共查询到20条相似文献,搜索用时 484 毫秒
1.
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
2.
A. V. Borodin V. Ya. Gayvoronsky O. D. Kachkovsky Ya. A. Prostota A. V. Kargovski? M. M. Nazarov D. A. Sapozhnikov Yu. L. Slominski? I. N. Smirnova A. P. Shkurinov 《Optics and Spectroscopy》2009,107(4):505-514
The low-frequency vibrational modes of the series of merocyanines (malononitrile derivative) have been investigated by pulsed
terahertz spectroscopy. The terahertz absorption spectra are shown to contain both intermolecular and intramolecular vibrational
modes in the range of 0.15–3.45 THz (5–115 cm−1). An unambiguous correlation is established between the purposeful modification of the molecular structure of merocyanine
dyes and the change in their terahertz absorption spectra. 相似文献
3.
V. V. Uglov V. I. Shimanski D. P. Rusalsky M. P. Samtsov 《Journal of Applied Spectroscopy》2008,75(4):546-549
The structure of ultradispersed diamonds (UDD) is studied by spectral methods. The presence of diamond crystal phase in the
UDD is found based on x-ray analysis and Raman spectra. The Raman spectra also show sp2-and sp3-hybridized carbon. Analysis of IR absorption spectra suggests that the composition of functional groups present in the particles
changes during the treatment.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 4, pp. 524–528, July–August, 2008. 相似文献
4.
G. A. Zalesskaya V. S. Ulashchik N. P. Mit’kovskaya O. V. Laskina A. V. Kuchinskii 《Journal of Applied Spectroscopy》2007,74(5):738-743
We used IR Fourier absorption spectra of blood to study changes in the structure of globular blood proteins with extracorporeal
autohemomagnetotherapy, used to treat ischemic heart disease. We compare the spectra of blood before and after magnetotherapy
in the regions: amide I (1655 cm−1), amide II (1545 cm−1), amide III (1230–1350 cm−1), amide IV and amide V (400–700 cm−1). We have shown that pronounced changes in the spectra in the indicated regions on direct exposure of blood in vivo to a
low-frequency pulsed magnetic field are connected with conformational changes in the secondary structure of globular blood
proteins, which are apparent in the increase in the contribution of the α-helix conformation. We discuss the magnetotherapy-initiated
appearance of new IR absorption bands at 1018 and 1038 cm−1 and an increase in the intensity of a number of other bands located in the 1000–1200 cm−1 region, which suggests a change in the concentration of some blood components.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 665–669, September–October, 2007. 相似文献
5.
V. A. Pushkarchuk S. Ya. Kilin A. P. Nizovtsev A. L. Pushkarchuk A. B. Filonov V. E. Borisenko 《Journal of Applied Spectroscopy》2007,74(1):95-101
We have used the density functional method to model the atomic and electronic structure of diamond nanocrystals passivated
by hydrogen atoms and either not containing defects or containing a single [NV]− center. We have shown that in all cases, after relaxation the nanocrystals are formed as diamond-like structures.
We have studied the features of the electronic structure of the nanocrystals. We have analyzed in detail the mechanism for
the formation of energy levels in the bandgap due to [NV]− centers. We have established that the optical absorption and fluorescence spectra for the [NV]− centers are mainly associated with transitions of electrons between the highest occupied β orbitals (projection of the electron
spin equal to +1/2) and lower unoccupied α orbitals (projection of the electron spin equal to −1/2). The results on the localization
and energy position of the states in the bandgap match data obtained for the [NV]− center in bulk diamond.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 86–92, January–February, 2007. 相似文献
6.
Spectral-luminescent properties and photoinduced transformations of bisanthene and bisanthenequinone
Based on the study of photochemical transformations of bisanthene in oxygen-containing solutions, it was established that
the final product of this reaction is bisanthenequinone. It is shown that in the course of this oxidation reaction the intermediate
compounds endomonoperoxide and bisanthene endobiperoxide are formed. Quantum-chemical calculation of the geometrical structure
and electronic spectra of the endoperoxides has shown that they have a nonplanar structure, and their absorption spectra experience
a large hypsochromic shift. The absorption and fluorescence spectra of solutions of bisanthene in different solvents at 300
and 77 K were investigated. The large Stokes shift of the fluorescence spectra of the solutions of bisanthene in benzene and
in its methyl derivatives is explained by the action of intermolecular interactions. The quasi-line fluorescence spectra of
solutions of bisanthene in the matrices of saturated hydrocarbons were recorded.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 2, pp. 176–182, March–April, 2000. 相似文献
7.
