Absorption and emission spectroscopic characterization of blue-light receptor Slr1694 from Synechocystis sp. PCC6803

The BLUF protein Slr1694 from the cyanobacterium Synechocystis sp. PCC6803 is characterized by absorption and emission spectroscopy. Slr1694 expressed from E. coli which non-covalently binds FAD, FMN, and riboflavin (called Slr1694(I)), and reconstituted Slr1694 which dominantly contains FAD (called Slr1694(II)) are investigated. The receptor conformation of Slr1694 (dark adapted form Slr1694(r)) is transformed to the putative signalling state (light adapted form Slr1694(s)) with red-shifted absorption and decreased fluorescence efficiency by blue-light excitation. In the dark at 22 degrees C, the signalling state recovers back to the initial receptor state with a time constants of about 14.2s for Slr1694(I) and 17s for Slr1694(II). Quantum yields of signalling state formation of approximately 0.63+/-0.07 for both Slr1694(I) and Slr1694(II) were determined by transient transmission measurements and intensity dependent steady-state transmission measurements. Extended blue-light excitation causes some bound flavin conversion to the hydroquinone form and some photo-degradation, both with low quantum efficiency. The flavin-hydroquinone re-oxidizes slowly back (time constant 5-9 min) to the initial flavoquinone form in the dark. A photo-cycle dynamics scheme is presented.     

Macromolecular crowding effects on reactions of TePixD (Tll0078)

To reveal macromolecular crowding effects on a chemical reaction of a BLUF (sensors of blue light using FAD) protein (PixD from a thermophilic cyanobacterium Thermosynechococcus elongatus BP-1 [TePixD, Tll0078]), the photoreaction was studied at various concentrations of the macromolecule Ficoll-70 by UV/Vis absorption spectroscopy and the pulsed laser-induced transient grating (TG) method. The absorption spectrum did not change with varying concentration of Ficoll-70. The crowding did not affect the quantum yield of the spectral red shift reaction, recovery rate of the product, rate constant of the volume change reaction and the magnitude of the volume change. However, the magnitude of the TG signal representing the diffusion-sensitive conformation change significantly increased on addition of Ficoll-70. This dependence was attributed to the crowding effect on the TePixD decamer-pentamer equilibrium in the solution. This result indicates that the TePixD reaction is more efficient in cellular than in in vitro conditions.     

QUALITATIVE STUDIES OF THE LOW TEMPERATURE PHOTOCHEMISTRY OF RHODOPSIN AND RELATED PIGMENTS

Abstract— Rhodopsin, the isomeric pigments formed from 9- cis - and 9, 13- dicis -retinal, and the synthetic pigments formed from 9- cis - and 11- cis -14-methylretinal were irradiated with 490 nm light at -196C. Absorption spectral changes indicate that a distinguishable bathorhodopsin type intermediate may be formed for each pigment. The bathorhodopsin intermediates of the 9- cis pigments have band maxima hypsochromically shifted by4–5 nm compared to their corresponding rhodopsins. The bathorhodopsin type intermediate formed upon irradiation of 9, 13- dicis -rhodopsin has an absorption that maximizes 6 nm shorter than that of rhodopsin. Band maxima of the bathorhodopsin intermediates of the 14-methylrhodopsins are bathochromatically shifted ca. 8 nm compared to their corresponding rhodopsins.     

Optical characterization of Sm3+ and Dy3+:ZnO-PbO-B2O3 glasses

Here, we present the results of the analysis of Sm(3+) or Dy(3+) (0.5 mol%) ions doped heavy metal oxide (HMO)-based zinc lead borate (ZLB) glasses. Optical measurements such as absorption, emission spectra, lifetimes, XRD, DSC profiles have been carried out. The emission spectrum of Sm(3+):ZLB has shown the emission transitions of (4)G(5/2)-->(6)H(5/2) (563 nm), (4)G(5/2)-->(6)H(7/2) (598 nm), (4)G(5/2)-->(6)H(9/2) (646 nm), (4)G(5/2)-->(6)H(11/2) (708 nm) with lambda(exc): 401 nm ((6)H(5/2)-->(4)F(7/2)). In the case of the Dy(3+):ZLB glass, emission transitions of (4)F(9/2)-->(6)H(15/2) (485 nm), (4)F(9/2)-->(6)H(13/2) (575 nm) and (4)F(9/2)-->(6)H(11/2) (664 nm) with lambda(exi): 447 nm ((6)H(15/2)-->(4)I(15/2)) have been identified. Energy level schemes relating to the emission mechanisms involved in Sm(3+) and Dy(3+) glasses have been given.     

