共查询到20条相似文献,搜索用时 15 毫秒
1.
A. S. Lebed S. L. Yefimova G. Ya. Guralchuk A. V. Sorokin I. A. Borovoy Yu. V. Malyukin 《Journal of Applied Spectroscopy》2010,77(2):183-188
The interaction of a series of cationic dialkyloxacarbocyanine perchlorate (DiOC
n
) dyes of different degrees of hydrophobicity with micelles of an anionic surfactant, sodium dodecylsulfate (SDS), has been
studied spectrophotometrically in aqueous solutions. The Benesi–Hildebrand equation was used to calculate binding constants
(K
b
) of the dyes to surfactant micelles, the fraction of dye bound to the micelles (f
mic
), and the standard free-energy change (ΔG
0) for the transfer of dye from the aqueous to micellar phase. It has been shown that the interaction of oppositely charged
dye molecules and surfactant micelles is controlled by both electrostatic and hydrophobic interactions. A small increase in
dye hydrophobicity due to lengthening of the hydrocarbon radical has been shown to cause an abrupt nonlinear increase of the
fmic value. This points to a key role of hydrophobic interactions in the binding of dye molecules with the micelles. 相似文献
2.
The structure and spectral properties of two organic ruthenium complexes used as sensitizing dyes for solar batteries (well-known
N3 dye and its selenophene-conjugated analogue C105 ([Ru(bpy)(bpysef)(COOH)2(NCS)2] (bpy = 2,2′-bipyridine, bpysef = 4,4′-bis(5-hexylselenophene-2-yl)2,2′-bipyridine)) are comparatively studied within the
density functional method. It is shown that the conjugation of the bipyridine ligand with selenophene affects the electronic
structure of the C105 dye. A multilevel model for interpreting the electronic spectra of dyes is proposed based on the analysis
of the shapes of molecular orbitals. The nature of the absorption bands of these ruthenium complexes in the region of 300–800
nm is explained. It is found that, in the polar acetonitrile solvent, these dyes are negatively solvatochromic, which agrees
with the current classical views on the effect of the solvent on the shape of electronic absorption spectra of related compounds. 相似文献
3.
The constants of binding dye molecules with the micelles of sodium dodecyl sulfate are determined using quenching of delayed fluorescence of acridine dyes by sodium iodide in aqueous–micellar solutions. Kinetic equations have been composed that describe the processes of deactivation of the excited states of dyes. By solving these equations at the concentration of the quencher sodium iodide corresponding to the minimum lifetime of triplet states and at the concentration of micelles corresponding to the least value of the delayed fluorescence quenching rate constants, we obtained the constants of binding dyes with micelles equal to 1.3·107, 2.9·107, and 3.1·107 M–1 for trypaflavine, acridine orange, and acridine yellow, respectively. We calculated the rate constants of quenching of the triplet states of the molecules of dyes by iodide ions (I
–) that decreased in transition from trypaflavine to acridine orange and acridine yellow. 相似文献
4.
An exciplex halogen source of UV radiation that is excited by an rf transverse discharge is studied experimentally. The active
medium of the source is an Ar-Xe-Cl2 mixture kept at a low pressure (100–1000 Pa), and its working spectral range is 220–450 nm. The radiation spectrum contains
235 nm XeCl(D-X), 257 nm Cl2(D′-A′), 306 nm XeCl(B-X), 390 nm XeCl(C-A), and 430 nm XeCl(B-A) lines. The results of optimization of the UV power as a function of the pressure, Ar-Xe-Cl2 mixture composition, and excitation power are reported. 相似文献
5.
I. D. Petrov T. Peters T. Halfmann S. Aloïse P. O'Keeffe M. Meyer V. L. Sukhorukov H. Hotop 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(2):181-193
The even parity mp1/2
5np′ and mp1/2
5nf′ autoionizing resonances of Ar, Kr, and Xe (m=3,4,5) were investigated experimentally and theoretically by one-photon
excitation from lower-lying intermediate levels. In particular, high
resolution measurements for the Ar(nf′), Kr(12p′,8f′), and Xe(8p′)
resonances are reported; lineshape parameters for these resonances have been
derived by a Fano-type analysis, thus yielding reduced resonance widths. The
experimental spectra and the resonance parameters are compared with
theoretical calculations which are based on the configuration interaction
Pauli–Fock approach including core polarization. The measured and
calculated lineshapes are in good agreement. In addition, theoretical predictions are presented
for other resonances, which have not yet been observed experimentally, and some
systematic trends are elucidated. 相似文献
6.
