首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Cross sections for collision induced dissociation of 0.65 to 3.2 keV I+2(2Πg, υ) ions in I+2(2Πg, υ) + N2(X 1Σ+g, υ = 0) interactions have been determined. Reaction cross sections for I+2(2Π32,g, υ) ions in low vibrational levels vary smoothly from 6 to 10 A2 with increasing kinetic energy. Dissociation cross sections for I+2(2Π12,g, υ) ions are larger than those involving ground state ions. Processes involving highly excited metastable states of I+2 are not observed in this investigation.  相似文献   

2.
As a part of a systematic study of the synergic extractions of metals with mixtures of acidic chelating extractants and lipophilic anion-exchangers (B, X with X?6 inorganic anion), the extractions of M  Cd and Zn from perchlorate, nitrate and sulphate media with 1-phenyl-3-methyl-4-benzoyl-pyrazol-5- one (HL) and tri-n-octylammonium salts (TOAH.X) or aliquat 336 (TOMA.X) in toluene have been investigated. Three key equilibria describe the extractions: (a) M2++2HL?ML2+2H+. (b) B.X +HL?B.L+H++X? with B efficiency TOMA < TOAH and X efficiency ClO4 < NO3 < SO4. (c) ML2+B.L?B.ML3 with B efficiency toma > TOAH and Ni ~ Co > Cd > ZN.As a consequence of the conflicting orders of efficiencies of TOMA and TOAH in equilibria b and c, TOAH.X is a better synergic extractant from perchlorate medium than TOMA.X whereas the inverse is observed from nitrate and sulphate media. Equilibrium c is independent of the inorganic anions. Constants of equilibria a, b and c are given. B.ML3 species are not extracted in 1-octanol.  相似文献   

3.
The details and principles of an apparatus built for measurements of fluorescence quantum yields and cascade-free lifetimes of open-shell cations are reported. These rely on the detection of coincidences between energy selected photoelectrons and undispersed photons. The results of such measurements for CO+2, COS+, CS+2 and N2O+ in selected vibrational levels of their excited states are presented. Non-unity fluorescence quantum yields are found for some vibronic levels of CO+2(B), COS+ (A), N2OP+(A) and a non-exponential decay is observed for CS+2(A). The data yield the following values for the radiative lifetimes: CO+2(A) 124 ± 6 ns, CO+2(B) 140 ± 7 ns, COS+(A) 550 ± 50 ns and N2O+(A) 240 ± 12 ns.  相似文献   

4.
Radiative and radiationless lifetimes together with the quantum yield towards fluorescence of individual vibronic states of molecular ions can be determined by threshold electron—fluorescence photon coincidence measurements. This method is here applied to the X?2Π32,1,2 and Ã2Σ+ states of N2O+ which were also studied by high resolution photoionization resonance spectroscopy.  相似文献   

5.
Photolysis of XeF2 with Kr(123.6 nm), Hg(184.9 nm) and CO(160 to 180 nm) resonance radiation gives strong XeF[B(12)?X2Σ+] fluorescence. The two shorter wavelengths also give weak XeF[D(12)?X2Σ+] emission. The XeF(B) vibrational distribution varies with photon energy and with pressure of added buffer gas. The addition of Xe and molecular gases results in quenching of the XeF* emision. Stern-Volmer plots of the XeF* emission intensity were used to obtain quenching rate constants for Xe, N2, CO2, NF3 and F2. The XeF(BX) emission intensity is diminished by ≈ 50% with addition of one atm of Ar.  相似文献   

6.
The production of atomic iodine in the ground (2Pfrsol|3/2) and electronically excited (2P13) states following laser-induced photodissociation of I2 the region 425–498 nm was monitored directly by resonance spectroscopy. The branching ratio for iodine atom formation. R = [I(2P12)]/[I(2P32)], is above 0.5 in the region 495–498 nm in agreement with the recent observation of laser action on the atomic transition at 1315 nm following photolysis of I2 using a dye laser. The present experiments permitted deconvolution of the I2 continuous absorption spectrum below 498 into contributions from the B3 Πo,u → X 1Σg+ and 1Πtu → X1σg? transitions.  相似文献   

