scholarly journals Construction model for microalgae photometric cell

2021 ◽  
pp. 79-86
Author(s):  
A.S. Gulin ◽  
◽  
R.P. Trenkenshu ◽  
Keyword(s):  
Absorption Spectrum ◽  
Emission Spectrum ◽  
Absorption Spectra ◽  
Red Light ◽  
Wavelength Region ◽  
High Sensitivity ◽  
Transmitted Light ◽  
Chlorophyll B ◽  
Light Spectrum ◽  
Speed Accuracy

The work assesses the efficiency of red light-emitting diodes widely used in phyto-irradiators. The article focuses on the emitting monochrome LED with an extended radiation range in a photometric cell used for determining the concentration of pigments in microalgae cultures, Spectrophotometric methods are known as the most accurate and relevant methods for assessing the concentration of pigments, having significant advantages for monitoring and controlling the process over chemical ones in terms of selectivity, speed, accuracy, sensitivity, substance consumption, as well as the possibility of continuous analysis in a flow. The study of the emission spectra of red LEDs, their comparison with the absorption spectra of microalgae cultures, as well as the selection of the most accessible emitting element for the photometric cell is carried out. The analysis of the absorption spectra of the culture and extracts of Dunaliella salina using the method of dividing the long-wavelength region of the spectrum (from 600 to 700 nm) into separate Gaussian curves is presented. Based on the results obtained, the choice of an LED is made, which has an extended radiation range and allows providing a high sensitivity of the device, with low price making it easy to manufacture a photometric cell. Comparison between the emission spectrum of the LED and the absorption spectrum of the microalgae culture allows us to conclude that the emission spectrum of the LED emitter is in good agreement with the maximum absorption spectrum of the chlorophyll b pigment in the 620–700 nm region, which means that such an emitter is capable of providing a higher energy efficiency. The spectrum of the transmitted light entering the photodetector is also built. It is concluded that the proposed LED, when used in a photometric cell, can effectively work with pigments in the red region of the spectrum. The obtained device spectra allow determining such culture characteristics as biomass and the ratio of chlorophyll a and chlorophyll b. The transmitted light spectrum allows determining not only the average value of the energy received by the photocell but also the amount of pigments.

scholarly journals Strongly enhanced luminescence of Sr4Al14O25:Mn4+phosphor by co-doping B3+and Na+ions with red emission for plant growth LEDs

RSC Advances ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 1469-1476 ◽  
Author(s):  
Jiaqi Long ◽  
Xuanyi Yuan ◽  
Chaoyang Ma ◽  
Miaomiao Du ◽  
Xiaoli Ma ◽  
...  
Keyword(s):  
Absorption Spectrum ◽  
Plant Growth ◽  
Emission Spectrum ◽  
Chlorophyll B ◽  
Red Phosphor ◽  
Red Emission ◽  
Co Doping ◽  
Na Ions ◽  
Enhanced Luminescence ◽  
Blue Chip

(a) Emission spectrum of LEDs fabricated with 445 nm blue chip and Sr2Si5N8:Eu2+red phosphor. (b) Emission spectrum of LEDs fabricated with 445 nm blue chip and Sr4Al14O25:Mn4+phosphor. (c and d) Absorption spectrum of chlorophyll-b and chlorophyll-a.

n–π* Electronic Emission and Absorption Spectra of o-Fluorobenzaldehyde in Vapor Phase

1970 ◽  
Vol 24 (1) ◽  
pp. 36-41 ◽  
Author(s):  
M. P. Srivastava ◽  
I. S. Singh
Keyword(s):  
Absorption Spectrum ◽  
Excited State ◽  
Emission Spectrum ◽  
Absorption Spectra ◽  
Vapor Phase ◽  
Ground State ◽  
Emission And Absorption Spectra ◽  
Quartz Spectrograph

The electronic emission and absorption spectra of o-fluorobenzaldehyde have been studied. The emission spectrum recorded on a Fuess glass and a medium quartz spectrograph lies in the region 26 668–17 862 cm−1 and the absorption spectrum recorded on a Zeiss Q–24 medium quartz spectrograph lies in the region 30 995–24 610 cm−1. The O—O band has been observed at 26 337 cm−1. The C=O stretching frequency 1733 cm−1 in the ground state and 1355 cm−1 in the excited state is most intense and forms progressions of bands both in the emission and absorption spectra. The observed bands have been interpreted as combinations of the C=O stretching frequency and its multiples with other fundamentals. The transition involved is A‘–A’ ( n–π*).

scholarly journals Absorption Spectrum of Atomic Chlorine 95.0 nm to 61.0 nm

1987 ◽  
Vol 120 ◽  
pp. 93-94
Author(s):  
W. H. Parkinson ◽  
A.M. Cantú
Keyword(s):  
Experimental Study ◽  
Absorption Spectrum ◽  
Absorption Spectra ◽  
Cross Sections ◽  
Ground State ◽  
Wavelength Region ◽  
Normal Incidence ◽  
Flash Pyrolysis ◽  
Atomic Chlorine

The experimental study of atomic chlorine absorption spectra using a flash-pyrolysis system and a 2-m normal incidence spectrograph in the wavelength region 95 nm to 61 nm has produced photoabsorption cross sections, wavelength measurements, and line series identification involving the 3P, 1D and 1S limits. Absorption spectra originating from both levels ( and ) of the ground state have been produced by this method.

