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1.
Abstract

Optical absorption spectrum of cobalt doped MgNH4PO4 · 6H2O (struvite) is investigated in UV-VIS-NIR regions. The spectrum in UV-VIS-NIR region is attributed to Co2+ in octahedral symmetry whereas the IR spectrum is attributed to vibrations due to PO4 3-, NH4 + and H2O. The following crystal field (Dq) and interelectronic repulsion (B, C) parameters are evaluated: Dq = 940cm?1, B = 870cm?1 and C = 3970cm?1.  相似文献   

2.
ABSTRACT

Crystal field absorption and emission spectra originated by 5I8 ? 5F5 transitions, due to Ho3+ (1% molar fraction) in a YPO4 single crystal, were investigated in the 15000 to 16000 cm?1 range. Fourier Transform high resolution absorption measurements, performed in the 9 to 300 K range, and photoluminescence, monitored at 10 K upon 540 nm excitation, supplied the sublevel separations within both 5I8 and 5F5 manifolds. The sublevel positions were compared to those calculated by diagonalization of the full 4f-configuration matrix in the framework of a single-ion model. The results are discussed also in relation with experimental data previously reported for similar systems containing Ho3+.  相似文献   

3.
Abstract

Three new bands of the B 2Σ+X 2Σ+ system of 12C17O+ have been investigated using conventional spectroscopic techniques. The spectra were observed in a graphite hollow‐cathode lamp by discharging molecular oxygen (enriched in about 45% of the 17O2 isotope) under 1.0 Torr pressure. The rotational analysis of the 2–4, 2–5, and 2–6 bands was performed with the effective Hamiltonian of Brown (Brown et al., J. Mol. Spectrosc. 1979; 74: 294–318). Molecular constants were derived from a merge calculation, including both the current wavenumbers and the spectroscopic data published by the authors previously. The principal equilibrium constants for the ground state of 12C17O+ are ωe=2185.9658(84), ωe x e = 14.7674(11), B e=1.927001(38), αe=1.8236(22)×10?2, γe=?0.331(28)×10?4, D e=6.041(12)×10?6, βe=0.100(31)×10?7 cm?1, and the equilibrium constants for the excited state are σe=45876.499(15), ωe=1712.201(12), ωe x e=27.3528(39), B e=1.754109(35), αe=2.8706(57)×10?2, γe = ?1.15(19)×10?4, D e=7.491(20)×10?6, βe=2.13(12)×10?7, γe = 2.0953(97)×10?2, and αγe=?9.46(59)×10?4 cm?1, respectively. Rydberg–Klein–Rees potential energy curves were constructed for the B 2Σ+ and X 2Σ+ states of this molecule, and Franck–Condon factors were calculated for the vibrational bands of the BX system.  相似文献   

4.
Abstract

On radiolysis tris(acetylacetonato) cobalt(III) in aqueous solutions is found to get reduced by reaction with (1) hydrated electrons, (2) H atoms, (3) OH radicals and (4) C2H2OH radicals. The bimolecular rate constants for the first three reactions, determined by competition kinetics are: 4 × 1010, 2.3 × 109 and 4.7 × 109 M?1sec?1 respectively. Absorption spectra of the irradiated solutions indicate the formation of bis(acetylacetonato) cobalt(II) from reaction (1), but not from (3). The total cobaltous yield in air-free solutions is given byG(Co++) = 5.6 and 6.5 at pH 6.5 and 1 respectively. It appears that Geaq- ∽ H + GoH ∽ 2.8 in neutral solutions. Considerations of material balance for the primary yields of radiolysis of water suggest the possibility that the so-called independent H-atoms in neutral solutions are probably excited water molecules or ion-pairs.  相似文献   

5.
ESR studies were conducted on Cu2+-doped bis-(5,5′-diethylbarbiturato)bis picoline Zn(II). Two Cu2+ lattice sites, Cu2+(I) and Cu2+(II), were identified. These sites exhibit two sets of four hyperfine lines in all directions. The g factor and hyperfine splitting were calculated from ESR absorption spectra: gx ?=?2.0201?±?0.002, gy ?=?2.0900?±?0.002, gz ?=?2.1634?±?0.002, Ax ?=?(30?±?2)?×?10?4?cm?1, Ay ?=?(40?±?2)?×?10?4?cm?1 and Az ?=?(154?±?2)?×?10?4?cm?1. It was found that Cu2+ enters the lattice substitutionally. The ground-state wavefunction of the Cu2+ ion in this lattice was determined from the spin Hamiltonian constants obtained from the ESR studies. With the help of an optical absorption study, the nature of the bonding in the complex is also discussed.  相似文献   

