CC BY
2*
ALT'23
The 30th International Conference on Advanced Laser Technologies
LM-O-13
Laser synthesis of ruby nanoparticles for photo-conversion of solar
spectrum
K.O. Aiyyzhy*1, E.V. Barmina1, I.I. Rakov1, G.A. Shafeev1
1-Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilova str. 38, 119991 Moscow, Russia
*aiyyzhy@phystech. edu
Solar radiation is used by plants for photosynthesis. The most demanded part for the efficient proliferation of land plants (embryophytes) is in the red range of the spectrum from 600 nm to 780 nm [1]. This is especially true for land plants grown in greenhouses in terrestrial areas of risky agriculture [2,3]. However, the fraction of radiation in this range of the solar spectrum is rather small. Therefore, the photoconversion of solar radiation to the red region is highly desirable to increase the photosynthetic efficiency factor. Existing coatings based on semiconductors (CdS, CdSe) or organic dyes convert solar radiation to the red region. However, these coatings are not stable under sunlight and are rapidly degraded. Ruby-based materials can become an alternative to these converters, since ruby has a high photostability and is characterized by strong photoluminescence near 695 nm.
In this work ruby particles at various Cr3+ (2 - 10%) content were obtained by laser heating of a mixture of industrial Al2O3 and Cr2O3 micro-powders in air. The mixture was exposed to quasi-continuous wave radiation of a Nd:YAG laser with wavelength of 1064 nm modulated at frequency of 200 kHz by 1.5 ^s pulses. The estimated diameter of the laser spot was 100 ^m, average power of the laser radiation was 15 W, which corresponds to power density of 150 kW/cm2 on the surface of the mixture. Laser-heated ruby grains have average size of 0.5-1 mm. Further laser fragmentation of these grains in isopropanol was applied to reduce their size. The same laser source was used for fragmentation: Q-switch mode, the repetition rate of laser pulses of 10 kHz, pulse duration of 10 ns, and the energy per pulse of 2 mJ. Data from dynamic light scattering shows that ruby nanoparticles with average size of 310 nm formed after laser fragmentation. Laser-fragmented nanoparticles of ruby were incorporated into a free-standing film of fluoropolymer LF-32. This type of polymer is widely used for greenhouses coatings. Photoluminescence map of the nano-composite of fluoropolymer LF-32 with nanoparticles of ruby (Fig. 1) comprised both photoluminescence peaks of LF-32 (350-550 nm) and photoluminescence peaks of ruby in the vicinity of 700 nm. Thus, coatings based on ruby nanoparticles are a promising replacement for existing materials for greenhouse coatings.
This work was supported by a grant of the Ministry of Science and Higher Education of the Russian Federation (075-15-2022-315) for the organization and development of a world-class research center ''Photonics" and scholarship of the President of the Russian Federation for young scientists and graduate students (SP- 1006.2021.1). We thank our industrial partner Pokkels LLC for providing innovative technical solutions.
Fig. 1. Luminescence map of ruby nanoparticles in fluoropolymer matrix.
[1] S. B. Powles, Photoinhibition of Photosynthesis Induced by Visible Light, Annual review of plant physiology, vol. 35, pp. 15-44, (1984).
[2] A. V. Simakin et al., Photoconversion fluoropolymer films for the cultivation of agricultural plants under conditions of insufficient insolation, Applied Sciences, vol. 10, №22, p. 8025, (2020).
[3] S. V. Gudkov et al., Development and application of photoconversion fluoropolymer films for greenhouses located at high or polar latitudes, Journal of Photochemistry and Photobiology B: Biology, vol. 213, p. 112056, (2020).