7.
Emission spectra resulting from reaction of “clean” N2(A3 Σu+) with copper atoms were studied using a flowing afterglow apparatus. The population distribution of the Cu states was calculated from the spectrum; it indicates that Cu atoms are excited by nearly resonant energy transfer processes. N2(A,v') + Cu(2S12) → N2(X, v) + Cu* , and that the transfer is most efficient for N2(A,v') → N2(X,v) transitions with large Franck-Condon factors. The preferential energy transfer results in population inversion between some of the Cu states.  相似文献   

8.
A comparative spectroscopic study in the visible and ultraviolet ranges was conducted on the flowing afterglows resulting from the reactions of He(2 3S) and Ne(3P0,2) metastables with CS2. Penning ionization was found to be the predominant energy transfer process. However, electron—ion recombination within the afterglows constitutes a major secondary process and gives rise to the most intense emitting system, CS(A 1 Π → X 1Σ+). Both afterglows were found to produce the CS+2(B2Σ+u-X2Πg), CS+2(A2Πu-X2Πg) and CS(a 3Π-X 1Σ+) emission systems as well as some atomic sulfur emission lines. Some intensity differences were observed and are interpreted in terms of energetics and the formation mechanisms of the emitting species. A moderately strong CS+(A 2Πi-X 2Σ+) emission system was also observed in the ehlium afterglow. In addition, a weak, sharp group of bands in the 390–420 nm range in the helium afterglow has been determined to be due to the presence of a small amount of He+ ions. This group of bands consists of two overlapping emission systems and are identified as CS(B 1Σ+ → A 1Π) and CS+(B 2Σ+ → A 2Πi).  相似文献   

9.
Pentacoordinated aminosulphur (IV) trifluorides, R2NSF3, (in this paper the lone pair in S(IV)-derivatives is always considered as a ligand) and aminosulphur(VI)-oxidetrifluorides, R2NS(O)F3, readily lose a fluoride ion to Lewis acids (AsF5, SbF5, BF3) to give sulphur-containing cationic species [R2NSF2]+ and [R2NS(O)F2]+ with tetracoordinated sulphur. Tetracoordinated neutral dialkylaminosulphur(IV)-oxidefluorides, R2NS(O)F, and amino-imino sulphur(IV)fluorides, R2NS(=NRf)F, give three-coordinated sulphur cations [R2NSO]+] or [R2NSNRf]+.The three-coordinated sulphur(VI)cation [R2NS(O)NR]+ has also been formed.  相似文献   

10.
Microwave—optical double resonance signals have been detected in a mass-selected ion-beam spectrometer for 12C16O+. With the optical excitation of fluorescence from the R1 (12) line of the (0,0) band of the A2Π32 ← X2∑ transition of 20350.6 cm?1, the microwave resonances occurred at 118101.8 ± 0.2 MHz and at 117694 ± 2 MHz corresponding to the N= 1, J = 32N = 0, J = 12 and the N = 1, J = 12N = 0, J = 12 transitions.  相似文献   

11.
12.
The metal chelates of 1-acetylpyridinium chloride-4-phenyl-3-thiosemicarbazide [(APTS)]+Cl? of the type [M(APTS)X2]+ Cl? (M = Co(II), Ni(II), Cu(II), Zn(II) or Cd(II); X = Cl, Br or 12SO4) have been prepared and characterized on the basis of elemental analysis, molar conductance, IR, electronic spectra and magnetic studies. IR spectral studies showed that the ligand coordinates via thioketo and NLH groups. Magnetic and spectral studies suggest a tetrahedral structure for Ni(II), pseudo-tetrahedral for Co(II) and square planar and/or distorted tetrahedral for Cu(II) chelates.  相似文献   

