Fluorescence-excitation spectra of acridine orange-DNA and -RNA systems

1967 ◽  
Vol 4 (1) ◽  
pp. 23-29 ◽  
Author(s):  
Giiti Tomita
Keyword(s):  
Acridine Orange ◽  
Excitation Spectra ◽  
Fluorescence Excitation ◽  
Dna And Rna ◽  
Fluorescence Excitation Spectra

Laser-Induced Fluorescence Excitation Spectra oftert-Butoxy and 2-Butoxy Radicals

1999 ◽  
Vol 103 (41) ◽  
pp. 8207-8212 ◽  
Author(s):  
Chuji Wang ◽  
Liat G. Shemesh ◽  
Wei Deng ◽  
Michael D. Lilien ◽  
Theodore S. Dibble
Keyword(s):  
Laser Induced Fluorescence ◽  
Excitation Spectra ◽  
Fluorescence Excitation ◽  
Fluorescence Excitation Spectra

scholarly journals Single-Cell and Bulk Fluorescence Excitation Signatures of Seven Phytoplankton Species During Nitrogen Depletion and Resupply

2018 ◽  
Vol 73 (3) ◽  
pp. 304-312 ◽  
Author(s):  
Stefan T. Faulkner ◽  
Cameron M. Rekully ◽  
Eric M. Lachenmyer ◽  
Ergun Kara ◽  
Tammi L. Richardson ◽  
...  
Keyword(s):  
Single Cell ◽  
Aquatic Ecosystems ◽  
Single Cells ◽  
Vital Role ◽  
Phytoplankton Species ◽  
Nitrogen Depletion ◽  
Excitation Spectra ◽  
Fluorescence Excitation ◽  
Fluorescence Excitation Spectra ◽  
Taxonomic Groups

Phytoplankton play a vital role as primary producers in aquatic ecosystems. One common approach to classifying phytoplankton is fluorescence excitation spectroscopy, which leverages the variation in types and concentrations of pigments among different phytoplankton taxonomic groups. Here, we used a fluorescence imaging photometer to measure excitation ratios (“signatures”) of single cells and bulk cultures of seven differently pigmented phytoplankton species as they progressed from nitrogen N-replete to N-depleted conditions. Our objective was to determine whether N depletion alters the fluorescence excitation signature of each species and, if so, how quickly they recover when N (as nitrate) was resupplied, because these factors affect our ability to classify the species correctly. Of the seven species studied, only Proteomonas sulcata, a marine cryptophyte, showed measurable changes in single-cell fluorescence excitation ratios and bulk fluorescence excitation spectra. These changes were likely due to decreases in the cellular concentration of phycoerythrin, a N-rich pigment, as N became scarce. Within 3 h of resupply of N, fluorescence signatures began returning to pre-depletion values and were indistinguishable from N-replete cells by 80 h after resupply. These data suggest that our classification approach is robust for non-PE containing phytoplankton. PE-containing phytoplankton might exhibit systematic changes in their signatures depending on their level of N depletion, but this could be detected and the phytoplankton re-classified following a few hours of incubation in N replete conditions.

Photoassociation due to electron transfer. Exciplex formation in non-polar solvent

1971 ◽  
Vol 24 (9) ◽  
pp. 1797 ◽  
Author(s):  
RJ McDonald ◽  
BK Selinger
Keyword(s):  
Polar Solvent ◽  
Excitation Energy Transfer ◽  
Acceptor Pair ◽  
Excitation Spectra ◽  
Fluorescence Excitation ◽  
Exciplex Formation ◽  
Reversible Dissociation ◽  
Fluorescence Excitation Spectra ◽  
Donor Acceptor ◽  
Donor Acceptor Pair

Exciplexes may be formed by exciting either partner of a given electron donor-acceptor pair. As the formation of such exciplexes is reversible, dissociation may lead to excitation energy transfer. ��� The temperature dependence of fluorescence excitation spectra has proved to be a powerful tool for exploring these systems.

scholarly journals Plasmon enhancement of fluorescence of phthalocyanines metallocomplexes in solutions of silver nanoparticles

2019 ◽  
Vol 220 ◽  
pp. 03003
Author(s):  
Aleksandr Starukhin ◽  
Vladimir Apyari ◽  
Aleksander Gorski ◽  
Andrei Ramanenka ◽  
Aleksei Furletov
Keyword(s):  
Silver Nanoparticles ◽  
Silicon Dioxide ◽  
Binary Mixtures ◽  
Low Temperatures ◽  
Plasmonic Enhancement ◽  
Excitation Spectra ◽  
Fluorescence Excitation ◽  
Hydrophobic Compounds ◽  
Fluorescence Excitation Spectra ◽  
Plasmon Enhancement