The absorption and photoluminescence spectra of a number of derivatives of 3,3,6,6-tetramethyl-N-phenyl-decahydroacridine-1,8-dione
with a regular change in the structure of molecules are investigated. Their electronic structure is calculated. The nature
of some of the spectral bands is established. Significant differences in the efficiency of the processes of photochemical
transformations of dyes exposed to UV irradiation have been revealed; these changes are attributable to the different donor-acceptor
properties of the substituents introduced. A mechanism of phototransformations that agrees with both calculations of the electronic
structure of molecules and the spectral-luminescent characteristics of the initial and irradiated compounds is suggested.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 4, pp. 454–459, July–August, 2005. 相似文献
8.
S. M. Arabei 《Journal of Applied Spectroscopy》1998,65(4):560-566
Monochromatic photoexcitation and selective registration in bands of purely electronic S1↔S0 transitions resulted in fine fluorescence and absorption (fluorescence excitation) spectra of hypericin in polyvinylbutyral
at a temperature of 4.2 K. Vibration analysis of the spectra is done and conclusions are made about the form of many normal
vibrations. It is found that the formation of intramolecular hydrogen bonds in the hypericin structure has a substantial effect
on the relative position of the electronic vibrational levels of the pigment molecule.
Institute of Molecular and Atomic Physics of the National Academy of Sciences of Belarus, 70, F. Skorina ave., Minsk 200072,
Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 4, pp. 539–545, July–August, 1998. 相似文献
9.
We have used the IR absorption spectra of blood, plasma, and packed erythrocytes to study the effect of in vivo exposure of
blood to low-intensity emission from a He–Ne laser (λ = 632.8 nm, 4 mW/cm2) on the molecular components of blood. In comparing the IR spectra of samples of blood sample and blood components before
and after irradiation, we identified changes in the amide A, amide I, amide II, amide III absorption regions and also in the
absorption bands of methyl, methylene, and phosphate groups. We conclude that exposure of blood in vivo to emission from a
He–Ne laser leads to a decrease in the contribution of the α-helix conformation in the secondary structure of the blood proteins. 相似文献
10.
N. Volbers H. Zhou C. Knies D. Pfisterer J. Sann D.M. Hofmann B.K. Meyer 《Applied Physics A: Materials Science & Processing》2007,88(1):153-155
This work investigates cobalt doped ZnO nanoparticles prepared by using wet chemical methods. The nanoparticles have a typical
size of 3–8 nm. The electronic structure as well as the optical and magnetic properties of Co2+ have been characterized. X-ray diffraction spectra of the powder show wurtzite ZnO with no secondary Co phases. In the energy
range below the bandgap, the optical absorption spectra show the internal d–d transitions related to Co2+ incorporated on the Zn lattice site in ZnO. Low temperature photoluminescence measurements confirm these results. Based on
the analysis of the g-valuesfor bulk ZnO:Co., electron paramagnetic resonance measurements coincide with the simulation of
Co-doped ZnO powder. Thus far, no evidence for ferromagnetism has been obtained.
PACS 61.46.Df; 76.30.Fc; 78.67.Bf 相似文献
11.
A Fourier transform electron paramagnetic resonance (FT-EPR) study was made of the photochemistry of 3,4-methylenedioxyphenol (sesamol, SEOH)) in aqueous solution. FT-EPR measurements show that in alkaline (pH 11) solution, pulsed-laser excitation of SECT leads to photoionization giving the hydrated electron and SEO⋅ free radical. Resonance signals from these paramagnetic species develop with instrument-controlled rise time. They exhibit a low-field emission/ high-field absorption (E/A) CIDEP pattern with the transition from emission to absorption occurring at the resonance of the hydrated electron. It is shown that the spin polarization stems from contributions from the ST0 radical pair mechanism (E/A) and triplet mechanism (A). From this it is concluded that photoionization of sesamol occurs via the triplet excited state. In neutral and acidic (pH 4–7) aqueous solution, photoexcitation generates SEO⋅ and cyclohexadienyl-type radicals. In this case, radicals grow in over a period of 1–2 μs and FT-EPR spectra display an E/A pattern with the inversion point in the center. The lowering of the pH of the solution apparently is accompanied by a strong reduction in the relative importance of photoionization. From the FT-EPR data it can be deduced that in neutral and acidic solutions the dominant reaction channel is H-atom transfer. In this respect, the photochemistry of sesamol differs from that of phenol andp-cresol. For these phenols the change in pH does not affect the appearance of the FT-EPR spectra. Apparently, the change in electronic structure caused by the methylenedioxy substituent strongly affects the excited state reactivity of sesamol. 相似文献
12.