Thioflavin T (ThT) has been widely employed to detect amyloid fibrils in tissues and recently in presence of SDS micelles.
However, the contribution of membranes or micelles to ThT fluorescence has never been investigated. In this paper, we show
for the first time that the anionic micellar microenvironment of SDS has a profound impact on the absorption and fluorescence
spectra of ThT in sharp contrast to cationic (CTAB) and neutral micelles (Triton X-100 & Tween 20). Unlike CTAB or Triton
X-100 or Tween 20 micelles, formation of SDS micelles shifts the λmax for ThT absorption from 412 nm in buffer to 428 nm inside the micelle, with a 28% increase in the peak molar absorptivity
and a ∼13 fold increase in ThT fluorescence (λmax = 489 nm). Extending these observations to cell plasma membranes, we show that ThT can quickly enter and appear selectively
fluorescent inside mammalian cells like BHK21 and HT29, against a dark background owing to negligible fluorescence from free ThT in aqueous medium. The above results suggest that
ThT can be a useful probe for live cell imaging and for selectively labeling micelles on the basis of the charge in the polar
headgroup.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
7.
D. A. Rudakov V. I. Potkin A. N. Ryabtsev I. B. Sivaev 《Journal of Applied Spectroscopy》2006,73(4):616-619
In the 11B NMR spectra of dihalo derivatives of bis(dicarbollyl)cobalt(III), we have identified a correlation between the 11B NMR chemical shifts of substituted boron atoms and boron atoms found in other positions on the carborane skeleton. We have
observed an increased shielding effect for fluorine atoms (compared with other halogens), manifested in an upfield shift of
the 11B NMR signals for antipodal and trans boron atoms. For the fluorine-containing compound Bu4N+ [8,8′-F2-3,3′-Co(1,2-C2B9H10)2]−, we propose the following sequence of electron density transfer: B(8) → {B(6) and B(10)} → B(4, 7).
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 547–549 (cont.), July–August, 2006. 相似文献
8.
Kurtaliev EN 《Journal of fluorescence》2011,21(4):1713-1719
The spectral-luminescent characteristics of newly synthesized styrylcyanine dyes on the base of dyes Sbo ((E)-2-(4-(dimethylamino)styryl)-3-methylbenzo[d]oxazol-3-ium
iodide) and Sil ((E)-2-(4-(dimethylamino)styryl)-1,3,3-trimethyl-3H-indolium perchlorate) in aqueous solutions without and
in the presence of bovine serum albumin (BSA) were studied. It was established that the absorption spectra of dyes Tol-6,
Dbo-10 and Dil-10 with increasing amount of BSA appear new bands with λmax = 505 nm, λmax = 512 nm and λmax = 566 nm, respectively, whose intensity increases in proportion to the amount of albumin. The intensity of the glow of the
main band of fluorescence in the presence of BSA sharply increases. The binding constant (K) and the number of binding sites
(N) of studied dyes with BSA were determined. The dependence of binding constants with BSA on the dipole moment of dye molecules
was determined, which indicates that besides electrostatic forces of attraction between molecules styrylcyanine dyes with
BSA, hydrophobic interactions are essential. 相似文献
9.
Leavens BB Trindle CO Sabat M Altun Z Demas JN DeGraff BA 《Journal of fluorescence》2012,22(1):163-174
The synthesis of some heteroleptic, cyclometalated iridium(III) complexes is described. The utility of these [Ir(ppy)2(N-N)]Cl (ppy = 2-phenylpyridine and N-N = substituted bipyridine, biquinoline, or phenanthroline) complexes as luminescence-based
sensors is assessed. The emission intensity of an Ir(III) complex featuring the 3,3′-Hndcbpy ligand (Hndcbpy = dicarboxylic acid-2,2′-bipyridine; n = 0,1,2 to indicate deprotonated, mono- and diprotonated species, respectively) is seen to increase in the presence of Pb(II).
Insight into the structure and analyte-sensing capability is achieved by X-ray crystallography in conjunction with computational
modeling. Complexes incorporating carboxylic acid-functionalized bipyridine and biquinoline as the polypyridyl ligand show
pH sensitivity while similar phenanthroline complexes do not. 相似文献
10.
