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1.
We have carried out experimental and theoretical
studies on electron scattering from the C3H6 isomers and
C3F6 molecules and we report on total, differential as well
as theoretical integral elastic cross-sections for these
molecules. Vibrational excitation functions are also presented for
the typical vibrational peaks in C3H6 and cyclo-C3H6
for the angle of 90○, impact energy range of 1–16 eV
and loss energies of 0.12 eV and 0.13 eV, respectively. In the
cross-sections, clear differences in peak positions and magnitudes
between the C3H6 isomers can be viewed as the isomer effect.
The same is observed between C3H6 and C3F6 in a clear
manifestation of the fluorination effect. The resemblance of the
π* shape resonance in the cross-sections, observed at about
2.2 eV for C3H6 and 3.5 eV for C3F6, to those in
C2H4 and C2F4 clearly points to the effect of the
double bond in the molecular structures for these molecules.
Theoretical analysis is performed to provide rationales for the
scattering dynamics. 相似文献
2.
Excitation of H+, H2
+, H3
+, He+, and Ar+ ions by
impact on graphite and Al2O3 was investigated by means of emission
spectroscopy in the 50–1000 eV energy range of the projectiles.
Emission of Balmer series from excited neutral hydrogen is
observed for both targets. In addition, for the Al2O3 target
a continuum emission is observed. The continuum probably originates
from excited MnOm molecules produced in the collision cascade, when
surface atoms bound by ionic bonds are released after the bond breaking
caused by neutralization. The spectra obtained under Ar+ -bombardment
show Ar II lines emitted by backscattered ions. 相似文献
3.
R. B. Morgunov F. B. Mushenok S. M. Aldoshin N. A. Sanina 《Journal of Experimental and Theoretical Physics》2009,109(4):667-675
The effect of irradiation by ultraviolet light on the effective magnetic moment of a paramagnetic single crystal based on
photochrome spiropyran (Sp) and chromium oxalates Sp3Cr(C2O4)3 molecules is detected. It is shown that the deviation of the temperature dependence of the magnetic moment from the Curie
law is caused not by the exchange interaction, but by electron redistribution between Cr3+ and Cr4+ ions and spiropyran molecules Sp0 and Sp+. Analysis of the angular dependence of EPR spectra makes it possible to determine the contribution of Cr3+ ions to the magnetic properties of the crystals and to determine the crystal field parameters D = 0.619 cm−1 and E = 0.024 cm−1. Irradiation of hydrated samples by ultraviolet light leads to intensity redistribution of EPR lines attributed to Cr3+ and Sp0. Thermally stimulated paramagnetism of triplet states of spiropyran ions Sp+ and the SpI salt is observed. 相似文献
4.
The EPR spectra for VO2+ in CaO-Al2O3-SiO2 system are calculated using complete diagonalization method (CDM) and perturbation theory method (PTM). The calculated results
are in good agreement with the observed values. By comparing the calculated results by CDM and PTM in a wide range of crystal
field parameters, the validity of the PTM formulas has been studied. It is shown that, the PTM formulas are reasonable and
reliable in a wide range of CF parameters. 相似文献
5.
R. Piramidowicz R. Mahiou P. Boutinaud M. Malinowski 《Applied physics. B, Lasers and optics》2011,104(4):873-881
We report the orange-to-blue and infrared-(IR)-to-blue wavelengths upconversion luminescence in Pr3+:BaY2F8 crystals. Mechanism of the orange light upconversion into blue 3P0 state emission was confirmed to be energy transfer between two Pr3+ ions in the 1D2 state. IR-to-blue upconversion has only been observed under two different color IR pumping. The first resonant step was the
3H4→1G4 ground state absorption transition, and the second resonant transition was the excited state absorption from the 1G4 to 1I6 and 3PJ levels. A comparison of the efficiency of the IR-to-blue upconversion in several praseodymium activated host is presented
and discussed. A model of the IR pumped upconversion praseodymium blue laser is presented and the population inversion conditions
are calculated. 相似文献
6.
O. V. Ovchinnikov E. A. Kosyakova M. S. Smirnov A. B. Evlev V. G. Klyuev A. N. Latyshev A. N. Utekhin 《Journal of Applied Spectroscopy》2007,74(5):681-686
For microcrystals of Zn0.6Cd0.4S with adsorbed molecules of a number of organic dyes, we have observed sensitized anti-Stokes luminescence excited by radiation
with wavelengths in the range 610–750 nm and flux density 1014–1015 photons/cm2·sec. The positions of the bands in the excitation spectra for such luminescence match those of the absorption spectra for
the adsorbed dye molecules, which is evidence in favor of a cooperative mechanism for its appearance. We have shown that enhancement
of the anti-Stokes luminescence is possible when silver atoms and few-atom clusters appear on the Zn0.6Cd0.4S surface in addition to the dye molecules. We hypothesize that its excitation in the latter case occurs as a result of two-photon
optical transitions. These transitions occur sequentially, with transfer of an electron or the electronic excitation energy
from the dye molecules to silver atoms and few-atom clusters adsorbed on the surface of Zn0.6Cd0.4S, creating deep localized states in the bandgap with photoionization energies 1.80–2.00 eV.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 617–621, September–October, 2007. 相似文献
7.