Enhancement of luminescence properties in Er3+ doped TeO2-Na2O-PbX (X=O and F) ternary glasses

An enhancement of luminescence properties in Er3+ doped ternary glasses is observed on the addition of PbO/PbF2. The infrared to visible upconversion emission bands are observed at 410, 525, 550 and 658 nm, due to the 2H9/2-->4I15/2, 2H11/2-->4I15/2, 4S3/2-->4I15/2, 4F9/2-->4I15/2 transitions respectively, on excitation with 797 nm laser line. A detailed study reveals that the 2H9/2-->4I15/2 transition arises due to three step upconversion process while other transitions arise due to two step absorption. On excitation with 532 nm radiation, ultraviolet and violet upconversion bands centered at 380, 404, 410 and 475 nm wavelengths are observed along with one photon luminescence bands at 525, 550, 658 and 843 nm wavelengths. These bands are found due to the 4G11/2-->4I15/2, 2P3/2-->4I13/2, 2H9/2-->4I15/2, 2P3/2-->4I11/2, 2H11/2-->4I15/2, 4S3/2-->4I15/2, 4F9/2-->4I15/2 and 4S3/2-->4I13/2 transitions, respectively. Though incorporation of PbO and PbF2 both enhances fluorescence intensities however, PbF2 content has an important influence on upconversion luminescence emission. The incorporation of PbF2 enhances the red emission (658 nm) intensity by 1.5 times and the violet emission (410 nm) intensity by 2.0 times. A concentration dependence study of fluorescence reveals the rapid increase in the red (4F9/2-->4I15/2) emission intensity relative to the green (4S3/2-->4I15/2) emission with increase in the Er3+ ion concentration. This behaviour has been explained in terms of an energy transfer by relaxation between excited ions.     

Study of upconversion fluorescence property of novel Er3+/Yb3+ co-doped tellurite glasses

Er3+/Yb3+ co-doped TeO2-B2O3-Nb2O5-ZnO (TBN) glasses were prepared. The absorption spectra and upconversion luminescence spectra of TBN glasses were measured and analyzed. The upconversion emission bands centered at 530, 546 and 658 nm were observed under the excitation at 975 nm, corresponding to the transitions of 2H11/2-->4I15/2, 4S3/2-->4I15/2 and 4F9/2-->4I15/2 respectively. The ratio of red emission to green emission increases with an increasing of Yb3+ ions concentration. According to the quadratic dependence on excitation power, the possible upconversion mechanisms and processes were discussed.     

Thermal stability, Judd-Ofelt theory analysis and spectroscopic properties of a new Er3+/Yb3+-codoped germano-tellurite glass

The Er3+/Yb3+-codoped 70TeO2-5Li2O-10B2O3-15GeO2 glass was prepared. The thermal stability, absorption spectra, emission spectra and up-conversion spectra were measured and investigated. The Judd-Ofelt analysis based on absorption spectra was performed in order to determine the Judd-Ofelt intensity parameters Omega(t) (t = 2, 4, 6), spontaneous emission probability, radiative lifetime and branching ratios of several Er3+ transitions. It was found that this studied glass has good thermal stability, broad fluorescence full width at half maximum (FWHM), large stimulated emission cross-section and strong up-conversion emissions at about 532, 546 and 659 nm, corresponding to the 2H(11/2)-->4I(15/2), 4S(3/2)-->4I(15/2) and 4F(9/2)-->4I(15/2) transitions of Er3+, respectively under the excitation at 970 nm. The results suggest that this Er3+/Yb3+-codoped germano-tellurite glass may be a potentially useful material for developing potential amplifiers and up-conversion optical devices.     