6.
ABSTRACT

High-resolution emission spectrum of the 1–4 band of the B 2Σ+X 2Σ+ transition of 14C16O+ was observed for the first time by conventional emission spectroscopy. The band spectrum was excited in a water-cooled Geissler lamp filled with commercial gaseous carbon monoxide enriched in about 80% of the radiocarbon 14C. A rotational analysis has been carried out and obtained molecular constants have been merged with previously published data for the B 2Σ+A 2Πi and A 2ΠiX 2Σ+ transitions. The principal equilibrium constants for the ground X 2Σ+ state obtained from this work are ωe = 2121.7726(98), ωe x e = 13.9055(27), B e = 1.815290(30), αe = 1.6594(33) × 10?2, and γe = ? 0.377(73) × 10?4 cm?1. Also, presently known experimental equilibrium molecular constants of the X 2Σ+ states of the CO+ isotopic molecules are summarized and isotopic dependence of the B e and ω e constants is discussed.  相似文献   

7.
This paper reports the spectral properties and energy levels of Cr3+:Sc2(MoO4)3 crystal. The crystal field strength Dq, Racah parameter B and C were calculated to be 1408 cm−1, 608 cm−1 and 3054 cm−1, respectively. The absorption cross sections σα of 4A24T1 and 4A24T2 transitions were 3.74×10−19 cm2 at 499 nm and 3.21×10−19 cm2 at 710 nm, respectively. The emission cross section σe was 375×10−20 cm2 at 880 nm. Cr3+:Sc2(MoO4)3 crystal has a broad emission band with a broad FWHM of 176 nm (2179 cm−1). Therefore, Cr3+:Sc2(MoO4)3 crystal may be regarded as a potential tunable laser gain medium.  相似文献   

8.
Attempts were made to grow CeO2 and ThO2 single crystals doped with transition metal ions. Only Fe3+ and Mn2+ could be detected by the EPR technique. The EPR spectrum of Fe3+ in CeO2 exhibits the well-known fine structure in cubic fields. The parameters areg=2.0044(1) anda=15.6(1)·10?4 cm?1. The hyperfine constantA for57Fe in hexahedral coordination was found to be 8.9(1)·10?4 cm?1. The EPR spectrum of Mn2+ in CeO2 reveals two cubic Mn2+ centers. The parameters for center 1 areg=1.9999(1) andA=86.9(1)·10?4 cm?1 and for center 2g=1.9984(1) andA=87.0(1)·10?4 cm?1. Heating the Mn doped CeO2 samples in hydrogen, the Mn2+ centers transform from cubic into trigonal centers with approximate values ofg=1.9988(2),A=84.5(6)·10?4 cm?1 andD=203(1)·10?4 cm?1. The two observed Mn2+ centers in ThO2 exhibita priori axial symmetry with approximate values ofg=2.0006(2),A=88.9(4)·10?4 cm?1 andD=33(3)·10?4 cm?1.  相似文献   

9.
Abstract

o ?, m ? and p ? aminobenzoic acid hydrazide (ABAH) complexes with (NH4)2 Fe (So4)2 and Fe Cl3 were prepared with the type [ML2.2H2O] X. where X = Cl3 or SO4. The prepared complexes were investigated using IR, electronic and Mossbauer spectroscopes. The obtained results indicated that the iron ions are present in octahedrally coordinated Fe2+, and Fe3+ states.

Also the results reveal that all the complexes contain keto form, except m ? ABAH Fe (II) complex which contains enol form in addition to the keto form.  相似文献   

10.
A Cu2+-doped single crystal of catena-trans-bis(N-(2-hydroxyethyl)-ethylenediamine) zinc(II)-tetra-m-cyanopaladate(II) [ZnPd(CN)4(C4H12N2O2)] complex has been investigated by electron paramagnetic resonance (EPR) technique at room temperature. EPR spectra indicate that Cu2+ ions substitute for magnetically equivalent Zn2+ ions and form octahedral complexes in [ZnPd(CN)4(C4H12N2O2)] hosts. The crystal field affecting the Cu2+ ion is nearly axial. The optical absorption studies show two bands at 322 nm (30864 cm−1) and 634 nm (15337 cm−1) which confirm the axial symmetry. The spin Hamiltonian parameters and the relevant wave function are determined.  相似文献   

