共查询到20条相似文献,搜索用时 15 毫秒
1.
V. Yu. Plavskii V. A. Mostovnikov G. R. Mostovnikova A. I. Tret’yakova 《Journal of Applied Spectroscopy》2007,74(1):120-132
We have studied the spectral fluorescence and polarization characteristics of Z,Z-bilirubin IXα, at room temperature in chloroform
and in aqueous buffer medium, within an equilibrium complex with human serum albumin (HSA), and also under low temperature
conditions (T = −100°C) in isobutyl alcohol. We have observed a bathochromic shift of the fluorescence spectra, which is most
pronounced for the bilirubin-albumin complex. The following are considered as possible reasons for the observed dependence
of the position of the fluorescence (fluorescence excitation) spectra on the excitation (detection) wavelength: structural
and spectral differences between the chromophores making up the bilirubin molecule; conformational heterogeneity of the pigment
in solution; a contribution to the fluorescence from molecules which have not completed the vibrational relaxation process;
inhomogeneous orientational broadening of the levels; heterogeneity of the microenvironment of the chromophores in the protein
matrix. We show that polarized fluorescence of bilirubin occurs at room temperature, due to the anomalously short fluorescence
lifetime τ (picosecond or subpicosecond ranges). Despite such a short τ, the absorption and emission polarization spectra
suggest the presence of intramolecular nonradiative singlet-singlet energy transfer when bilirubin is excited to high vibrational
sublevels of the S1 state (degree of polarization p = 0.11–0.12). When fluorescence is excited on the long-wavelength slope of the absorption
band, no transfer occurs: the degree of polarization (p = 0.46−0.47) is close to the limiting value (p = 0.50). We discuss
the question of the role played by exciton interactions between chromophores in the bilirubin molecule when it is excited.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 108–119, January–February, 2007. 相似文献
2.
We investigate analytically the effect of the forces that act both in the plane of a scattering surface and normally to it
on the polarized fluorescence of reflected molecules in forward scattering. We show that as the velocity of the beam of incident
molecules increases, the polarization degree of the fluorescence of reflected molecules becomes substantially different from
that of free and/or desorbed molecules. Therefore, the detection of the scattering of molecular beams by a surface using the
polarization degree of fluorescence can serve as a rather reliable means of diagnosing surfaces and determining the modes
of scattering.
Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 2, pp. 205–212, March–April, 1999. 相似文献
3.
The effect of rotational predissociation on the polarization response of an ensemble of photofragments is investigated within
the framework of the model with free scatter of fragments for the most general case when both original molecules and fragments
are asymmetric rotators. Photoinduced decomposition reactions with single- and two-photon excitation of fragment fluorescence
are analyzed. Second- and third-order orientational correlation functions determining the polarization degree of fragment
fluorescence are calculated. The behavior of these correlation functions depending on the shape of original molecules and
fragments, directions of dipole moments, and characteristic times of the process are analyzed.
Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 6, pp. 908–914, November–December, 1998. 相似文献
4.
N. A. Davidenko I. I. Davidenko A. N. Popenaka I. A. Savchenko A. N. Shumelyuk 《Journal of Applied Spectroscopy》2007,74(6):926-928
We have studied the possibility of recording holograms in films of the 4-methacroyloxy-(4′-carboxy-3′-hydroxy)-2-chloroazobenzene
polycomplex with cobalt, with parallel and orthogonal orientation of the light beam polarization. We have shown that these
films can be used as recording media for polarization holography. The characteristic features of relaxation of the diffraction
efficiency of the holograms are connected with cistrans isomerization of the azobenzene groups and the characteristic features
of structural rearrangement in the polymer matrix. We hypothesize that the information-related characteristics of the studied
recording media can be controlled by external electric or magnetic fields, due to the presence of magnetic metal ions within
the polymer film.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 6, pp. 830–832, November–December, 2007. 相似文献
5.
We have considered theoretically the characteristic features of optical detection of nuclear magnetization in the Si/CaF2 structure under the conditions of EPR and NMR by measuring luminescence polarization. We show that application of EPR makes
it possible to detect weak nuclear fields, but the time of spin relaxation of electrons imposes its constraint. The application
of NMR is limited by nuclear fields of no less than 15–20 Gs. The possibility of using optical NMR for direct measurement
of the nuclear field from changes in the luminescence polarization spectrum is shown.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 5, pp. 644–649, September–October, 2005. 相似文献
6.