LOW-TEMPERATURE TRAPPING OF EARLY PHOTOINTERMEDIATES OF α-ISORHODOPSIN

Abstract— a-Isorhodopsin, an artificial visual pigment with a 9- cis -4,5-dehydro-5,6-dihydro(a)retinal chromophore, was photolyzed at low temperatures and absorption difference spectra were collected as the sample was warmed. A bathorhodopsin (Batho)-like intermediate absorbing at ca 495 nm was detected below 55 K, a blue-shifted intermediate (BSI)-like intermediate absorbing at ca 453 nm was observed when the temperature was raised to 60 K and a lumirhodopsin (Lumi)-like intermediate absorbing at ca 470 nm was found when the sample was warmed to 115 K. Photointermediates from this pigment were compared to those of native rhodopsin and 5,6-dihydroisorhodopsin. As in native rho-dopsin, Batho is the first intermediate detected in a-isorhodopsin, though unlike native rhodopsin at low temperatures BSI is observed prior to Lumi formation. a-Isorhodopsin behaves similarly to 5,6-dihydroisorhodopsin, with the same early intermediates observed in both artificial visual pigments lacking the C₅-C₆ double bond. The transition temperature for BSI formation is higher in a-isorhodopsin, suggesting an interaction involving the chromophore ring in BSI formation. The transition temperature for Lumi formation is similar for these two pigments as well as for native rhodopsin, suggesting comparable changes in the protein environment in that transition.     

Inter- and intraconfigurational transitions of Nd3+ in hexafluoroelpasolite lattices

Excitation of the 4f3 ion Nd3+ in hexafluoroelpasolite lattices by synchrotron radiation of wavelength approximately 185 nm leads to fast 4f(2)5d --> 4f3 emission below 52,630 cm(-1) and slower 4f3 --> 4f3 emission from the luminescent states (4)F(3/2) gamma8u (11 524 cm(-1)) and 2G2(9/2) gamma8u (approximately 47,500 cm(-1)). The near-infrared emission is well-resolved, and a clear interpretation of the 4I(9/2) crystal field levels and of the one-phonon vibronic sideband is given. The excitation spectrum of the 2G2(9/2) emission enables clarification of the structure of the 4f(2)5d configuration (which extends from approximately 52,000 to 128,000 cm(-1)). Detailed energy level and intensity calculations have been performed, which provide simulations of the d-f emission and the f-d excitation spectra in good agreement with experiment. It is interesting that although the 4f3 2G2(9/2) gamma8u --> 4f3 4I(J) transitions are very weak in intensity compared with transitions terminating upon higher multiplet terms, most of the 4f(2)5d (3H) 4I(9/2) gamma8g --> 4f3 emission intensity resides in the transitions to 4I(J).     

Electronic spectra and crystal field analysis of energy levels of Ho3+ in HoF6(3-)

The electronic absorption spectra of single crystals of Cs(2)NaHoF(6) have been recorded in the spectral region between 4700 and 42000 cm(-1) at temperatures down to 10 K. The structure in the (5)I(8) → (5)I(J) (J = 7-4), (5)F(J) (J = 5-1), (5)S(2), (5)G(J) (J = 4-6), (3)K(J) (J = 7, 8) transitions has been analyzed and assigned. The emission spectra (5)S(2) → (5)I(J) (J = 6-8) and (5)G(4) → (5)I(J) (J = 5-7), (5)F(5) have also been recorded at 10 K for crystals of Cs(2)NaHoF(6) and partly also for samples of Cs(2)NaHoF(6):Yb(3+). The spectra comprise magnetic dipole zero phonon lines and electric dipole allowed one-phonon vibronic sidebands. From the detailed interpretation of the emission and absorption spectra, aided by a clear understanding of the vibrational behavior of the HoF(6)(3-) moiety and by magnetic dipole intensity calculations, a data set of 59 energy levels spanning 17 multiplet terms was derived. Crystal field calculations were then performed using a 4f(10) basis, as well as including the configuration interaction with a p-electron configuration. The latter calculation, which employed 14 parameters, gave better agreement with experiment and the mean deviation was 13.5 cm(-1). A comparison with the energy level fittings for Cs(2)NaHoCl(6) has been included. The crystal field parameters for the fluoro- and chloro-systems followed empirically predicted ratios.     

Direct observation of adduct formation of alkyl and aromatic iodides with cl atoms using cavity ring-down spectroscopy

The reactions of Cl atoms with RI (R = n-C3H7, n-C4H9, cyclo-C6H11, C6H5, C6F5, and p-CH3C6H4) have been studied using cavity ring-down spectroscopy at a temperature range of 233-313 K and at 100 Torr total pressure of N2 diluent. Visible absorption spectra of the RI-Cl adducts were recorded at 440-520 nm at 263 K. The yields of the adducts were temperature-dependent. There was no discernible reaction of the adducts in the presence of 100 Torr of O2 at 263 K. Theoretical calculations were performed for C4H9I-Cl and C6H5I-Cl for quantitative explanation of the absorption spectra and the strength of the I-Cl bonds in the charge-transfer complexes. Evidence for the adduct formation following the reaction of Cl with C6H5Br was sought but not found at 440 and 520 nm.     