11.
The v4 fundamental band of CF379Br and CF381Br, present in natural isotopic abundance, was investigated in the 8.3-μm region by high-resolution infrared spectroscopic techniques. Tuneable diode laser spectra were recorded in the ranges 1202.5–1205.0 cm?1, 1208.0–1210.1 cm?1 and 1212.5–1214.5 cm?1. The tuneable diode laser spectra were obtained at the reduced temperature of 200 K and in a free-jet expansion. The latter technique was used to reduce spectral congestion, achieving a rotational temperature of about 50 K, with a resolution up to 0.0008 cm?1. A Fourier transform infrared spectrum covering the entire spectral region of the v4 band, between 1190 and 1220 cm?1, was recorded at 298 K with a resolution of 0.004 cm?1. The experimental wavenumbers from the different spectroscopic techniques were combined to accomplish the complete ro-vibrational analysis of v4. In total, 4651 transitions were assigned to CF379Br, 4047 to CF381Br, with Jmax? = Kmax?=80; of these, 3171 for CF379Br and 2755 for CF381Br are from diode laser measurements. The data of each isotopologue were analysed using the model Hamiltonian for a degenerate vibrational state of a molecule of C3v symmetry. The v4 band of both the isotopologues resulted essentially unperturbed, but the Δl = Δk = ±2 l-resonance was found to be active within the v4 = 1 state. Precise values of the vibrational energy and of the ro-vibrational parameters of v4 = 1 for CF379Br and CF381Br were obtained. The bromine isotopic splitting amounts to 6.9 × 10?3 cm?1. In addition, the equilibrium geometry and the harmonic force field were calculated ab initio using the large-size basis set def2-QZVP in conjunction to the PBE0 functional.  相似文献   

12.
ABSTRACT

A new multielement sensitive fluorescent probe, 1-(2-(phenylthio)ethyl)-2-(pyridin-2-yl)-1H-benzo[d]imidazole (L), has been synthesized by the reaction between 2-(pyridyl) benzimidazole and 2-chloroethyl phenyl sulfide. Excitation and emission wavelength of L are at 330 and 371 nm, respectively. Among various transition and nontransition metal ions, it can selectively read Zn2+ ion as the emission wavelength of L undergoes a red shift by 31 nm upon binding with Zn2+ in methanol. In the presence of Cd2+, Hg2+, and other common cations, the emission wavelength of L remains unchanged, and thus allows us to discriminate Zn2+ from its congeners. Both L and its Zn2+ complex are well characterized by different spectroscopic techniques like 1H-NMR, ESI-TOF (+) mass, FT-IR, and elemental analysis data. The binding constant value of the complexation reaction between L and Zn2+ is found as 724.6 M?1 in methanol. Density functional theoretical (DFT) studies nicely demonstrate the red shift in the emission wavelength of L upon binding with Zn2+.  相似文献   

13.
Abstract

Salts of the [Eu(2,6-pyridinedicarboxylate)3]3- complex anion and various monovalent inorganic and organic counterions (Li+, Na+, K+, Rb+, Cs+, NH4 +, and pyridinium+) have been synthesized and studied by emission spectroscopy. The Eu3+ ion emission spectra exhibited by these salts have been observed with high resolution (less than 1.0 cm?1) and at low temperature (77 K). The emission spectra of these compounds indicate that changing the attached counterion does not affect the site symmetry observed by the europium ion beyond slight distortions indicated by small shifts in the energies of the Eu3+ electronic levels.  相似文献   

14.
The EPR spectrum of the non-Kramers iron ion Fe4+ (S=2) in a KTaO3:Fe crystal appearing after illumination of the sample in the visible has been detected and studied. Because of the large initial splitting (|D|=4.15 cm−1), only transitions within the |±1〈 and |±2〈 doublets are seen experimentally. Superhyperfine structure in the spectrum of a non-Kramers ion in perovskites has been detected for the first time. A structure is proposed for the center responsible for the new EPR spectrum, which represents a complex of a Fe4+ ion substituting for Ta with an oxygen vacancy at the nearest anion site. Fiz. Tverd. Tela (St. Petersburg) 41, 1424–1427 (August 1999)  相似文献   

15.
高有辉 《中国物理 B》2011,20(10):107502-107502
Exchange-spring magnet L1-FePt/(Fe2B+α-Fe) is fabricated by flash annealing a melt-spun Fe48Pt34B34 foil. A coercivity of 8500 Oe (1 Oe = 79.5775 A/m), squareness (Mr/Ms) of 0.70, saturation magnetization of 10.2 kGs (1 Gs = 10-4 T) and an effective anisotropy Keff =2.0 × 107 ergs/cm3 are obtained. A two-step magnetization reversal feature is characterized in this paper. An exchange bias phenomenon is also observed in a low saturation field.  相似文献   

16.
The local lattice distortions and the electron paramagnetic resonance (EPR) parameters (g factors, hyperfine structure constants and zero-field splittings) for Cu2+, Mn2+ and Fe3+ in ZnWO4 are theoretically studied based on the perturbation calculations for rhombically elongated octahedral 3d9 and 3d5 complexes. The impurity centres on Zn2+ sites undergo the local elongations of 0.01, 0.002 and 0.013 Å along the C2 axis and the planar bond angle variations of 8.1°, 8.0° and 8.6° for Cu2+, Mn2+ and Fe3+, respectively, due to the Jahn–Teller effect and size and charge mismatch. In contrast to the host Zn2+ site with obvious axial elongation (~0.31 Å) and perpendicular (angular) rhombic distortion, all the impurity centres demonstrate more regular octahedral due to the above local lattice distortions. The copper centre exhibits significant Jahn–Teller reductions for the spin-orbit coupling and orbital angular momentum interactions, characterised by the Jahn–Teller reduction factor J (≈0.29 ? 1). The calculated EPR parameters agree well with the experimental results. The local structures of the impurity centres are analysed in view of the corresponding lattice distortions.  相似文献   