S. F. Shkirman K. N. Solov’ev T. F. Kachura S. A. Arabei E. D. Skakovskii 《Journal of Applied Spectroscopy》1999,66(1):68-75
Low-temperature (77 K) absorption, fluorescence, and fluorescence-excitation spectra and the fluorescence polarization spectrum
for N-methyl-meso-tetraphenylporphin (N-methyl-TPP) are measured. Based on the polarization spectrum the absorption spectrum
in the visible region (a “generic” porphyrin spectrum) is interpreted. In particular, it is shown that the fifth absorption
band (the “Longo band”) that manifests itself in some porphyrins is a Qy(0–2) band and does not belong to the individual electron transition. Emphasis is placed on the region of the Soret band.
It is inferred that at least two allowed electron transitions (G →Bx and G→By) polarized mutually perpendicularly manifect themselves in this region. The interpretation of the Soret band of porphyrins
[2] that attributes this band to one electron transition G→Bx is thereby rejected. This interpretation is confirmed by computer modeling of the polarization spectrum. Special features
of the experimental polarization spectrum are explained by a more developed vibrational structure and, possibly, a larger
half-width of the Bx band than the half-width of the By band. The contribution of the states of intramolecular charge transfer to the formation of the Soret band is discussed.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 1, pp. 65–72, January–February, 1999. 相似文献
7.
In order to describe the polarization response of an ensemble of molecules undergoing structural transformations (photoisomerization)
under collisionless conditions, we have calculated the orientational correlation functions. We assume that changes in molecular
structure can be considered as instantaneous on the molecular rotation scale. We have obtained general expressions for the
anisotropy when the original molecule and the photoisomer are asymmetric tops. We have performed anisotropy calculations for
steady-state experimental conditions and a number of limiting situations, when the characteristic times of the photoreaction
are much shorter or much longer than the molecular reorientation times and when the original molecule and the photoisomer
are planar tops. We have shown that detecting the polarization response allows us to estimate the characteristic times of
the photoreaction and to determine the intramolecular orientation of the transition dipole moments for transitions with absorption
and emission of light.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 5, pp. 582–587, September–October, 2006. 相似文献
8.
M. Bender K. Rutz P.-G. Reinhard J.A. Maruhn 《The European Physical Journal A - Hadrons and Nuclei》2000,7(4):467-478
We study the influence of the scheme for the correction for spurious center–of–mass motion on the fit of effective interactions
for self–consistent nuclear mean–field calculations. We find that interactions with very simple center–of–mass correction
have significantly larger surface coefficients than interactions for which the center–of–mass correction was calculated for
the actual many–body state during the fit. The reason for that is that the effective interaction has to counteract the wrong
trends with nucleon number of all simplified schemes for center–of–mass correction which puts a wrong trend with mass number
into the effective interaction itself. The effect becomes clearly visible when looking at the deformation energy of largely
deformed systems, e.g. superdeformed states or fission barriers of heavy nuclei.
Received: 6 September 1999 相似文献
9.
The dependence of the fluorescence polarization degree on frequency upon excitation into the first and second electronic bands
of jet-cooled indole has been studied. A structured band consisting of a number of lines rather than a single line has been
recorded in the spectral range of the electronic 1A′-1La-transition. The appearance of the lines is interpreted as the result of nonadiabatic vibronic interaction between the electronic
1La-state and vibronicl states of the indole molecule 1Lb-level. The energy of the unperturbed electronic 1La-level and the orientation of dipole moments near the 1A′-1La-transition have been found.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 3, pp. 319–323, May–June, 2008. 相似文献
10.
We have experimentally studied the characteristic features of a laser beam, polarized at angles of ± 45° to the horizontal
(vertical), passing through plates of varying thickness cut from a CdP2 crystal and placed between crossed polarizers, as a function of their angle of rotation relative to the vertical axis. We
show that a periodic variation in the intensity is connected with the variation in polarization of the laser beam. We have
established that the laser beam remains linearly polarized not only when it passes through the sample along the optic axis,
but also when it travels at up to a 17.5° angle to the optic axis. In this case, the specific rotation of the plane of polarization
along the optic axis is 68.2 degrees/mm for a thicker plate and 83.3 degrees/mm for a thin plate.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 5, pp. 690–693, September–October, 2006. 相似文献
11.
The laws governing polarization of luminescence in the nanostructure Si/CaF2 upon polarization of the spins of the fluorine nuclei by means of optical excitation of charge carriers are considered theoretically.