Fluorescence properties of Nd3+-doped tellurite glasses

The compositional and concentration dependence of luminescence of the (4)F(3/2)-->(4)I(J) (J=13/2, 11/2 and 9/2) transitions in four Nd(3+)-doped tellurite based glasses has been studied. The free-ion energy levels obtained for 60TeO(2)+39ZnO(2)+1.0Nd(2)O(3) (TZN10) glass have been analysed using the free-ion Hamiltonian model and compared with similar results obtained for Nd(3+):glass systems. The absorption spectrum of TZN10 glass has been analysed using the Judd-Ofelt theory. Relatively longer decay rates have been obtained for Nd(3+)-doped phosphotellurite glasses. The emission characteristics of the (4)F(3/2)-->(4)I(11/2) transition, of the Nd(3+):TZN10 glass, are found to be comparable to those obtained for Nd(3+):phosphate laser glasses. The non-exponential shape of the emission decay curves for the (4)F(3/2)-->(4)I(11/2) transition is attributed to the presence of energy transfer processes between the Nd(3+) ions.     

Host dependent frequency upconversion of Er3+/Yb3+-codoped bismuth-germanate glasses

The absorption and upconversion fluorescence spectra of a series of Er3+/Yb3+-codoped xBi(2)O(3)-(90-x)GeO2-10Na(2)O (BGN x, x=31, 36, 41, 46 and 51 mol%) glasses have been studied. Intense green and red emission bands at around 533, 548 and 659 nm, corresponding to the 2H(11/2)-->4I(15/2), 4S(3/2)-->4I(15/2) and 4F(9/2)-->4I(15/2) transitions of Er3+, respectively, were simultaneously observed at room temperature. The dependence of intensities of upconversion emission on excitation power and possible upconversion mechanisms were evaluated and analyzed. The important role of Bi(2)O(3) in upconversion intensity is observed and its influence on the green (533 and 548 nm) and red (659 nm) emissions is compared and discussed. The influence of Bi(2)O(3) on the upconversion emissions has been investigated based on the IR spectra.     

The gas phase tropospheric removal of fluoroaldehydes (CxF2x+1CHO, x = 3, 4, 6)

The rate coefficient of the OH reaction with the perfluoroaldehydes C(3)F(7)CHO and C(4)F(9)CHO have been determined in the temperature range 252-373 K using the pulsed laser photolysis-laser induced fluorescence (PLP-LIF) method: k(C(3)F(7)CHO+OH) = (2.0 +/- 0.6) x 10(-12) exp[-(369 +/- 90)/T] and k(C(4)F(9)CHO+OH) = (2.0 +/- 0.5) x 10(-12) exp[-(356 +/- 70)/T] cm(3) molecule(-1) s(-1), corresponding to (5.8 +/- 0.6) x 10(-13) and (6.1 +/- 0.5) x 10(-13) cm(3) molecule(-1) s(-1), respectively, at 298 K. The UV absorption cross sections of these two aldehydes and CF(3)(CF(2))(5)CH(2)CHO have been measured over the range 230-390 nm at 298 K and also at 328 K for CF(3)(CF(2))(5)CH(2)CHO. The obtained results for C(3)F(7)CHO and C(4)F(9)CHO are in good agreement with two recent determinations but the maximum value of the absorption cross section for CF(3)(CF(2))(5)CH(2)CHO is over a factor of two lower than the single one recently published. The photolysis rates of C(3)F(7)CHO, C(4)F(9)CHO and CF(3)(CF(2))(5)CHO have been measured under sunlight conditions in the EUPHORE simulation chamber in Valencia (Spain) at the beginning of June. The photolysis rates were, respectively, J(obs) = (1.3 +/- 0.6) x 10(-5), (1.9 +/- 0.8) x 10(-5) and (0.6 +/- 0.3) x 10(-5) s(-1). From the J(obs) measurements and calculated photolysis rate J(calc), assuming a quantum yield of unity across the atmospheric range of absorption of the aldehydes, quantum yields J(obs)/J(calc) = (0.023 +/- 0.012), (0.029 +/- 0.015) and (0.046 +/- 0.028) were derived for the photodissociation of C(3)F(7)CHO, C(4)F(9)CHO and CF(3)(CF(2))(5)CHO, respectively. The atmospheric implication of the data obtained in this work is discussed. The main conclusion is that the major atmospheric removal pathway for fluoroaldehydes will be photolysis, which under low NO(x) conditions, may be a source of fluorinated carboxylic acids in the troposphere.     