17.
ABSTRACT

We present a theoretical study of the ground electronic state potential of the Ca+Ar2 complex and of its photoabsorption spectra, simulated at temperatures ranging between 20 and 220?K. These calculations exploit a Monte-Carlo (MC) method, based on a one-electron pseudo-potential approach. A pairwise additive potential fitted to coupled cluster ab initio points, is used to model the Ca+Ar2 complex. Our study shows that the most stable form of Ca+Ar2 is a bent C2v structure, whereas the linear isomer is located at around 90?±?10?cm?1 above in energy. The analysis of the photoabsorption spectra establishes that a structural transition from bent Ca+Ar2 to linear ArCa+Ar occurs at T~100?K. Trends in binding energies of both isomers, bond lengths and bond angles are also discussed. Molecular orbital overlaps provide an explanation for the order of stability between the bent and linear structures.  相似文献   

18.
Gd3+-substituted micro-octahedron composites (FexCo1−x/CoyGdzFe3−yzO4) in which the Fe-Co alloy has either a bcc or fcc structure and the oxide is a spinel phase were fabricated by the hydrothermal method. The X-ray diffraction (XRD) patterns indicate that the as-synthesized Gd3+-substituted micro-octahedron composites are well crystallized. Scanning electron microscopy (SEM) images show that the final product consists of larger numbers of micro-octahedrons with the size ranging from 1.3 to 5 μm, and the size of products are increased with increasing the concentration of KOH. The effect of the Co2+/Fe2+ ratio (0?Co2+/Fe2+?1) and substitution Fe3+ ions by Gd3+ ions on structure, magnetic properties of the micro-octahedrons composites were investigated, and a possible growth mechanism is suggested to explain the formation of micro-octahedrons composites. The magnetic properties of the structure show the maximal saturation magnetization (107 emu/g) and the maximal coercivity (1192 Oe) detected by a vibrating sample magnetometer.  相似文献   

19.
ABSTRACT

Polyimide (PI) films were irradiated by 120 MeV iron (Fe+9) ions and variations in its optical, chemical, surface morphology and anti-bacterial properties were studied. UV-Visible spectroscopic results showed the decrease in the optical band gap of PI after irradiation due to the chain scission mainly at the carbonyl group which is corroborated by Fourier Transform Infrared spectroscopic results. The scanning electron microscopic results showed the surface roughening, surface structure broken and micro-porous formation in PI after irradiation. These results are also corroborated by the decrease in contact angle as studied by the contact angle measurement. PI films irradiated by 120 MeV Fe+9 ions showed increased anti-biofilm efficacy against the human pathogen, Salmonella typhi. In addition to this, the morphological changes were also observed due to the stress of Fe-irradiated PI. Biofilm formation was inhibited ≈ 35% at 1?×?1011 ion/cm2 and 80% at 5?×?1012 ion/cm2 in irradiated PI films. Thus, surface modification of PI films help in the inhibition of biofilm formation.

Highlights
  1. Polyimide (PI) films were irradiated by 120?MeV Fe+9 ions.

  2. Optical band gap of PI decreased after ion irradiation.

  3. Surface roughening and micro-pores formation in PI after ion irradiation.

  4. Surface modification of PI films helps in the inhibition of bio-film formation.

  相似文献   

20.
Abstract

The infrared spectrum of 1:1 complex of mercury(II) saccharinate with 2,2′-bipyridine, [Hg(C7H4NO3S)2(C10H8N2)], was studied in the CO and SO2stretching regions. The appearance of the spectrum in the region of the carbonyl stretching modes was correlated with the number of non-equivalent CO groups in the structure. The spectral and structural characteristics of the CO groups in the title compound were compared with the corresponding ones in the mercury(II) saccharinate and chloromercury(II) saccharinate. It was found that the frequency of the CO stretchings in the spectrum of Hg(bpy) (sac)2 is significantly lower (1630 and 1615 cm?1) than the frequency of the corresponding modes in the spectra of covalently bonded mercury(II) saccharinate (1705 and 1680 cm?1) and chloromercury saccharinate (1694 cm?1). An attempt was also made to assign the bands which are mainly due to the symmetric and the antisymmetric SO2 stretching vibrations.

  相似文献   

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