G. A. Komandin A. S. Prokhorov V. I. Torgashev E. S. Zhukova B. P. Gorshunov A. A. Bush 《Physics of the Solid State》2011,53(4):736-744
The spectra of complex permittivity of a Ba2Mg2Fe12O22 single crystal belonging to the family of Y-type hexaferrites have been measured over a wide temperature range (10–300 K) with the aim of determining the dynamic parameters
of the phonon and magnetic subsystems in the terahertz and infrared frequency ranges (3–4500 cm−1). A factor-group analysis of the vibrational modes has been performed, and the results obtained have been compared with the
experimentally observed resonances. The oscillator parameters of all nineteen phonon modes of E
u
symmetry, which are allowed by the symmetry of the Ba2Mg2Fe12O22 crystal lattice, have been calculated. It has been found that, at temperatures below 195 and 50 K, the spectral response
exhibits new absorption lines due to magnetic excitations. 相似文献
8.
It is shown that, contrary to all previously studied systems, heating to ~800 K in the C60? TaS2 monolayer-Ta(100) adsorption system leads to the complete removal of the deposited fullerene molecules. A model is proposed that explains the observed phenomenon by a very weak nonchemisorption interaction between the C60 molecules and the valence-saturated surface of tantalum disulfide that forms layered crystals with van der Waals interaction between layers. 相似文献
9.
Three different photomagnetic effects caused by ultraviolet light in paramagnetic crystals based on molecules of spiropyrans
(Sp) Sp3Cr(C2O4)3 and SpI have been revealed and separated: (1) in the high-temperature range (30–300 K), the photomagnetic effect in Sp3Cr(C2O4)3 is determined by the charge transfer between chromium ions and spiropyran molecules; (2) in the low-temperature range (2
K), the photomagnetic effect in Sp3Cr(C2O4)3 is due to the photoisomerization of spiropyran molecules, the change in the crystal field, and the splitting of the levels
of Cr3+ ions in zero field; and (3) in the temperature range 2–20 K, the generation of radiation-induced paramagnetic defects contributes
to the magnetic moment of the organic sublattice Sp+. 相似文献
10.
V. F. Elesin N. N. Degtyarenko N. V. Matveev A. I. Podlivaev L. A. Openov 《Journal of Experimental and Theoretical Physics》2005,101(1):44-55
The existence of a metastable cluster He 4 * with total spin S = 2 is predicted. The cluster consists of two covalently bound excited spin-polarized triplet He 2 * molecules and is rectangular in shape. The electron wavefunctions, the dependence of the energy He 4 * system on the distance between the He 2 * triplet molecules, the atomic spacing, the frequency spectrum of natural oscillations of the cluster, and other characteristics are calculated from first principles. It is shown that the metastable state is formed if one of the excited He 2 * molecules is in the 3Σ u + state, while the other is in the 3Πg state. The radiation lifetime τ of the metastable cluster He 4 * is calculated; it is found to range from 100 to 200 s, which is much longer than the lifetime τ ≈ 20 s of the triplet molecule He 2 * (3Σ u + ). The height U ≈ 0.5 eV of the potential barrier preventing the departure from the local energy minimum is determined. The energy Eacc ≈ 9 eV/atom accumulated in the He 4 * cluster is calculated; this energy considerably exceeds the energy of known chemical energy carriers. It is shown that the accumulated energy is released virtually completely during decomposition of the He 4 * cluster into individual helium atoms. This means that helium clusters are a promising material with a high accumulated energy density (HEDM). 相似文献
11.