A method of creation of aqueous solutions with silver nanoparticles for studying of fluorescence of hydrophobic compounds has been proposed for metallocomplexes of phthalocyanines. The effect of silver nanoparticles on the fluorescence of phthalocyanines metallocomplexes at room and low temperatures was studied. The addition of silver nanoparticles leads to plasmonic enhancement of signals in fluorescence and fluorescence excitation spectra of the compounds of interest from 1,5 to more than 7 times. The lifetimes and quantum yield of fluorescence were measured for solutions of metallophthalocyanines in binary mixtures and in binary mixtures with the addition of silver triangular nanoplates with shells of silicon dioxide.

Physiological Significance of Overproduced Carotenoids in Transformants of the Cyanobacterium Synechococcus PCC7942

1999 ◽  
Vol 54 (3-4) ◽  
pp. 191-198
Author(s):  
Navassard V. Karapetyan ◽  
Ute Windhövel ◽  
Alfred R. Holzwarth ◽  
Peter Böger
Keyword(s):  
Protein Complexes ◽  
Photosynthetic Apparatus ◽  
Fluorescence Emission ◽  
Fluorescence Induction ◽  
Carotenoid Content ◽  
Excitation Spectra ◽  
Fluorescence Excitation ◽  
Whole Cells ◽  
Fluorescence Excitation Spectra ◽  
Synechococcus Pcc7942

Abstract The functional location of carotenoids in the photosynthetic apparatus of -crtB and -pys transformants of the cyanobacterium Synechococcus PCC7942 was studied and compared with a control strain -pFP 1-3. These transformants overproduce carotenoids due to the insertion of an additional foreign phytoene synthase gene. A higher carotenoid content was found for -crtB and -pys transformants both in whole cells and isolated membranes; the -crtB transformant was also enriched with chlorophyll. 77-K fluorescence emission and excitation spectra of the phycobilin-free membranes were examined for a possible location of overproduced carotenoids in pigment-protein complexes in situ. A similar ratio of the amplitudes of fluorescence bands at 716 and 695 nm emitted by photosystems I and II, found for the three strains, indicates that the stoichiometry between photosystems of the transformants was not changed. Overproduced carotenoids are not located in the core antenna of photosys­ tem I, since 77-K fluorescence excitation spectra for photosystem I of isolated membranes from the studied strains do not differ in the region of carotenoid absorption. When illuminated with light of the same intensity but different quality, absorbed preferentially by either carotenoids, chlorophylls or phycobilins, respectively, oxygen evolution was found always higher in the transformants -crtB and -pys than in -pFP 1-3 control cells. Identical kinetics of fluorescence induction of all strains under carotenoid excitation did not reveal a higher activity of photosystem II in cells enriched with carotenoids. It is suggested that overproduced carotenoids of the transformants are not involved in photosynthetic light-harvesting; rather they may serve to protect the cells and its membranes against photodestruction.

scholarly journals Electronic Spectra of 1-Phenylethylamine and its Derivatives in Supersonic Jets

1990 ◽  
Vol 10 (3) ◽  
pp. 169-175
Author(s):  
Seiji Yamamoto ◽  
Taeko Niwa ◽  
Mitsuo Ito
Keyword(s):  
Relaxation Process ◽  
Electronic Spectra ◽  
Fluorescence Spectra ◽  
Phenyl Group ◽  
Nonradiative Relaxation ◽  
Excitation Spectra ◽  
Fluorescence Excitation ◽  
Fluorescence Excitation Spectra ◽  
Dispersed Fluorescence ◽  
Asymmetric Carbon

The S1←S0 fluorescence excitation spectra and dispersed fluorescence spectra of jet-cooled (+)-, (-)- and (±)-1-phenylethylamine and their derivatives (amides) have been observed. The 0-0 band of the amine locates at 37,641 cm-1. The amides which were synthesized from (+)-amine or (-)-amine with (+)-tartaric acid are diastereomers. It was found that the two diastereomers give the identical spectra with the 0-0 band at 34,757 cm-1. No difference in the spectrum indicates that the excitation is localized in the phenyl group which is far from the asymmetric carbon causing diastereoism. It was also found that 1-phenylethylamine has a fast nonradiative relaxation process in the Sstate, but such a process is removed by the formation of the amide.

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