The luminescence properties of Re(I) complexes incorporating the dcbpy ligand (dcbpy = n,n′-dicarboxylic acid-2,2′-bipyridine; n = 3, 4) were investigated as well as their utility as Pb2+ sensors. An unusual binuclear complex of the 3,3′- species was isolated. The emission intensity and lifetime for all complexes
were found to be highly temperature-dependent, with quantum yields and lifetimes dramatically greater at 77 K than at room
temperature. The monomeric 3,3′-dcbpy Re(I) complex demonstrates nearly 1:1 binding with Pb2+. The effect of this lead binding on the emission intensity is great, but the low quantum yields allow only for detection
of the metal at the micromolar level. The binding of Pb2+ to the 4,4′-dcbpy complex is modeled and the interaction is demonstrated to involve two binding sites. 相似文献
11.
Shilpa M Nagababu P Kumar YP Latha JN Reddy MR Karthikeyan KS Gabra NM Satyanarayana S 《Journal of fluorescence》2011,21(3):1155-1164
Three symmetric ligands 7-methyl dipyrido-[3,2-a;2′,3′-c]phenazine (dppz-CH3), 7-nitro dipyrido-[3,2-a;2′,3′-c]phenazine (dppz-NO2) and benzo[i]dipyrido-[3,2-a;2′,3′-c]phenazine (dppn) and their ruthenium(II) complexes [Ru(en)2(L)][ClO4]2 (en= ethylenediamine), L= dppz-CH3, dppz-NO2 and dppn have been synthesized and characterized by IR, 1H, 13C NMR and Mass spectra. The interactions of these complexes with calf thymus DNA have been investigated by spectrophotometric,
spectrofluorimetric, circular dichroism, viscosity and thermal denaturation studies. As the planar extension of the intercalative
ligand increases, the interaction of the complex with DNA increases, indicating that the size and shape of the intercalalative
ligand has a marked effect on the strength of interaction. The plot of log K versus log [Na+] yield a slope of -1.26, -1.53, -1.60 for the complexes 1, 2 and 3 respectively. These three complexes have been found to
promote the cleavage of plasmid pBR 322 DNA upon irradiation. 相似文献
12.
J. K. Baria 《Czechoslovak Journal of Physics》2004,54(4):469-485
A model pseudopotential depending on an effective core radius but otherwise parameter free is used to study the interatomic
interactions, phonon dispersion curves (inq and r-space analysis), phonon density of states, mode Grüneisen parameters, dynamical elastic constants (C
11,C
12 andC
44), bulk modulus (B), shear modulus (C′), deviation from Cauchy relation (C
12–C
44), Poisson’s ratio (σ), Young’s modulus (Y), behavior of phonon frequencies in the elastic limit independent of the direction (Y
1), limiting value in the [110] direction (Y
2), degree of elastic anisotropy (A), maximum frequencyω
max, mean frequency 〈ω〉, 〈ω
2〉1/2=(〈ω〉/〈ω
−1〉)1/2, fundamental frequency 〈ω
2〉, and propagation velocities of the elastic constants in Cu, Ag, Au, Ni, Pd, and Pt. The contribution of s-like electrons
is calculated in the second-order perturbation theory for the model potential while that of d-like electrons is taken into
account by introducing repulsive short-range Born-Mayer like term. Very recently proposed screening function due to Sarkar
et al. has been used to obtain the screened form factor. The theoretical results are compared with experimental findings wherever
possible. A good agreement between theoretical investigations and experimental findings has proved the ability of our model
potential for predicting a large number of physical properties of transition metals. 相似文献
13.
