3 exhibited the best absorption spectrum around 222 nm.
- Ho3+ co-doping effectively suppressed UV-B emission, with Ho0.24Lu0.75Bi0.01BO3 as the top candidate.
- Achieved a gain factor of up to 2.33 with the Ho3+-containing phosphor filter.
Conclusions:
- Ho0.24Lu0.75Bi0.01BO3 is a promising, cost-effective phosphor material for KrCl* far UV-C lamps.
- The developed phosphor filters offer a significant improvement in exposure limits.
- This research paves the way for safer and more accessible far UV-C disinfection technologies.
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