B. Grouiez V. Zeninari L. Joly B. Parvitte 《Applied physics. B, Lasers and optics》2010,100(2):265-273
Pulsed quantum-cascade-laser spectrometers are usually used to detect atmospheric gases with either the interpulse technique
(short pulses, typically 5–20 ns) or the intrapulse technique (long pulses, typically 500–800 ns). Each of these techniques
has its drawbacks. Particularly the gas absorption spectra are generally distorted. We have previously developed another technique
called intermediate-size pulses (typically 50–100 ns) technique for gas detection using pulsed QCL spectrometers. In this
paper, infrared spectra of ammonia recorded with this technique in the 10 μm region are presented. For the NH3 spectra recorded at low pressure (i.e. in the mbar range), the spectra show typical oscillations after the absorption. The
Beer–Lambert law cannot explain these oscillations, termed the rapid-passage effect. Comparisons between experimental and
calculated spectra will be realized. This phenomenon is not satisfactory from a spectroscopic point of view and spectra must
be recorded at higher pressures. For the NH3 spectra recorded at higher pressure (i.e. in the 50 mbar range), the oscillations disappear and the Beer–Lambert law could
be reused. This paper will demonstrate that the intermediate-size technique gives reliable measurements for NH3 detection. Moreover the typical apparatus function (0.003 cm−1 HWHM) is far lower from the typical apparatus function of the interpulse QCL spectrometers (0.015 cm−1 HWHM). 相似文献
13.
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
14.
J. Thirumalai R. Chandramohan M. Sekar R. Rajachandrasekar 《Journal of nanoparticle research》2008,10(3):455-463
Small particles of trivalent europium doped yttrium oxysulfide nanocrystals (ϕ ∼ 7 nm) were synthesized using sol–gel polymer
thermolysis. The nanocrystals show significant change in the excitation bands corresponding to fundamental absorption and
charge transfer absorption bands. The optical spectra essentially comprise of two parts: fundamental absorption (∼260 nm)
and Eu3+–X2− ligand (O2−/S2−) charge transfer (∼290 nm) bands. They show significant blue shifts (0.24–0.30 eV), respectively, with respect to the bulk
counterpart. These may be explained by considering possible size dependent changes associated with quantum confinement effect
in this large bandgap semiconductor system. FT-IR spectra revealed the difference in chemisorbed species between bulk and
nanocrystalline samples. The results of the solid-state photo-induced electrical impedance spectroscopy studies are reported. 相似文献
15.
I. G. Motevich N. D. Strekal’ J. W. Nowicky S. A. Maskevich 《Journal of Applied Spectroscopy》2007,74(5):666-672
We have studied the absorption, fluorescence, and surface-enhanced Raman scattering (SERS) spectra of sanguinarine using a
silver hydrosol and an electrochemical cell with a silver working electrode for different pH values in the medium. We carried
out quantum chemical calculations in order to interpret the electronic and vibrational spectra and to establish their correlations
with the structure of the molecules. We optimized the structure and determined the spectral characteristics of the cationic
and neutral forms of the sanguinarine molecules in solution and adsorbed on the surface of an anodized Ag electrode for different
potentials.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 604–609, September–October, 2007. 相似文献
16.
V. A. Svetlichnyi M. P. Samtsov O. K. Bazyl’ O. V. Smirnov D. G. Mel’nikov A. P. Lugovskii 《Journal of Applied Spectroscopy》2007,74(4):524-532
We present results of experimental and theoretical studies of the optical characteristics of a new indotricarbocyanine dye
that is capable of effectively limiting the power of laser radiation in the visible spectral range. The spectral-luminescent
and energy characteristics of the dye molecules and their absorption spectra from the excited state with nanosecond resolution
are investigated experimentally. Quantum-chemical methods are used to calculate electronic absorption spectra from the ground
(S0 → Sn) and excited (S1 → Sn) states and to determine the nature of electronic states of the molecule and the rate constants of intramolecular photophysical
processes. The results of the theoretical research agree with experimental data. It is shown that the investigated dye has
singlet-singlet absorption at 400–600 nm. Nonlinear absorption of the dye upon excitation by radiation of the second harmonic
of a Nd:YAG laser is studied by z-scanning with an open diaphragm. The ratio of dye absorption cross sections from the excited
and ground states at 532 nm is determined in the framework of a three-level model. The results are compared with those for
previously studied compounds.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 4, pp. 473–480, July–August, 2007. 相似文献
17.