The possibility of studying experimentally the properties of nuclear spins in analyzing luminescence is shown. The polarization
of luminescence is most informative in the range of excitation rates of charge carriers from 3⋅107 to 3⋅ 108 sec−1 with the CaF2 layer of thickness from 0.6 to 0.8 nm and optical excitation polarization degree of 0.1.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 4, pp. 524–529, July–August, 2005. 相似文献
12.
The influence of nonspecific intermolecular interactions on the fluorescence band shift of 1,3,4-oxadiazole derivatives has
been investigated in the binary solvents hexane-ethanol, toluene-ethanol, toluene-acetonitrile, and carbontetrachloride-2-propanol.
The dependences obtained have been analyzed in terms of preferential solvation. It has been shown that the maximum solvation
energy for slightly polar compounds occurs in toluene-ethanol, toluene-acetonitrile, and carbontetrachloride-2-propanol.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 2, pp. 177–181, March–April, 2008. 相似文献
13.
The spectral and polarization characteristics of trans-isomers ofβ-carotene, lycopene, retinal, and 1,6-diphenylhexatriene (DPH) in solutions have been investigated by the methods of polarized
fluorescence and semiempirical calculations of AM1 and RM3. The high and constant values of the degree of polarization P ∼0.46,
closely coinciding with the limiting value P0=0.5, according to the S2→S0-fluorescence and S2←S0-fluorescence excitation spectra ofβ-carotene and lycopene in n-hexane at room temperature and also high and coinciding according to the S1→S0-fluorescence and S2←S0-fluorescence excitation spectra for retinal in EPA at 77 K and DPH in a polyvinylbutyral film, point to the coincidence of
the directions of absorption and emission oscillators. These oscillators are aligned along the major axis of the polyene molecule,
and the longwave S2←S0-absorption band is formed only by one electronic1B
u
+
←1A
g
−
-transition. The oscillators of shortwave Sa←S0-absorption bands are aligned at an angle to the oscillators of the S2←S0-transitions, which is related to the distortions in the structure of molecules (β-carotene, lycopene) or, as in the case of DPH, to the influence of transitions localized on the orbitals of phenyl rings
and polarized perpendicularly to the major axis of the molecule.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 1, pp. 69–74, January–February, 2000. 相似文献
14.
A. P. Blokhin M. F. Gelin I. I. Kalosha S. A. Polubisok V. A. Tolkachev 《Journal of Applied Spectroscopy》1999,66(1):55-61
The polarization of the fluorescence of radicals formed in laser-induced photodissociation of some disulfides in the gas phase
is measured. Experimental data obtained in the study are interpreted within the free recoil model. It is shown that polarization
experiments carried out to investigate photodecay in vapors allow researchers to uniquely the intramolecular direction of
the dipole moments of transitions with absorption and emission.
Institute of Molecular and Atomic Physics of the National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072,
Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 1, pp. 54–59, January–February, 1999. 相似文献
15.
The value of intrinsic chlorophyll fluorescence polarization, and the intensity in emission spectrum were investigated in
leaf segments of Alocasia macrorrhiza under several stress conditions including different temperatures (25–50°C), various concentrations of NaCl (0–250 mM), methyl
viologen (MV, 0–25 μM), SDS (0–1.0%) and NaHSO3 (0–80 μM). Fluorescence emission spectrum of leaves at wavelength regions of 500–800 nm was monitored by excitation at 436 nm.
The value of fluorescence polarization (P value), as result of energy transfer and mutual orientation between chlorophyll molecules, was determined by excitation at
436 nm and emission at 685 nm. The results showed that elevated temperature and concentrations of salt (NaCl), photooxidant
(MV), surfactant (SDS) and simulated SO2 (NaHSO3) treatments all induced a reduction of fluorescence polarization to various degrees. However, alteration of the fluorescence
spectrum and emission intensity of F685 and F731 depended on the individual treatment. Increase in temperature and concentration of NaHSO3 enhanced fluorescence intensity mainly at F685, while an increase in MV concentration led to a decrease at both F685 and F731. On the contrary, NaCl and SDS did not cause remarkable change in fluorescence spectrum. Among different treatments, the
negative correlation between polarization and fluorescence intensity was found with NaHSO3 treatments only. We concluded that P value being measured with intrinsic chlorophyll fluorescence as probe in leaves is a susceptible indicator responding to
changes in environmental conditions. The alteration of P value and fluorescence intensity might not always be shown a functional relation pattern. The possible reasons of differed
response to various treatments were discussed. 相似文献
16.
