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1.
The magnetic phase diagram of Ni(NO3)26NH3 was determined from the field and temperature dependence of the magnetic susceptibility. The zero temperature exchange and anisotropy fields were determined to be HE(0) ≈ 26 kOe and HA(0) ≈ 0.7 kOe respectively. 相似文献
2.
EPR measurements on crystals of compressed tetragonal Rb2PbCu(NO2)6 and K2PbCu(NO2)6 subjected to uniaxial stress have been carried out at various temperatures. The results indicate that uniaxial stress can reorient the crystal axes in both compounds and that smaller stresses are required for Rb2PbCu(NO2)6 than for K2PbCu(NO2)6 at comparable temperatures. Larger stresses are required at lower temperatures. 相似文献
3.
Gang Luo 《Journal of Physics and Chemistry of Solids》2006,67(4):639-642
We present measurements of the paramagnetic susceptibilities of K3Pr2(NO3)9 and K3Sm2(NO3)9, cubic materials with rare earth sites having threefold rotational symmetry about (111). The rare earth environment resembles that of the Ln2Mg3(NO3)12·24H2O materials, and the magnetic susceptibilities show similarities but also interesting differences with Pr2Mg3(NO3)12·24H2O and Sm2Mg3(NO3)12·24H2O. Paramagnetic resonance experiments in K3La2(NO3)9 doped with these and several heavier lanthanides are also described and compared with theory. 相似文献
4.
M.F. Gerard N.M.C. Casado M. Perec R. Calvo 《Journal of Physics and Chemistry of Solids》2007,68(8):1533-1539
Magnetic and EPR data have been collected for complex [Cu(L-Arg)2](NO3)2·3H2O (Arg=arginine). Magnetic susceptibility χ in the temperature range 2-160 K, and a magnetization isotherm at T=2.29(1) K with magnetic fields between 0 and 9 T were measured. The observed variation of χT with T indicates predominant antiferromagnetic interactions between Cu(II) ions coupled in 1D chains along the b axis. Fitting a molecular field model to the susceptibility data allows to evaluate g=2.10(1) for the average g-factor and J=−0.42(6) cm−1 for the nearest neighbor exchange coupling (defined as Hex=-∑JijSi·Sj). This coupling is assigned to syn-anti equatorial-apical carboxylate bridges connecting Cu(II) ion neighbors at 5.682 Å, with a total bond length of 6.989 Å and is consistent with the magnetization isotherm results. It is discussed and compared with couplings observed in other compounds with similar exchange bridges. EPR spectra at 9.77 were obtained in powder samples and at 9.77 and at 34.1 GHz in the three orthogonal planes of single crystals. At both microwave frequencies, and for all magnetic field orientations a single signal arising from the collapse due to exchange interaction of resonances corresponding to two rotated Cu(II) sites is observed. From the EPR results the molecular g-tensors corresponding to the two copper sites in the unit cell were evaluated, allowing an estimated lower limit |J |>0.1 cm−1 for the exchange interaction between Cu(II) neighbors, consistent with the magnetic measurements. The observed angular variation of the line width is attributed to dipolar coupling between Cu(II) ions in the lattice. 相似文献
5.
The purpose of this paper is to investigate the interplay between the chemical shielding anisotropy and quadrupole interaction in MQMAS spectra.
in the compounds Na3Co(NO2)6 and trans-Co[(en2)(NO2)2]NO3 provides model systems for such an investigation. Furthermore, only few results have been reported on the application of the MQMAS method to a spin I=7/2. The possibilities of the MQMAS spectroscopy for determining the relative orientation of the two tensors and its advantage over previous techniques are discussed. Reported experimental spectra at different spinning speeds of Na3Co(NO2)6 are accurately reproduced by our theoretical simulations. The calculations are based on a recent approach, summarized in the present paper, which allows one to perform efficient simulations of MQMAS spectra including all interactions and their time-dependence throughout the experiment. This is necessary for calculating accurate MQMAS spectra including the spinning sideband pattern. In the case of trans-Co[(en2)(NO2)2]NO3 where the quadrupolar interaction and chemical shielding are stronger and their axes are non-coincident, the MQMAS spectrum is strongly distorted due to the unsufficient spinning speed and RF power. In this case, MAS at different spinning speeds is shown to provide valuable information. 相似文献
6.