13.
The thermal dissociation of the [Co(NH3)6]X3 (X = Cl?, Br?, I?, and NO?3), [Co(en)3]X3 (X = Cl?, Br?, I?, NO?3, HSO?4 and 12 C2O2?4), cis- [Co(en)2Cl2]Cl, and trans-[Co(en)2ClBr]NO3 complexes was investigated by an electrical conductivity (EC) technique. During the thermal dissociation reactions, liquid or semi-liquid phases are formed which cause large increases in the EC of the compound. The effect of concentration of the complex in a matrix medium as well as the composition of the matrix material on the EC curves were also determined.  相似文献   

14.
Trimethyl- and triphenyl-tin(IV) hydroxide act on triphenyl(2-carboxyethyl)-phosphonium hydrochloride, which is made from 3-chloropropionic acid and triphenylphosphine, to release water in the presence of dimethylformamide (DMF) as a catalyst. The water is azeotropically distilled to drive the reaction forward and produce triphenylphosphonopropionbetainetrimethyl- and triphenyl-tin(IV) chlorides in high yield. The latter product also results from the displacement of chloride from triphenyltin(IV) chloride by the phosphobetaine, (C6H5)3P(CH2)2CO2, which is made by treating the phosphonium hydrochloride with bicarbonate, and the compounds [(C6H5)3P(CH2)2CO2Sn(C6H5)3]+X? where X = Cl, Br, I, N3, NCS, NO3, B(C6H5)4 and Co(CO)4 are made in the same way. The acetate salt results from metathesis from the chloride and lead(II) acetate. A double salt, [(C6H5)3P(CH2)2CO2SnR3]+ [R3SnX2]?, is formed for X = Cl, Br and N3 by adding additional (C6H5)3SnX to the already-formed simple salts. Double salts are also obtained from the 11 reactions between the phosphobetaine and triphenyltin(IV) isocyanate and methyldiphenyltin(IV) chloride. The phosphonium chloride double salt could be converted to the thiophosphonium derivative by heating with elemental sulfur in ethanol. The products of these novel nucleophilic displacement reactions are high melting solids. Tin-119m Mössbauer data are consistent with five-coordinated, triorganotin(IV) formulations with the exception of the diphenyl(8-hydroxyquinolinato)tin(IV) chloride salt in which the tin atom is six-coordinated, and the diphenyltin system cis-oriented. The parameters otherwise do not change with the nature of the X group, which is the tetracarbonylcobaltate derivative is tetrahedral by infrared, establishing the ionicity of the products. The chloride exhibits a molar conductivity indicative of a 11 electrolyte in DMF. A bridging acetate structure in the solid is consistent with the lowered ν(CO2) frequencies. The Mössbauer spectra of the double salts give simple doublets of lowered isomer shift (IS) and raised quadrupole splitting (QS) which may arise from a cross-linking ion pairing of the polymer chains in the solid, and the NMR spectra of the two methyltin derivatives shows only a single resonance line and tin satellites which is rationalized by a dynamic exchange process. The products are formulated as associated in carboxylate polymers with dangling triphenylphosphonium cations.  相似文献   

15.
The extraction of Co(II) with mixtures of 1-phenyl-3-methyl-4-benzoyl-pyrazol-5-one ((H)PMBP) and tri-n-octylamine (TOA) is investigated in order to explore the influence of diluents and inorganic anions with synergistic acidic extractant + liquid anion exchanger systems. Although it is proved that the same species [HTOA]+ [Co(PMBP)3]? is extracted from various inorganic media, with toluene as the diluent, the presence of ClO4? SO42? or Cl? anion modifies the distribution of the anions which are associated to (HTOA)+ in the organic phase, leading to different synergistic equilibria; with Cl? or SO42?: CO(PMBP)2 + (HTOA+,PMBP?) ?(HTOA+,Co(PMBP)3? (log K = 6.10) and with ClO4? : Co(PMBP)2 + HPMBP + (HTOA+,ClO4? ? (HTOA+,Co(PMBP)3? + H+ + ClO4? (log K = 2.34) The same synergistic equilibrium is observed for the extraction of Ni(II) from ClO4? medium, with a comparable value of the constant (log K = 2.45). The synergistic effect is cancelled in n-octanol.  相似文献   