Methods of quantum chemistry (including the method of intermediate neglect of differential overlap (INDO)) are used to calculate
and to interpret the absorption and fluorescence spectra of the 9-11-dehydroderivative 2,3-dimethoxy-8-aza-D-homogon-1,3,5(10),13-tetraene-12,17a-dion
(DA-1) molecule in aproton and proton-donor solvents. The electronic structure and spectra of electronically excited states of
the isolated molecule and its complexes with water and proton solvates are calculated. It is demonstrated that bands in the
absorption spectra are complex; they are formed by two or more electron transitions. It is established that only the charged
DA-1 + H
5
O
2
+ and DA-1 + 2H
3
O
+ complexes can fluoresce.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 3–9, June, 2006. 相似文献
18.
R. M. Vlasova N. V. Drichko O. O. Drozdova R. N. Lyubovskaya 《Physics of the Solid State》1997,39(8):1165-1170
The reflection spectra and optical conductivity spectra of the new organic conductor ϰ-(ET)2[Hg(SCN)2Cl] with a metal-insulator transition in the spectral regions 700–5500 and 9000–40 000 cm−1 have been studied in polarized light at 300 K. A comparisonis made between the spectra obtained and the corresponding spectra
of related isostructural conductors based on the ET molecule, and also the properties of the crystal structure of the investigated
compounds. An electronic transition between the ET molecules of the dimer (ET)
2
+
in the spectral region 700–5500 cm−1 has been identified, as have the features of the electronic-vibrational structure arising as a consequence of the interaction
of this transition with the completely symmetric intramolecular vibrations of the ET molecule. It is found that the conductor
with the stronger dimer interaction between the ET molecules has the higher the transition temperature.
Fiz. Tverd. Tela (St. Petersburg) 39, 1313–1319 (August 1997) 相似文献
19.
G. N. Sinyakov A. M. Shul'ga I. V. Filatov K. Dziliński N. V. Ivashin S. N. Terekhov V. S. Chirvonyi 《Journal of Applied Spectroscopy》1999,66(4):528-532
We present a brief review of the results of an investigation into the electronic structure of π- and M-anions of tetrapyrrole
compounds by the methods of molecular spectroscopy, namely, of electronic absorption and picosecond spectroscopy and also
of IR, RRS-, EPR-, NMR1N- and NMR13S-spectroscopy. Experimental data are compared with the results of quantum-chemical calculations.
Reported at the VIIIth International Conference on Spectroscopy of Porphyrins and Their Analogs, Minsk, September 22–26, 1998.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 4, pp. 488–491, July–August, 1999. 相似文献
20.
A.-H. Li Z.-R. Zheng T.-Q. Lü L. Sun W.-L. Liu W.-Z. Wu 《Applied physics. B, Lasers and optics》2010,98(1):149-158
Four near-stoichiometric lithium niobate (NSLN) crystals codoped with Er3+ (1 mol%) and MgO (0, 0.5, 1.0, and 2.0 mol%) were grown from K2O-based flux in air using top seeded solution growth technique. The [Li]/[Nb] ratio, estimated from the blueshift of ultraviolet
absorption edge, is 97.2% in NSLN:Er. MgO; codoping can increase the segregation coefficient of Er3+ in NSLN:Er:MgO crystal. The photorefractive damage threshold is enhanced by three orders of magnitude for NSLN:Er codoped
with 1 mol% MgO, it coincides with the peak shift of OH− absorption spectrum from 3481 to 3535 cm−1. Judd–Ofelt theory based on absorption spectra is used to analyze the influence of MgO concentration on the Judd–Ofelt intensity
parameter, transition strength, fluorescence branching ratio, and stimulated emission cross section. From the time-resolved
emission spectra and the comparison among emission spectra, two Er3+ crystal-field sites are ascertained in NSLN:Er codoped with 2 mol% MgO, this coincides with the bimodal structure in X-ray
photoelectron spectrometry spectra. The upconversion processes under pulse excitation is proposed based on the pump energy
dependence and decay kinetics. The distribution of Er3+-clustered sites in NSLN:Er:MgO series is discussed based on the nonexponential decay curves monitored at 550 nm under two-photon
excitation. 相似文献