An anomalously high efficiency of generating Xe2I* excimer molecules in dense Xe–C3F7I gaseous mixtures with a small amount of C3F7I that are excited by a pulsed beam of fast electrons is discovered. The electron energy is 150 keV, and the beam current amplitude and duration are, respectively, 5 A and 5 ns. The temporal–spectral characteristics of spontaneous radiation from XeI* and Xe2I* excimer molecules are measured. Also, the luminescence times of the upper level for the B–X transition in the XeI* molecule (λmax = 253 nm) and the upper level for the 42Γ–12Γ transition in the Xe2I* molecule (λ = 352 nm), as well as the rate constants of quenching these levels by the gaseous mixture components, are determined. Based on the characteristics of the track structure of a high-energy plasma produced by charged particles in the dense gaseous medium, a model of plasma-chemical processes leading to the formation of XeI* (λmax = 253 nm) and Xe2I* (λ = 352 nmnm) excimer molecules in a Xe–C3F7I mixture with a small amount of an iodine atom donor is suggested. 相似文献
12.
M. A. Buldakov B. V. Korolev I. I. Matrosov V. N. Cherepanov 《Optics and Spectroscopy》2003,94(2):185-190
In the context of the Silberstein theory, by introducing model atoms, the polarizability of pairs of interacting molecules N2-N2, O2-O2, and N2-O2 was studied in relation to the mutual orientation and the intermolecular distance of the molecules in the pairs. The polarizability tensor for the equilibrium configurations of the (N2)2 and (O2)2 dimers was calculated. 相似文献
13.
High-frequency electron paramagnetic resonance (EPR) spectra of the KPb2Cl5:Tb3+ crystal have been investigated. Three types of spectra were observed in the frequency range of 74–200 GHz. The most intensive
spectrum with the resolved hyperfine structure corresponded to transitions between sublevels of the159Tb3+ ground quasi-doublet with the zero-field splitting (ZFS) close to 48 GHz. Experimental results were analyzed by the exchange
charge model of the crystal field affecting terbium ions in low-symmetry Pb2+ positions with the chlorine sevenfold coordination and the charge compensating vacancy in the nearest potassium site. The
calculated values ofg-factors and ZFS were in agreement with the experimental data. The nature of a broad EPR line with ZFS of about 180 GHz and
of additional weak EPR lines observed as satellites of the main Tb3+ lines was discussed. 相似文献
14.
The ionic conduction properties of undoped and doped Tl4HgI6 were investigated using electrical conductivity, dielectrics, differential scanning calorimetry, and X-ray diffraction techniques.
The heavy Tl+-ions diffusion was activated at high temperature, whereas low conductivity at the lower temperature suggested electronic
contribution in undoped Tl4HgI6. The partial replacement of heavy Tl+ ion by suitable cations (Ag+ and Cu+) enhanced the conductivity by several orders of magnitude, whereas diminution in conductivity results with increasing dopants’
concentration in Tl4HgI6. These results can be interpreted in terms of a lattice contraction and vacancy–vacancy interaction (leading to the cluster
formation), respectively. The dielectric values of undoped Tl4HgI6 system gradually increasing with temperature, followed by a sharp change, were observed around 385 K and can be explained
on the basis of increasing number of space charge polarization and ions jump orientation effects. The activation energy of
undoped and doped Tl4HgI6 systems were calculated, and it was found that ionic conductivity activation energy for 5 mol% of cation dopants is much
lower than that of undoped one, and also 10 mol% doped Tl4HgI6 systems. 相似文献
15.
We have studied spectral and amplitude-time characteristics of the emission by nitrogen, air, and the N2-CH4 mixture upon excitation by nanosecond and microsecond high-voltage discharge pulses in an inhomogeneous electric field in
the pressure range of 0.01–3 atm. In the pulsed and pulse-periodic discharge regimes, we have observed emission bands of the
violet system of cyan, the transition B
2Σ+ → X
2Σ+, which were comparable in intensity with bands of the (2+) system of nitrogen. We show that, in the pulsed regime, the highest intensity of the violet system of cyan is observed in
the N2-CH4 mixture. We show that, in the pulse-periodic discharge in nitrogen with a small amount of a carbon-containing admixture,
upon contracting the discharge, the efficiencies of formation and emission of the violet system of cyan considerably increase.
We confirm that admixtures of oxygen to nitrogen lead to suppression of the emission of the violet system of cyan molecules. 相似文献
16.
K. I. Arshinov M. K. Arshinov V. V. Nevdakh M.-Y. Perrin A. Soufiani V. V. Yasnov 《Journal of Applied Spectroscopy》2007,74(6):903-909
We present the results of analysis of the errors introduced by hot-band transitions 1110-0111, 0310-0111, 1200-1201 of the CO2 molecule and the absorption lines of the H2O and NO2 molecules in determination of the temperature and partial pressure of CO2, included in the gas mixture CO2: N2:H2O: NO2 at atmospheric pressure, by multiple-frequency laser probing using a CO2 laser tunable over the lines of the 0001-[1000,0200]I,II ground-state laser transitions.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 6, pp. 810–815, November–December, 2007. 相似文献
17.
