Structure of the Red Fluorescence Band in Chloroplasts

Using Weber's method of "matrix analysis" for the estimation of the number of fluorescent species contributing to the emission of a sample, it is shown that the fluorescence1 band in spinach chloroplast fragments at room temperature originates in two species of chlorophyll a. Emission spectra obtained upon excitation with different wavelengths of light (preferentially absorbed in chlorophyll a or b) are presented. Upon cooling to - 196°C, the fluorescence efficiency increases about twentyfold. Two additional bands, that now appear at 696 and 735 mµ, suggest the participation of four molecular species. Emission spectra observed at different concentrations of chloroplast fragments with excitation in chlorophyll a and b and excitation spectra for different concentrations of chloroplast fragments and measurements at 685 and 760 mµ are presented. Two of the four emission bands may belong to pigment system I and two to system II. The 685, 696, and 738 mµ bands respond differently to temperature changes. In the -196°C to -150°C range, the intensity of the 685 mµ band remains constant, and that of the 696 mµ band decreases twice as fast as that of the 738 mµ band.

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Luminescence spectroscopy of Mn2+ rock-forming carbonates

Mineralogical Magazine ◽

10.1180/minmag.1989.053.370.07 ◽

1989 ◽

Vol 53 (370) ◽

pp. 201-211 ◽

Cited By ~ 22

Author(s):

G. Walker ◽

O. E. Abumere ◽

B. Kamaluddin

Keyword(s):

Simple Model ◽

Metal Cation ◽

Room Temperature ◽

Emission Spectra ◽

Luminescence Spectroscopy ◽

Ligand Field ◽

Absorption Profile ◽

Excitation Spectra ◽

Cation Site ◽

Ligand Field Parameters

AbstractCathodoluminescence emission spectra and luminescence excitation spectra of Mn2+ in calcites, dolomites, magnesites, a manganocalcite and a rhodochrosite have been measured at both room temperature and 77 K. Ligand-field parameters have been calculated from the excitation spectra which reflect the size of the metal cation site in which the Mn2+ ion resides. The technique of luminescence excitation spectra has enabled the absorption profile of Mn2+ in Mg and Ca sites in dolomite to be separately determined. The variation of the distribution of Mn2+ between Mg and Ca sites in dolomites is demonstrated and discussed in terms of a simple model. It is concluded that the distribution of Mn2+ in dolomites may well provide information about its conditions of formation and/or subsequent alteration.

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OPTICAL PROPERTIES OF Eu3+ IONS IN LaF3 NANOCRYSTALS

Vietnam Journal of Science and Technology ◽

10.15625/2525-2518/54/1a/11810 ◽

2018 ◽

Vol 54 (1A) ◽

pp. 88

Author(s):

Hoang Manh Ha

Keyword(s):

Optical Properties ◽

Room Temperature ◽

Emission Spectra ◽

Electric Dipole Transition ◽

Dipole Transition ◽

Radiative Properties ◽

Transition Intensity ◽

Excitation Spectra ◽

R Ratio ◽

High Degree

LaF3 nanocrystals doped with different concentrations of Eu3+ ions were synthesized by hydrothermal method. The XRD, luminescence and excitation spectra have been studied at room temperature. The ratio of the 5D0→7F2 electric dipole transition intensity to the 5D0→7F1 magnetic dipole transition intensity (R) was used to evaluate the asymmetry of Eu3+ site. Judd-Ofelt parameters were calculated from emission spectra and were used to predict the radiative properties of 5D0→7FJ transitions also the lifetime of 5D0 level. The small values of Ω2 parameter and R ratio relate to high degree of symmetry of ligand around Eu3+ site in this material.

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Luminescent Properties of As-Grown and Vacuum Annealed LiNbO3 Single Crystals

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.200.199 ◽

2013 ◽

Vol 200 ◽

pp. 199-202

Author(s):

Dmytro Yu. Sugak ◽

Andriy P. Luchechko

Keyword(s):

Single Crystals ◽

Room Temperature ◽

Emission Spectra ◽

Luminescent Properties ◽

Annealed Sample ◽

Luminescence Spectra ◽

Excitation Spectra ◽

X Ray ◽

Grown Sample ◽

Different Types

This paper reports on the luminescent properties of the congruent as-grown and vacuum annealed LiNbO3 single crystals at the UV and X-ray excitations. The shape of excitation spectra is similar for all emission bands in as-grown sample as well as in vacuum annealed sample. The emission spectra (exc=235 nm) observed in the spectral region 250…800 nm at room temperature consist of five elementary bands. Correlation of the relative intensities bands in luminescence spectra under different types of excitation and their temperature dependencies were determined. The most intensitive maxima in as-grown sample are observed at 295 and 691 nm. The main maximum after vacuum annealing is peaked around 295 nm.