16.
Ab initio calculations suggest that the potential energy surface for the 12A″ state of N2O+ has a secondary minimum corresponding to a strongly bent structure. This structure is computed to lie below the A2Σ + state energetically and therefore may be responsible for the isotopic scrambling observed in this energy region.  相似文献   

17.
The reactions of the lowest metastable states of Ar, Kr and Xe with XeF2 were studied in a flowing afterglow apparatus; XeF emission (from D2Π12 and B 2Π+ states) was observed in all cases. The total rate constants (cm3 molecule?1 s?1) for XeF* formation were determined as 75 × 10?11 ? Xe(3P2);64 × 10?11 ? Kr(3P2) and 20 × 10?11 ? Ar(3P0,2). The reactions of Ar(3P0,2) and Kr(3P2) with XeF2 also gave ArF* and KrF*, respectively. Analysis of these emissions indicates that at least two different mechanisms are operative: reactive quenching by the ionic—covalent curve-crossing mechanism and excitation transfer. The Ar(3P0,2 + XeF2 reaction is a sufficiently strong source of XeF(D—X) emission that the main features of the XeF(D2Π12 ? X2Σ+) system could be photographed and tentative assignments of these vibrational bands are given. The XeF(D → B) emission could not be observed and the ratio of the D—X versus the D—B transition probability must be > 1000 : 1.  相似文献   

18.
The synthesis and mechanism of formation of phosphonium salts of the type [R3P+CFXY]Z? (where X = F, Cl, Br; Y = Br, Cl; Z = Br, Cl), bis-phosphonium salts of the type [R3P+CF2P+R3]2Br?, and phosphoranium salts of the type [R3P+C?FP+R3]X? (X = Br, Cl) will be presented. The applicability of these substrates in the generation of useful nucleophilic or electrophilic synthetic intermediates will be discussed.  相似文献   

19.
The crystal structure of a bis(triphenylphosphine)iminium salt of the 1:1 adduct of [FeH(CO)4]? and dimethyl acetylenecarboxylate has been determined from three-dimensional X-ray data collected by the counter method. Single crystals belong to the triclinic space space group P1, with two units of [C36H30NP2]+[C10H7FeO8]? in a cell of dimensions: a = 13.918(2), b = 15.669(5), c = 9.909(2) Å, α = 91.22(3), β = 94.83(2), and γ = 77.62(2)°. The structure was refined to a conventional R of 0.068 for 5373 observed
reflections. The resulting structure indicates that the complex anion is η3-[trans-2,3-bis(methoxycarbonyl)acryloyl]tricarbonylferrate, the coordination around the iron atom being described as a considerably distorted trigonal bipyramid. A comparison of the present structure with the structures of related complexes suggests that the η3-acryloyl portion is best represented as an intermediate of (η3-allyl) with the oxygen atom and (η2-olefin + η1-acyl). The short Fe-C(acyl) length of 1.897(5) Å implies an enhanced back-donation of electrons from the iron atom to the acyl group.  相似文献   

20.
The electric moments and static polarizabilities of BH(1σ222, X1Σ+) and CH+ (1σ222, X1Σ+) were calculated at the experimental internuclear separation in the LCAO SCF MO approximation. Most of the molecular properties reported in this paper for BH and CH+ appear for the first time and should be close to the Hartree—Fock limit. All tensors up to the fourth rank have been included in this study. The isotropy and anisotropy of the α, β and γ tensors are, in atomic units. α = 22.71, Δα = ?0.26, β = 55.1, Δβ = ?183.7, γ = 12428, Δ1γ = 37895, Δ2γ = 25120 for BH and α = 7.73, Δα = 0.39, β = ?12.4, Δβ = ?11.7, γ = 344, Δ1γ = 1515, Δ2γ = 750 for CH+.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号