Magnetic plasmons induced in a dielectric-metal heterostructure by optical magnetism

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Shulei Li ◽  
Lidan Zhou ◽  
Mingcheng Panmai ◽  
Jin Xiang ◽  
Sheng Lan
Keyword(s):  
Transverse Electric ◽  
Incidence Angle ◽  
High Sensitivity ◽  
Critical Value ◽  
Transverse Magnetic ◽  
Quality Factors ◽  
Light Spectrum ◽  
Optical Resonances ◽  
Scattering Spectra ◽  
Plasmon Polaritons

Abstract We investigate numerically and experimentally the optical properties of the transverse electric (TE) waves supported by a dielectric-metal heterostructure. They are considered as the counterparts of the surface plasmon polaritons (i.e., the transverse magnetic (TM) waves) which have been extensively studied in the last several decades. We show that TE waves with resonant wavelengths in the visible light spectrum can be excited in a dielectric-metal heterostructure when the optical thickness of the dielectric layer exceeds a critical value. We reveal that the electric and magnetic field distributions for the TE waves are spatially separated, leading to higher quality factors or narrow linewidths as compared with the TM waves. We calculate the thickness, refractive index and incidence angle dispersion relations for the TE waves supported by a dielectric-metal heterostructure. In experiments, we observe optical resonances with linewidths as narrow as ∼10 nm in the reflection or scattering spectra of the TE waves excited in a Si3N4/Ag heterostructure. Finally, we demonstrate the applications of the lowest-order TE wave excited in a Si3N4/Ag heterostructure in optical display with good chromaticity and optical sensing with high sensitivity.

scholarly journals The Preferences of Different Cultivars of Lettuce Seedlings (Lactuca sativa L.) for the Spectral Composition of Light

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1211
Author(s):  
Barbara Frąszczak ◽  
Monika Kula-Maximenko
Keyword(s):  
Chlorophyll Content ◽  
Blue Light ◽  
White Light ◽  
Leaf Shape ◽  
Red Light ◽  
Spectral Composition ◽  
Fresh Weight ◽  
Light Spectrum ◽  
Dark Green ◽  
Relative Chlorophyll Content

The spectrum of light significantly influences the growth of plants cultivated in closed systems. Five lettuce cultivars with different leaf colours were grown under white light (W, 170 μmol m−2 s−1) and under white light with the addition of red (W + R) or blue light (W + B) (230 μmol m−2 s−1). The plants were grown until they reached the seedling phase (30 days). Each cultivar reacted differently to the light spectrum applied. The red-leaved cultivar exhibited the strongest plasticity in response to the spectrum. The blue light stimulated the growth of the leaf surface in all the plants. The red light negatively influenced the length of leaves in the cultivars, but it positively affected their number in red and dark-green lettuce. It also increased the relative chlorophyll content and fresh weight gain in the cultivars containing anthocyanins. When the cultivars were grown under white light, they had longer leaves and higher value of the leaf shape index. The light-green cultivars had a greater fresh weight. Both the addition of blue and red light significantly increased the relative chlorophyll content in the dark-green cultivar. The spectrum enhanced with blue light had positive influence on most of the parameters under analysis in butter lettuce cultivars. These cultivars were also characterised by the highest absorbance of blue light.

The Preparation and Photocatalytic Activity of SWNTs Doped ZnO/TiO2 Compound Films

2010 ◽  
Vol 97-101 ◽  
pp. 1611-1615 ◽  
Author(s):  
Qing Wang ◽  
Xin Li Li ◽  
Wei Nie ◽  
Yong Mei Xia ◽  
Jian Feng Dai
Keyword(s):  
Photocatalytic Activity ◽  
Absorption Spectra ◽  
Sol Gel ◽  
Composite Films ◽  
Wavelength Region ◽  
Tio2 Films ◽  
X Ray Diffraction ◽  
Sol Gel Process ◽  
Doped Zno ◽  
Walled Carbon Nanotubes