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Changes of the Photosynthetic Apparatus in Spirulina Cyanobacterium by Sodium Stress

Zeitschrift für Naturforschung C ◽

10.1515/znc-2000-1-205 ◽

2000 ◽

Vol 55 (1-2) ◽

pp. 16-22 ◽

Cited By ~ 7

Author(s):

Kavita Verma ◽

Prasanna Mohanty

Keyword(s):

Chlorophyll A ◽

Photosystem I ◽

Protein Interactions ◽

Room Temperature ◽

Photosynthetic Apparatus ◽

Fluorescence Emission ◽

Emission Spectra ◽

Energy Harvest ◽

Fluorescence Emission Spectra ◽

Transfer Processes

Abstract Spirulina platensis trichomes grown in Zarrouks medium having total Na+ concentration as 0.14 ᴍ when transfered to fresh Zarrouks medium containing enhanced level of Na+ ions equal to 0.86 ᴍ showed 30% more accumulation of Na+ intracellularly as compared to the control. An inhibition of photosystem II activity to almost 66% was observed. Also due to this exposure to high Na+, the room temperature absorption characteristics of Spirulina trichomes and the thylakoid membrane preparations w ere altered indicating changes in the chromophore protein interactions and alterations in the phycocyanin/allophycocyanin ratio; there by affecting the energy harvest and energy transfer processes. An increase in the carotenoid absorption was two fold over the control in the treated sample. Similarly, room temperature and low temperature (77 K) fluorescence emission spectra collectively suggested alterations in the chlorophyll a emissions, F 726 of photosystem I reflecting changes in the lipid protein environment of the thylakoid. Our results indicate that in Spirulina the enhanced Na+ level alters the energy harvest and transfer processes. It also affected the emission characteristics of chlorophyll a of photosystem I.

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Spektren und Abklingprozessc der Mn(II)-Lumineszenz in Alkalichloriden; Untersuchung ihrer Konzentrationsabhangigkeit in MnCl2/LiCl / Spectra and Decay Processes of the Mn(II)-Luminescence in Alkali Chlorides; Investigation into their Dependence on Concentration in MnCl2LiCl

Zeitschrift für Naturforschung A ◽

10.1515/zna-1977-0511 ◽

1977 ◽

Vol 32 (5) ◽

pp. 437-444 ◽

Cited By ~ 1

Author(s):

D. Oelkrug ◽

E. Bina

Keyword(s):

Temperature Dependence ◽

Exponential Function ◽

Room Temperature ◽

Metastable Phase ◽

Emission Spectra ◽

Lattice Defects ◽

Excitation Spectra ◽

Host Lattices ◽

Alkali Chlorides ◽

New Phase

AbstractLuminescence emission spectra, excitation spectra and decay curves of manganese (II) in alka line chloride host lattices were measured at room temperature and 77 K. In most samples the decay curves deviate strongly from an exponential function. Concentration and temperature dependence of the results and a comparison with the homogeneous phases of manganese (II) compounds leads to the following conclusion: In LiCl the statistical incorporation of Mn(II) predominates strongly; an interaction dependent on concentration between Mn (II) -ions and cationic lattice defects could be detected. In NaCl, isolated and linked MnCl6-octahedra have to be considered also at very low Mn (II) -concentrations. In KCl, pairs and bigger aggregates of linked octahedra occur much more frequently than the isolated MnCl6 units. In RbCl a uniform new phase of rubidiumchloro-manganate with linked MnCl6-octahedra is formed. The situation in CsCl is quite similar to that in RbCl, but there exists an additional metastable phase with MnCl4-tetrahedra.

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Optical Spectra of Chlorophyll a and b Molecules and Complexes in PMMA and MTHF

Zeitschrift für Naturforschung A ◽

10.1515/zna-1978-1013 ◽

1978 ◽

Vol 33 (10) ◽

pp. 1197-1205

Author(s):

W. Hägele ◽

D. Schmid ◽

F. Drissler ◽

J. Nauš ◽

H. C. Wolf

Keyword(s):