Study of luminescence properties of novel Er3+ single-doped and Er3+/Yb3+ co-doped tellurite glasses

The novel Er(3+) single-doped and Er(3+)/Yb(3+) co-doped tellurite glasses were prepared. The effect of Yb(2)O(3) concentration on absorption spectra, emission spectra and upconversion spectra of glasses were measured and investigated. The emission intensity, fluorescence full width at half maximum (FWHM) and upconversion luminescence of Er(3+) go up with the increasing concentration of Yb(3+) ions. The maximum FWHM of (4)I(13/2) --> (4)I(15/2) transition of Er(3+) is approximate 77 nm for 1.41 x 10(21)ions/cm(3) concentration of Yb(3+)-doped glass. The visible upconversion emissions at about 532, 546 and 659 nm, corresponding to the (2)H(11/2) --> (4)I(15/2), (4)S(3/2) --> (4)I(15/2) and (4)F(9/2) --> (4)I(15/2) transitions of Er(3+), respectively, were simultaneously observed under the excitation at 970 nm. Subsequently, the possible upconversion mechanisms and important role of Yb(3+) on the green and red emissions were discussed and compared. The results demonstrate that this kind of tellurite glass may be a potentially useful material for developing potential amplifiers and upconversion optical devices.     

Cooperative energy transfer frequency upconversion in Tb3+/Yb3+-codoped oxyfluoride glasses

In this report, we investigate the cooperative energy transfer frequency upconversion in Tb3+/Yb3+-codoped SiO2-Al(2)O(3)-Na2O-ZnF(2) oxyfluoride glasses under 980 nm diode laser excitation. The influence of both Tb3+ and Yb3+ concentration on the emission bands were investigated. With a lower Tb3+ concentration, the emission bands around 381, 416 and 438 nm, and 489, 545, 587 and 623 nm associated with (5)D(3), (5)G(6)-->(7)F(J) (J=6, 5, 4) and (5)D(4)-->(7)F(J) (J=6, 5, 4, 3) transitions were observed. However, only (5)D(4)-->(7)F(J) (J=6, 5, 4, 3) transitions appear in a higher Tb3+ concentration. The integrated upconversion luminescence intensity was examined when the temperature of sample was varied from 40 to 450 K. The dependence of the upconversion emission intensity upon the excitation power was also examined, and the upconversion mechanisms were discussed.     

Study of benzylperoxy radical using laser photolysis: ultraviolet spectrum, self-reaction, and reaction with HO2 kinetics

The ultraviolet absorption spectrum of benzylperoxy radical and the kinetics of the reactions 2C(6)H(5)CH(2)O(2) --> products (I) and C(6)H(5)CH(2)O(2) + HO(2) --> products (II) are studied. Experiments are carried out using the laser photolysis technique with time-resolved UV-visible absorption spectroscopy over the temperature range 298-353 K and the pressure range 50-200 Torr. The UV spectrum is determined relative to the known cross section of the ethylperoxy radical C(2)H(5)O(2) at 250 nm. Using factor analysis, the spectrum obtained is refined and the concentrations of the main absorbing species are extracted. The kinetic parameters are determined by analyzing and simulating the temporal profiles of the species concentrations and the experimental optical densities in the spectral region 220-280 nm. These are obtained using the recent UV spectra of the absorbing species existing in our mechanism. The Arrhenius expressions for reactions I and II are (cm(3).molecule(-1).s(-1)) k(I) = 2.50 x 10(-14)e(1562/)(T) and k(II) = 5.70 x 10(-14)e(1649/)(T). Our results are discussed and compared to literature data.     

Low-energy electron attachment to SF6. II. Temperature and pressure dependences of dissociative attachment

Low-energy electron-molecule collisions, leading to dissociative attachment through metastable anionic states, are kinetically modeled within the framework of statistical unimolecular rate theory. The reaction e(-)+SF(6)-->SF(5)(-)+F is used as an illustrative example. The modeling is applied to new measurements of branching fractions for SF(5)(-) formation in the bath gas He between 360 and 670 K at 1 and 2 Torr, and between 490 and 620 K over the range of 0.3-9 Torr. The analysis of the data follows the previous kinetic modeling of the nondissociative electron attachment, e(-)+SF(6)-->SF(6)(-), from Part I of this series. Experimental results from the present work and the literature on branching fractions and total cross sections for anion formation as functions of electron energies, bath gas temperatures and pressures, as well as observation times are analyzed. The assumption of a participation of the electronic ground state of SF(6)(-) alone suffices to model the available experimental data. A value of the dissociation energy of SF(6)(-) into SF(5)(-)+F of E(0,dis)=1.61(+/-0.05) eV is determined, which may be compared to the electron affinity of SF(6), EA=1.20(+/-0.05) eV, such as derived in Part III of this series.     