We have observed disruption of the energy distribution between chlorophyll-protein complexes, their partial degradation, and
inactivation of photosystem II in green barley leaves under photooxidative stress conditions induced by the photosensitizer
bengal rose.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 2, pp. 266–269, March–April, 2006. 相似文献
17.
We show that when polystyrene is exposed (for 15–60 sec) to a UV laser light beam (λ = 248 nm), its absorption and luminescent
properties change significantly. In the irradiated polymer, optical centers are formed with absorption bands in the 280–460
nm region and fluorescence bands in the 330–520 nm region. We have established the chemical structure of the optical centers
for fluorescence of polystyrene.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 54–58, January–February, 2006. 相似文献
18.
We have recorded the fluorescence excitation spectra of three heterocyclic compounds with a chain structure [BPO (2-phenyl-5-(4-diphenylyl)oxazole),
POPOP (1,4-di[2-(5-phenyloxazolyl)]benzene, and TOPOT (1,4-di[2-(5-n-tolyloxazolyl)]benzene] and the fluorescence spectra
of POPOP, under conditions where the molecules were cooled in an ultrasonic helium jet. A line structure is observed in the
spectra of POPOP and TOPOT; for the BPO molecules, whose configuration changes considerably during electronic excitation,
vibrational structure is apparent only in the low-frequency region of the excitation spectrum, and a diffuse spectrum is recorded
starting from ν
0
0
+ 200 cm−1. For all the compounds, in the spectra we recorded vibrations with frequencies up to 100 cm−1, arising due to the flexibility of the molecular structure. The rotational contours of the lines for the electronic and vibronic
transitions of the POPOP molecules (Trot = 10.5 K) and TOPOT molecules (Trot = 15 K) are structureless and bell-shaped. The degree of polarization of the fluorescence Pfl for the jet-cooled POPOP molecules for excitation of vibrations along the absorption band up to 2000 cm−1 above ν
0
0
is practically constant (∼8.4%) and matches Pfl for high-temperature vapors.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 728–734, November–December, 2006. 相似文献
19.
S. L. Bondarev V. N. Knyukshto A. A. Turban A. A. Ishchenko A. V. Kulinich 《Journal of Applied Spectroscopy》2006,73(1):25-34
We have studied the luminescent spectral properties and calculated the quadratic polarizability of dimethine, tetramethine,
and hexamethine merocyanines based on 1,3-dihydro-1,3,3-trimethyl-(2H)-indol-2-ylidene and malonodinitrile in solutions and
polymer films at room temperature and 77 K. We have shown that increasing the polarity of the solvent and lengthening the
polymethine chain in the studied merocyanines lead to an increase in fluorescence quantum yields and narrowing of the fluorescence
bands. This is explained by the decrease in bond length alternation and weakening of vibronic interactions in the singlet-excited
fluorescent state. The mirror symmetry in the structured absorption and fluorescence spectra of merocyanine dyes in ethanol
at 77 K, observed here for the first time, is due to enhancement of electrostatic interactions of the merocyanine and solvent
molecules. Increased stiffness of the medium considerably decreases the probability of nonradiative processes, and the major
channel for deactivation of the electronic excitation energy at 77 K is fluorescence. The higher values of the quadratic polarizability
(6.0·10−28 esu in ethanol and 3.3·10−28 esu in chloroform) for hexamethine merocyanine, estimated by the solvatochromic method, lets us consider this compound as
a promising material for designing nonlinear optical converters for harmonics of laser radiation.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 26–35, January–February, 2006. 相似文献
20.
B. Ananthanarayan S.D. Rindani 《The European Physical Journal C - Particles and Fields》2006,46(3):705-712
We approach the issue of the discovery of new physics at high energies associated with the proposed International Linear
Collider in the presence of longitudinal as well as transverse electron and positron beam polarization. We determine the beam
polarization dependence and the angular distribution of a particle of arbitrary spin in a one-particle inclusive final state
produced in e+e- collisions through the interference of γ or Z amplitude with the amplitude from new interactions having arbitrary space–time
structure. We thus extend the results of Dass and Ross, proposed at the time of the discovery of neutral currents, to beyond
the standard model currents. We also extend the case of e+e- annihilation in the s-channel to the production of bosons due to t- and u-channel processes. Our work provides an approach
to model-independent determination of the space–time structure of beyond the standard model interactions. We briefly discuss
applications of the framework to popular extensions of the standard model, and demonstrate that our framework is general enough
to account for certain results in the minimal supersymmetric standard model. 相似文献