Energy Transfer ◽

Chlorophyll A ◽

Fluorescence Spectra ◽

Emission Spectra ◽

Optical Spectra ◽

Chlorophyll B ◽

High Concentration ◽

Transfer Processes ◽

Wide Range ◽

Chlorophyll A And B

AbstractThe optical spectra of chlorophyll a and chlorophyll b in PMMA and MTHF were studied over a wide range of concentration (8 X 10-6-1 X 10-3 mole/l in PMMA, and 10-6-10-1 mole/l in MTHF). In the absorption spectra it is possible to identify bands which originate from chlorophyll disolvates and chlorophyll monosolvates in MTHF as well as bands which are most probably due to isolated chlorophyll molecules in PMMA. In high-concentration samples of chlorophyll in MTHF some bands may be assigned to aggregates, but based on optical results only, no particular model can be proposed. The emission spectra are strongly influenced by reabsorption and energy transfer processes. However, the so-called Qy band of isolated molecules in PMMA and of chlorophyll monosolvates in MTHF as well as the Qx and the Qy bands of chlorophyll disolvates in MTHF can be identified unequivocally in the fluorescence spectra.

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Untersuchungen an Chrom-Leuchtzentren in Magnesiumtitanat

Zeitschrift für Naturforschung A ◽

10.1515/zna-1969-0908 ◽

1969 ◽

Vol 24 (9) ◽

pp. 1323-1328

Author(s):

R. Dittmann ◽

D. Hahn ◽

J. Stade

Keyword(s):

Energy Transfer ◽

Absorption Spectra ◽

Room Temperature ◽

Emission Spectra ◽

Activator Concentration ◽

Excitation Spectra ◽

Oxygen Ions ◽

The Difference

Chromium activated powdery Mg2TiO4 was prepared using the oxides MgO and TiO2 with LiCl as a flux. The preparation was realized by two annealing processes one after another at 850 °C and 1400 °C for activated specimens and for samples without activator. The excitation spectra were measured at room temperature and 77 K. The difference in remission was investigated at 293 K for activated samples and specimens without chromium and also the difference in absorption for the same samples. The excitation-, remission- and absorption spectra show three peaks with a different behaviour if the activator concentration increases. Therefore the chromium luminescence centres in the Mg2TiO4 prove to be Cr3+-ions surrounded by six oxygen ions and chromium clusters respectively. The assumption of two different luminescence centres is supported by the results of the emission spectra. An energy transfer exists between these two types of centres and depends on the activator concentration.

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Laser Spectrofluorimetry of Chlorophylls

Canadian Journal of Chemistry ◽

10.1139/v74-556 ◽

1974 ◽

Vol 52 (22) ◽

pp. 3723-3727 ◽

Cited By ~ 21

Author(s):

Roger M. Leblanc ◽

Geneviève Galinier ◽

Alain Tessier ◽

Lise Lemieux

Keyword(s):

Chlorophyll A ◽

Emission Spectra ◽

Polarization Rotator ◽

Excitation Beam ◽

Solid States ◽

Set Up

A device has been set up to determine quantitatively the weak fluorescence intensities of pigment molecules. It consists of a laser spectrofluorimeter. The excitation beam can be produced with either a He/Cd laser (441.6 nm) or a He/Ne laser (632.8 nm). This system allows us to detect the fluorescence of dilute chlorophyll a or b solutions of the order of 10−12 mol/l. This sensitivity also permits the study of the emission spectra from chlorophyll in monomolecular or solid states, and since a polarization rotator has been incorporated into our apparatus, one may presume some possible orientation of the molecules.

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Excitation versus Emission Spectra as a Means to Examine Selective Fluorescence Quenching Agents

Applied Spectroscopy ◽

10.1366/0003702924123755 ◽

1992 ◽

Vol 46 (9) ◽

pp. 1388-1392 ◽

Cited By ~ 11

Author(s):

Sheryl A. Tucker ◽

William E. Acree

Keyword(s):

Fluorescence Quenching ◽

Spectral Data ◽

Emission Spectra ◽

Data File ◽

Excitation Spectra

To ascertain whether fluorescence quenching is best studied with the use of excitation or emission spectra, and to expand our existing PAH spectral data file, we have recorded excitation spectra of benzo[b]perylene, dibenzo[hi,wx]heptacene, tetrabenzo[de,hi,mn,qr]naphthacene, perylene, benzo[a]fluoranthene, benzo[def]indeno[1,2,3hi]chrysene, naphtho[2,1a]fluoranthene, naphtho[2,3b]fluoranthene, benzo[k]fluoranthene, 2-azapyrene, naphtho[8,1,2hij]pyreno[9,10,1def]phthalazine, indeno[1,-2,3ij]isoquinoline, benzo(lmn][3,8]phenanthroline, and 7-methyldibenzo(b,def]chrysene at various nitromethane concentrations. Results of these measurements verify our earlier observations concerning the nitromethane selective quenching rule and further illustrate the importance of considering inner-filtering artifacts in quenching studies.

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