Up-conversion luminescence analysis in ytterbium-sensitized erbium-doped oxide-halide tellurite and germanate-niobic-lead glasses

Ytterbium-sensitized erbium-doped oxide-halide tellurite and germanate-niobic-lead glasses have been synthesized by conventional melting method. Intense green and red emissions centered at 525, 546 and 657 nm, corresponding to the transitions 2H11/2-->4I15/2, 4S3/2-->4I15/2 and 4F9/2-->4I15/2, respectively, were simultaneously observed at room temperature in these glasses. The quadratic dependence of the 525, 546 and 657 nm emissions on excitation power indicates that a two-photon absorption process occurs. Tellurite glass showed a weaker up-conversion emission than germanate-niobic-lead glass, which is inconsistent with the prediction from the difference of maximum phonon energy between tellurite and germanate-niobic-lead glasses. In this paper, Raman spectroscopy was employed to investigate the origin of the difference in up-conversion luminescence in the two glasses. Compared with phonon side-band spectroscopy, Raman spectroscopy extracts more information including both phonon energy and phonon density. Our results reveal that the phonon density and the maximum phonon energy of host glasses are both important factors in determining the up-conversion efficiency.     

Luminescence properties of the mixed J-aggregate of oxacyanine dye and thiacyanine dye. Formation of a persistence-type aggregate

The monolayer assemblies incorporating the J-aggregates of oxacyanine dye, N,N'-dioctadecyloxacyanine perchlorate (S9), and thiacyanine dye, N,N'-dioctadecylthiacyanine perchlorate (S11), S9(J) + S11(J), have been fabricated by the Langmuir-Blodgett (LB) technique. The mole fraction X of S11, X = [S11]/([S9] + [S11]), was varied from 0 to 1. Steady-state absorption spectra, fluorescence spectra, and picosecond fluorescence decay curves of the monolayer assemblies have been measured. Spectroscopic properties of the monolayer assemblies incorporating the individual dye aggregates, S9 J-aggregate (S9(J), X = 0) or S11 J-aggregate (S11(J), X = 1), are characterized by a distinct J-band and resonance fluorescence at lambda(ab) = 403 nm and lambda(em) = 403 nm for S9(J) and lambda(ab) = 456 nm and lambda(em) = 463 nm for S11(J). On the other hand, absorption spectra of the S9(J) + S11(J) assemblies for X = 0.1-0.9 display two absorption bands, a shorter wavelength one and a longer wavelength one, whose peak positions are blue-shifted from those of the corresponding J-bands of the S9 J-aggregate and the S11 J-aggregate, respectively. Furthermore, fluorescence spectra are characterized by a single band (longer wavelength fluorescence) which is somewhat blue-shifted from the resonance fluorescence of the S11 J-aggregate. The fluorescence lifetimes of the S11 J-aggregate and isolated S11 molecules in LB films appear to be tau = 110 and 1900 ps, respectively, while the fluorescence lifetime of the longer wavelength fluorescence of the S9(J) + S11(J) assemblies takes practically a constant value of tau = 170-180 ps for X = 0.2-0.8. These observations would indicate that S9 and S11 molecules in the S9(J) + S11(J) assembly can form a specific mixed aggregate distinct from the individual S9 and S11 J-aggregates. From detailed considerations of the former works on luminescence properties of the S9 J-aggregate doped with isolated S11 molecules, as well as the mosaic-type mixed J-aggregate (M-aggregate) composed of a certain thiacyanine dye, 3,3'-disulfopropyl- 5,5'-dichlorothiacyanine sodium salt, and thiacarbocyanine dye, meso-substituted 3,3'-disulfopropyl-5,5'-dichlorothiacarbocyanine potassium salt, it is suggested that S9 and S11 can form a homogeneous aggregate of the persistence type (HP-aggregate). The HP-aggregate is distinguished from the M-aggregate because it is characterized by homogeneous mixing of two component dyes and persistence of two absorption bands.