The rare t-quark decays t → cl
j
+
l
k
−
and t → cṽ
j
k
k
induced by scalar-leptoquark doublets are considered within the minimal model involving four-color quark-lepton symmetry
and the Higgs mechanism of quark and lepton mass splitting. The partial widths with respect to the decays being considered
and the total widths Γ(t → cl
+′l
−) = Σj,k Γ(t → cl
j
+
l
k
−
) and Γ(t → cl
+′l
−) = Σj,kΓ(t → cṽ
j
v
k
) with respect to, respectively, the charged leptonic and neutrino modes are calculated. It is shown that, at scalar-leptoquark
masses higher than the t-quark mass (m
S > m
t), the branching ratios for these modes are Br(t → cl
+′l
−) ≈ (3.5−0.4) × 10−5 and Br(t → cṽ′v) ≈ (7.1−0.8) × 10−5 at m
s
= 180–250 GeV and an appropriate value of the leptoquark-mixing angle (sin β ≈ 0.2) and can increase for m
S < m
t to Br(t → cl
+′l
−) ≈ 0.03−0.002 and Br(t → cl
+′l
−) ≈ 0.46−0.05 for the charged mode at m
S
= 150–170 GeV for sin β ≈ 1 and sin β ≈ 0.2, respectively. In the cases being considered, t-quark decays to pairs of charged leptons can be accessible to detection at LHC. In the last case, these decays could manifest
themselves (for example, in dilepton events) at the Tevatron as well.
Original Russian Text ? P.Yu. Popov, A.D. Smirnov, 2006, published in Yadernaya Fizika, 2006, Vol. 69, No. 6, pp. 1006–1016. 相似文献
14.
Steffen Härtel Svitlana Tykhonova Marcus Haas Horst A. Diehl 《Journal of fluorescence》2002,12(3-4):465-479
Fluorescence spectroscopy and microscopy are powerful techniques to detect dynamic properties in artificial and natural lipid membrane systems. Unfortunately, most fluorescent dyes that sense dynamically relevant membrane parameters are UV sensitive. Their major disadvantage is a high susceptibility to fluorescence bleaching. Additionally, the risk for hazardous damages in biological components generally increases with decreasing excitation wavelength. Therefore the use of non-UV–sensitive membrane dyes would provide significant advantage, particularly for applications in fluorescence microscopy, which usually implies high local excitation intensities. We applied steady-state fluorescence spectroscopy techniques to several UV and non-UV membrane dyes to detect and compare dynamically relevant excitation and emission characteristics. Small unilamellar liposomes (composed of egg yolk phosphatidylcholine) served as a model system for biological membranes. The dynamic properties of the membranes were varied by two independent parameters: the intrinsic cholesterol content (0–50 mol%) and temperature (10–50°C). We tested four non-UV–sensitive membrane dyes: 9-diethylamino-5H-benzophenoxazine-5-one (Nile Red), 4-(dicyanovinyl)julolidine (DCVJ), N-(3-triethylammoniumpropyl)-4-(4-(dibutylamino)styryl) pyridinium dibromide (FM 4-64), and 1,1-dioctadecyl-3,3,3,3-tetramethylindocarbocyanine perchlorate (DiIC18). We also tested three derivatives of DiIC18: DiIC16 and DiIC12 differ in acyl chain length and Fast-DiIC18 provides double bonds between hydrocarbon atoms. The spectral results were compared to established fluorescence characteristics of four UV membrane dyes: the anisotropy of 1-6-phenyl-1,3,5,-hexatrien (DPH), two derivatives of DPH (TMA-DPH and COO–-DHP), and the generalized polarization of 6-dodecanoyl-2-dimethyl-aminonaphthalene (Laurdan). Our results indicate that the tested non-UV dyes do not reveal dynamically relevant membrane parameters in a direct manner. However, spectral characteristics make DiIC18, Nile Red, and DCVJ promising probes for the microscopic detection of lateral lipid organization, an indirect indicator of membrane dynamics. In particular, DiIC18 showed very selective shifts in the emission spectra at defined temperatures and cholesterol contents that have not been reported elsewhere. 相似文献
15.
R.B. López-Martens T.W. Schmidt G. Roberts 《Applied physics. B, Lasers and optics》2002,74(6):577-581
The cycle-averaged ac Stark effect associated with the [
A
]2Σ+v′=2?[
X
]2Π1/2v′=0 two-photon absorption of NO at intensities between 7.7 and 15.2 TW cm-2 has been characterized in real time through a synergic combination of bichromatic laser experiments and quantum-dynamics
calculations. Measurements of the fluorescence emitted by the Rydberg [
A
]2Σ+v′=2 level as a function of time between Stark and probe components of a bichromatic field exhibit a characteristic evolution
in temporal peak structure with Stark-field intensity, which is interpreted in terms of a time-dependent Floquet analysis
of the laser–matter interaction. The experimental observations are consistent with a dynamic Stark shift of Δεs(ω1,ω2)≤0.23 eV of the optical transition at these intensities.