The ZnO/TiO2 composite films were deposited over glass using spin coating technique by sol-gel process. Single-walled carbon nanotubes (SWNTs) were used to modify the ZnO/TiO2 films successfully in this paper. The structure and composition of the ZnO/TiO2 composite and SWNTs doped ZnO/TiO2 composite were characterized by X-ray diffraction (XRD). The morphology of samples was characterized by scanning electron microscopy (SEM). The photocatalytic activity was investigated by photocatalytic degradation of aqueous methyl orange under ultraviolet (UV) radiation. The UV-vis absorption spectra of the ZnO/TiO2 films and SWNTs doped ZnO/TiO2 films in the wavelength region 200~800 nm were obtained. The results indicate that the SWNTs addition can decrease the grain size of ZnO/TiO2, which can enhance the photocatalytic activity. UV-vis absorption spectra of SWNTs-ZnO/TiO2 showed obvious blue shifts compared with ZnO/TiO2. The optimal amount of doping SWNTs is 1% according to this research. The enhanced mechanism of the SWNTs for the photocatalytic activity in ZnO/TiO2 films was analyzed in this article.

scholarly journals Photocatalytic Activity and Characterization of Carbon-Modified Titania for Visible-Light-Active Photodegradation of Nitrogen Oxides

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Chun-Hung Huang ◽  
Yu-Ming Lin ◽  
I-Kai Wang ◽  
Chun-Mei Lu
Keyword(s):  
Visible Light ◽  
Carbon Number ◽  
Red Light ◽  
Matrix Material ◽  
Carbon Sources ◽  
Impregnation Method ◽  
Light Spectrum ◽  
Precursor Molecule ◽  
Visible Light Active ◽  
Carbonate Species

A variety of carbon-modified titania powders were prepared by impregnation method using a commercial available titania powder, Hombikat UV100, as matrix material while a range of alcohols from propanol to hexanol were used as precursors of carbon sources. Rising the carbon number of alcoholic precursor molecule, the modified titania showed increasing visible activities ofNOxphotodegradation. The catalyst modified with cyclohexanol exhibited the best activities of 62%, 62%, 59%, and 54% for the totalNOxremoval under UV, blue, green, and red light irradiation, respectively. The high activity with long wavelength irradiation suggested a good capability of photocatalysis in full visible light spectrum. Analysis of UV-visible spectrum indicated that carbon modification promoted visible light absorption and red shift in band gap. XPS spectroscopic analysis identified the existence of carbonate species (C=O), which increased with the increasing carbon number of precursor molecule. Photoluminescence spectra demonstrated that the carbonate species suppressed the recombination rate of electron-hole pair. As a result, a mechanism of visible-light-active photocatalyst was proposed according to the formation of carbonate species on carbon-modified TiO2.

A fluorescence enhancement assay of cell fusion

1977 ◽  
Vol 28 (1) ◽  
pp. 167-177
Author(s):  
P.M. Keller ◽  
S. Person ◽  
W. Snipes
Keyword(s):  
Absorption Spectrum ◽  
Energy Transfer ◽  
Emission Spectrum ◽  
Cell Fusion ◽  
Saturated Hydrocarbon ◽  
Photon Emission ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Hydrocarbon Chains ◽  
Fluorescent Molecules

Two probes were synthesized which consist of fluorescent molecules conjugated to saturated hydrocarbon chains, 18 carbons long, to ensure their localization into cellular membranes. There is an overlap between the emission spectrum of one probe (donor) and the absorption spectrum of the other probe (acceptor). By the use of appropriate wavelengths it is possible to specifically excite the donor probe and record the fluorescence of the acceptor probe. Two cell populations, each labelled with one of the probes, were infected with a virus that causes cell fusion, mixed in equal proportions, and the fluorescence of the acceptor probe measured as a function of time after infection. An increase in fluorescence was observed beginning at the time of onset of cell fusion indicating a mixing of the fluorescent membrane molecules. An investigation of the distance dependence indicated that the increase in fluorescence was mainly due to resonance energy transfer and not to photon emission and reabsorption. Resonance energy transfer requires that the 2 probes be close together and that there be an overlap of the emission spectrum of the donor probe and the absorption spectrum of the acceptor probe. The possible application of this assay to other types of membrane fusion is noted.

X-Ray Absorption Fine Structure Study in FeTiO3

1997 ◽  
Vol 11 (16n17) ◽  
pp. 745-748 ◽  
Author(s):  
Rebekah Min-Fang Hsu ◽  
Kai-Jan Lin ◽  
Cheng Tien ◽  
Lin-Yan Jang
Keyword(s):  
Absorption Spectrum ◽  
Fine Structure ◽  
Absorption Spectra ◽  
Mixed Valence ◽  
Structure Study ◽  
X Ray ◽  
Xafs Spectroscopy ◽  
Absorption Fine ◽  
Trivalent State ◽  
X Ray Absorption

X-ray absorption fine structure XAFS spectroscopy has been used to determine the valence system for the Fe atom in ilmenite, FeTiO3 . This is the first XAFS data in FeTiO3 to our knowledge. The α- Fe2O3 data served as the standard in determining the ionization of the Fe atom in FeTiO3 . Observation of intensity and k-space are consistent. There was no evidence of mixed valence on comparing the FeTiO3 near edge X-ray absorption spectrum with α- Fe2O3 data. The absorption spectra suggest that iron is in the trivalent state in ilmenite.

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