Xie Lin-Hua Zhao Guo-Ping Qiu Min 《Journal of magnetism and magnetic materials》2010,322(15):2184-2186
In this work, a full ligand-field energy matrix (10×10) diagonalization treatment for 3d1 ions in tetragonal symmetry is developed on the basis of the two-s.o.-coupling-parameter model. Spin Hamiltonian parameters (g factors g∥, g⊥ and hyperfine structure constants A∥, A⊥) of the tetragonal V4+ center in Zn(antipyrine)2(NO3)2 are calculated from the complete energy matrix diagonalization method and the perturbation theory method. The calculated results from both methods are not only close to each other but also in good agreement with the experimental values. Furthermore, the compressed defect structure of V4+ center is discussed. 相似文献
7.
dc ionic conductivity measurements were made on single crystals of Pb(NO3)2 doped with monovalent Na+ and K+ in the temperature range of 100–400°C. In the extrinsic region the conductivity was found to decrease with Na+ having a smaller ionic size, and to increase with K+ with larger ionic size compared to the host Pb ion. Conductivity is attributed to the mobility of anti-Frenkel defects as in the case of PbF2. Dielectric loss measurements were made on the Pb(NO3)2: K+ system in the frequency range of 300 Hz to 20 kHz at different temperatures. Impurity vacancy pairs of the type K+-(NO-3)V are found to be responsible for the observed dielectric loss peaks. The maximum peak frequency is found to increase with temperature. 相似文献
8.
The conductivity σ of a microemulsion series consisting of CTAB + butanol + octane, in which a solution of Al(NO3)3 0.8 M + Zn(NO3)2 0.4 M was gradually added, was studied at room temperature as a function of its composition φ. The addition of nitrate salts solution took place in four different ratios of (butanol + CTAB):octane = 0.2, 0.4, 0.6 and 0.8. Initially, all those four systems are (water in oil, w/o) microemulsions and the gradual addition of the solution of the nitrate salts transforms them to bicontinuous ones. The conductivity increases gradually, but with different rate in each case, and the corresponding critical exponents at the percolation threshold were determined from the curves σ = f(φ). Next at three different compositions of microemulsions, corresponding to ratios (butanol + CTAB):octane = 0.4, 0.6 and 0.8 and ratio of the nitrate salts solution x ≈ 0.25, spinels ZnAl2O4 were isolated/prepared. XRD, SEM and N2 adsorption-desorption measurements were used to determine the structure and texture of those solids. From those measurements the surface area (Sp), the pore volume (Vp), the size of crystallites and the average pore connectivity (c) were found. Those properties showed considerable variation and dependence on the composition of the original microemulsions employed in the preparation, a fact indicating that the structure and texture of the obtained solids can be manipulated at will via the composition of microemulsion used. 相似文献
9.
We have determined the photophysical properties of [Eu(C12H8N2)2](NO3)3, (EuPhen), a complex which is very promising for photonic and optoelectronic applications, because of its easy synthetic procedure and high thermal stability (up to 300 °C) combined with large sensitization efficiency and good emission quantum yield. Available experimental absorption and emission data have been analyzed by using Judd-Ofelt analysis. Moreover, semi-empirical calculations have been used to determine the structure of the complex and to interpret the convoluted shape of the absorption spectrum. 相似文献
10.
Preparation and characterization of slice-like Cu2(OH)3NO3 superhydrophobic structure on copper foil
Superhydrophobic structure was prepared on copper foil via a facile solution-immersion method. Thus slice-like Cu2(OH)3NO3 crystal was prepared on the surface of the copper foil by sequential immersing in an aqueous solution of sodium hydroxide and cupric nitrate. And the superhydrophobic structure was obtained by modifying the slice-like Cu2(OH)3NO3 crystal with 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS-17). The morphologies, chemical compositions and states, and hydrophobicity of the surface-modifying films on the copper foil substrates were analyzed by means of scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and water contact angle measurement. Moreover, the thermal stability of the slice-like structure was also evaluated using thermogravimetric analysis (TGA). It was found that roughening of the copper foil surface helped to increase the hydrophobicity to some extent, but no superhydrophobicity was obtained unless the slice-like Cu2(OH)3NO3 crystal formed on the Cu substrate was modified with 1H,1H,2H,2H-perfluorodecyltriethoxysilane. Besides, the superhydrophobicity of the FAS-17-modified slice-like Cu2(OH)3NO3 structure was closely related to the surface morphology. And this hydrophobic structure retained good superhydrophobic stability at elevated temperature and in long-term storage as well, which should be critical to the application of Cu-matrix materials in engineering. 相似文献
11.
The magnetic susceptibility of the layered compounds (CH2)3(NH3)2FeCl2Br2 and (CH2)6(NH3)2FeCl2Br2 has been measured in the range 80 < T < 300 K. The results follow a Curie-Weiss behavior in the range 120 < T < 300 K but are field dependent for T < 120 K. The results are interpreted in terms of a two-dimensional antiferromagnetic interaction which is canted. A comparison with the corresponding pure chloride compounds is given. 相似文献
12.