Received: 18 January 2002 / Revised version: 6 March 2002 / Published online: 24 April 2002 相似文献
16.
Zhaokui Wang Shigeki Naka Hiroyuki Okada 《Applied Physics A: Materials Science & Processing》2011,102(3):681-687
Injection properties of electrons and holes in a mixed single layer organic light emitting device with mixed small molecules
tris-(8-hydroxy-quinoline) aluminum (Alq3), 2,5-bis(6′-(2′,2″-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy), 4′-bis[N-(1-napthyl)-N-phenyl-amino]biphenyl
(α-NPD), and 5,6,11,12-tetraphenylnaphthacene (rubrene) were investigated using Au/MoO3 as hole and Al alloy as electron injection electrodes. On the basis of measuring the temperature dependence of currents through
the interface between the electrodes and the mixed single organic layer, the carrier injection mechanism was primarily ascribed
to the Schottky thermionic emission with the barrier height of 0.25 eV for holes and 0.67 eV for electrons. By adding the
dopant material rubrene and the electron transport material PyPySPyPy into the mixed single layer, the barrier height of electrons
could be reduced. The interfacial state analysis demonstrated that the electron barrier height was also dependent on the interfacial
conditions of the device. 相似文献
17.
The energy and centrality independence of the limiting fragmentation for produced mesons have been used to extract the reduced
pseudorapidity (η′ = η − η
beam
) distributions of charged baryons at forward rapidity. The distribution crosses at η′ ≈ = −1 suggesting the prominence of beam protons above that rapidity. The loss of beam rapidity has been extracted which
has been found to increase with centrality. 相似文献
18.
N. M. Olekhnovich A. V. Pushkarev Yu. V. Radyush 《Journal of Applied Spectroscopy》2009,76(4):518-522
A technique for analysis of the electric modulus spectrum of dielectric ceramics based on the elimination of the direct current
conductivity (σ
dc
) contribution has been developed. Expressions are given for the real (M′
ac
) and imaginary (M′′
ac
) parts of the complex electrical modulus related only to the dielectric polarization and not containing the contribution
of σ
dc
. The frequency dependence of M′′
ac
and the M′′
ac
– M′
ac
diagram for BiMg1/2Ti1/2O3 and BiMg1/2Zr1/2O3 perovskite ceramics are analyzed. 相似文献
19.
We present the results of an investigation of a short-wavelength radiation source (Δλ = 130–350 nm) with excitation by a transverse
high-frequency (f = 1.76 MHz) discharge based on a mixture of argon and chlorine (p = 100–500 Pa). We have studied the spectral
characteristics of the plasma, the oscilloscope traces of the voltage, the current and emission of the discharge, the dependence
of the power of the emission on the electrical power of the discharge, and also the pressure and partial composition of the
Ar/Cl2 mixture. The UV-VUV source emits in a system of broadened and overlapping ArCl(B/X), Cl2(D′/A′), and Cl**2 molecular bands.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 648–651, September–October, 2007. 相似文献
20.
H.Y. Wang Z.W. Ma E.Y. Jiang Y.J. He H.S. Huang 《Applied Physics A: Materials Science & Processing》1999,68(5):559-562
The structure and magnetic properties of Fe-N and Fe-Ti-N films have been studied as a function of annealing temperature Ta with a transmission electron microscope and a vibrating sample magnetometer. The as-prepared Fe-N films consist of the γ′-Fe4N and α′′-Fe16N2 phases, and the Fe-Ti-N films are composed of the γ′-Fe4N, α′′-Fe16N2, and TiN phases. The structural changes with annealing temperature in the Fe-N films are distinct. The α′′-Fe16N2 decomposes into α+γ′ phases in the Fe-N film annealed at about 300 °C, and it disappears in the film annealed at 350 °C. Annealing of the Fe-Ti-N
films shows no structural changes between room temperature (RT) and 500 °C. The saturation magnetization 4πMS and coercivity Hc of the Fe-N films change drastically with the annealing temperature Ta, whereas those of the Fe-Ti-N films do not change with Ta up to 500 °C. These results indicate that the additon of Ti may improve the thermal stability of Fe-N films.
Recieved: 6 Juli 1998 / Accepted: 19 Oktober 1998 / Published online: 10 March 1999 相似文献