C. Wesenberg O. Autzen E. Hasselbrink 《Applied Physics A: Materials Science & Processing》2007,88(3):559-569
The photochemistry of SO2 on thin epitaxial Ag films (5–60 nm) deposited on Si(100) has been studied using laser light with the wavelengths of 266,
355, and 532 nm. SO2 desorbs with cross sections of 1.7×10-19,1.7×10-20 and 2.9×10-21 cm2, respectively. The average translation energy, 〈Etrans/2k〉, is 440 K for 266 and 355 nm light, and 270 K for 532 nm light. Cross sections for a 60 nm thick Ag film are practically
identical to the ones for Ag(111) as the substrate. An increase by a factor of ∼3.5 is observed when the film thickness is
reduced to 5 nm for 266 and 355 nm light. No significant change is observed for 532 nm excitation. The film thickness has
no significant influence on the translational energy of the photodesorbed molecules. The data are discussed in connection
with the change of absorptivity of the metal film–semiconductor system. A model is put forward which takes into account the
light absorption in the Si substrate and the reduced relaxation of excited electrons in Si. Modelling indicates that electrons
excited in the Si substrate with energies and parallel momenta not allowed in Ag contribute to the surface chemistry after
crossing the gap in the projected band structure of Ag(111).
PACS 82.45.MP; 73.63.-b; 82.50.Bc 相似文献
18.
The sample of Mg0. 5+y (Zr1-y Fey) 2 (PO4) 3 (0.0 ≤y ≤0.5) was synthesized using the sol-gel method. The structures of the samples were investigated using X-ray diffraction and Fourier transform infrared spectroscopy measurement. XRD studies showed that samples had a monoclinic structure which was iso-structured with the parent compound, Mg0.5Zr (PO4) 3. The complex impedance spectroscopy was carried out in the frequency range 1–6 MHz and temperature range 303 to 773 K to study the electrical properties of the electrolytes. The substitutions of Fe3+ with Zr4+ in the Mg0.5Zr (PO4) 3 structure was introduced as an extrainterstitial Mg2+ ion in the modified structured. The compound of Mg0.5+y (Zr1-y Fey)2(PO4)3 with y?=?0.4 gives a maximum conductivity value of 1.25?×?10?5 S cm?1 at room temperature and 7.18?×?10?5 S cm?1 at 773 K. Charge carrier concentration, mobile ion concentration, and ion hopping rate are calculated by fitting the conductance spectra to power law variation, σ ac (ω)?=?σ o ? +?Aω α . The charge carrier concentration and mobile ion concentration increases with increase of Fe3+ inclusion. This implies the increase in conductivity of the compounds was due to extra interstitial Mg2+ ions. 相似文献
19.
V. F. Elesin N. N. Degtyarenko K. S. Pazhitnykh N. V. Matveev 《Russian Physics Journal》2009,52(11):1224-1234
Within the framework of multi-configurational self-consistent field (MCSCF) approximation, the ground and excited states of
the N4(D2H) cluster of N2 molecules are modeled from different initial states. The potential barriers to the cluster formation and dissociation are
calculated. Investigations of the N4(D2H) electronic spectrum demonstrate that the most promising method of forming nitrogen nanostructures is compression of the
excited triplet N2 molecules. 相似文献
20.
T. Hoger D. Grimmer H. Zacharias 《Applied Physics A: Materials Science & Processing》2007,88(3):449-458
The desorption of NO from a well-characterized, epitaxially grown semiconducting C60 surface is reported. Two different channels are identified in the laser desorption. Both channels yield a comparably high
desorption cross section of σ1=7.0×10-17 cm2 and σ2=5.5×10-17 cm2 for the first and second channel, respectively. The laser desorbed NO molecules are detected with rovibrational state selectivity
by (1+1) REMPI in the -bands. In the first channel the desorbing molecules are highly excited with an average kinetic energy of 〈Ekin〉=174 meV. The rotational population distribution can be fitted by a rotational temperature of Trot=800 K. A rotational–translational coupling is observed, with velocities ranging from 1000 m/s for low to 1300 m/s for high
rotational states. The vibrationally excited population is estimated to be less than 1% of the ground state. The second channel
yields less excited molecules and an almost Boltzmann distributed rotational population with a temperature of Trot=280 K. The apparent velocity distribution derived from the pump-probe delay yields molecules much too slow to be explained
by even a thermal desorption. This desorption is probably caused by a long-lived electronic excitation in the substrate for
which a lifetime of τ≈160 μs is estimated.
PACS 42.62.Fi; 34.50.Dy; 68.49.Df; 68.43.Tj; 79.20.La 相似文献