以Nd:YAG激光器的二倍频输出光为抽运光,其三倍频输出抽运的光学参量发生/放大器输出光为探测光,利用光学-光学双色双共振多光子离化光谱技术(OODR-MPI),获得了NO2分子在605—675nm探测光波长范围内的多光子离化激发谱. 通过对NO2分子离化机理的分析,确定了在此波长区间,NO2分子经1+3+1双共振多光子过程离化,离化通道为NO2(X2A1)hν
关键词:
2')" href="#">NO2
光学-光学双共振多光子离化谱
里德伯态
分子常数 相似文献
13.
The mixed compound (CH3NH3)2Cu(Cl0.1Br0.9)4 which has random bonds of ferromagnetic and antiferromagnetic interactions has been investigated by the pulsed NMR of 1H, 63,65Cu and 79,81Br. The temperature dependence of the line width of 1H showed the existence of the magnetic phase transition at 15 K in the applied field of 4 kOe. The moments of Cu2+ have been shown to lie within the c-plane and have some randomness from the field dependence of the NMR spectrum and the spin-echo decay time of the copper and the bromine nuclei. 相似文献
14.
G. van Kalkeren R. Srinivasan C.P. Keijzers J.S. Wood E. de Boer 《Solid State Communications》1982,44(8):1285-1287
Semi-dilute 10% 63Cu : Zn(pyO)6(ClO4)2 [pyO = C5H5NO, pyridine-N-oxide] has been studied by EPR. Spectra of pairs of Cu(pyO)2+6 ions are observed below the transition from dynamic to static Jahn-Teller distortion. Most of these pairs are antiferrodistortively oriented. They exhibit only the type of exchange which corresponds to the interchain interaction J′ in the pure Cu compound. From the Q-band AB type of spectrum it was found that |J′|/k = 0.041 K. An estimate of the zero- point spin reduction could be derived (~36%). 相似文献
15.
S. Mørup 《Journal of Physics and Chemistry of Solids》1974,35(9):1159-1162
The ferric ions in Fe(NO3)3·9H2O are connected in pairs by a screw dyad axis. When a magnetic field is applied, two neighbouring ions may have different energy splittings unless the field is applied parallel or perpendicular to the screw dyad axis. As a flip-flop process on the whole must be energy conserving, the spin-spin relaxation time depends on the angle between the field and the screw dyad axis. This effect is demonstrated by Mössbauer effect measurements on single crystals of Fe(NO3)3·9H2O. 相似文献
16.
The Raman and infrared spectra of (CH3)2Cd and (CH3)2Zn have been reexamined and are reported along with previously unreported vibrational data for (CD3)2Cd and (CD3)3Zn. The spectra have been analyzed using the double group , which has led to some changes in assignments made previously. Comparison is also made with a recent study of (CH3)2Hg and (CD3)2Hg. Fine structure was observed for two of the vibrations of the E1d symmetry species, arising from internal rotation of the methyl groups. This structure has been analyzed using a recently developed theory for molecules of the freely rotating dimethylacetylene type. Problems which arise in the application of this theory have been pointed out, and it is suggested that some additional consideration of the theory may be necessary. 相似文献
17.
S. Mørup F. Sontheimer G. Ritter R. Zimmermann 《Journal of Physics and Chemistry of Solids》1978,39(2):123-128
The spin-spin relaxation of Fe3+ ions in Fe(NO3)3·9H2O single crystals has been studied at 4.2 K in the presence of external fields up to 80 kG. It is found that the spin-spin relaxation frequency varies substantially when the field direction is changed. Furthermore, the relaxation frequency increases with increasing applied field. Both effects are in agreement with the spin-spin relaxation theory of Bloembergen et al. 相似文献
18.
The heat capacity of K2PbCu(NO2)6 shows anomalies at 273K and 280K, which are accompanied by length changes. At 280 K a change in the E.S.R. spectrum is observed. 相似文献
19.
The action of the monovalent M+ cations on the luminescent properties of the mixed M
x
(1)
M
1-x
(2)
UO2(NO3)3 crystals, where M is Na, K, Rb, Cs, or NH4 , has been investigated. It has been established that the spectral positions of the bands of vibronic transitions depend linearly on the ratio between the concentrations of the M(10) and M(2) cations. It is shown that the crystals considered are composed of l[RbUO2(NO3)3]n[CsUO2(NO3)3] clusters, where l/n = x/(1 - x). The spectral regularities revealed are determined by the partial contributions of the M(1) and M(2) cations to their combined, polarizing action on the uranyl complex and are explained by the ligand nature of its highest occupied molecular orbital.Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 71, No. 6, pp. 827–830, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date. 相似文献
20.
The temperature dependence of elastic stiffnesses of K2Ba(NO2)4 is investigated in the range - 140 to + 160°C, in which two phase transitions have been reported. Marked anomalies appear at the lower transition, in contrast with continuous variations through the upper transition. Results are compared to those obtained near the upper transition by an ultrasonic method and they are qualitatively discussed. 相似文献