The fluorescence spectrum of iodine was investigated from 200 to 520 nm in the presence and absence of buffer gases following excitation of I2 with 193 nm photons. The pressure dependence of the fluorescence and tentative transition assignments for one new and several less well-known I2 emission bands are discussed. 相似文献
The emission spectra of I2 excited at 607 nm in CCl4 and cyclohexane exhibit resonance Raman emission bands accompanied by featureless red-infrared continua. and are identical for 1.5 μs and 3 ps pumping pulses. The continua consist primarily of vibrationally unrelaxed B3 Πo+u → XI ∑g+ fluorescences. 相似文献
Raman spectra of VCl4 and SnI4 in solution are obtained using the exciting lines of a HeNe and an Ar+ laser. The spectra show a pre-resonance Raman effect with an enhancement of the stretching vibrations for shorter wavelengths of excitation. The features of the intensity variation are discussed quantitatively in terms of the frequency factors given by Albrecht and Hutley. 相似文献
Raman spectra of TiBr4 and Til4 in solutions were obtained using the excitation lines of a HeNe and Ar+ laser. The spectra of TiBr4 showed a pre-resonance effect with selective enhancement of the stretching vibrations for the shorter wavelength of excitation. A typical resonance Raman effect was observed for TiI4 by the 5145 and 4880 Å excitation lines, which lie close to the maximum of the first absorption band, giving an intense overtone progression of the totally symmetric mode ν1. 相似文献
The A 2Πu-X 2Πg electronic emission spectrum of I2+ has been recorded at a low rotational temperature in a crossed molecular beam/electron beam apparatus. Six vibrational sequences with five or more members have been assigned to progressions in ν′, giving ω′e = 122±8 cm−1, but a full vibrational analysis has not been possible. It is not known whether this is due to the relatively poor resolution (≈5 cm−1) at which the spectrum has been recorded or because the A 2Πu state is perturbed in one or both spin-orbit components. Existing data on the A state of I2+ are reviewed. 相似文献
The effects of nuclear spin-spin coupling are included in the analysis of the nuclear hyperfine structure of the R(127) line of the 11-5 band in the B-X electronic band system of I2. The fit to the experimental data is improved over earlier fits in which only the effects of nuclear spin-rotation interaction and nuclear electric quadrupole coupling were considered. The electron-coupled contribution to the spin-spin constant of the upper state is determined to be dE = ?36.3 ± 8.5 kHz. However, the fit (standard deviation = 59.8 kHz) is still not at the level of the experimental precision (40 kHz) and further measurements are in progress to test the model used for the hfs hamiltonian. 相似文献
The S2− molecule ion in NaI crystals exhibits multiple-order resonance Raman scattering at 80 K with little background luminescence. Relative scattering efficiencies measured for up to nine Raman overtones are compared with the theory of Hizhnyakov and Tehver. 相似文献
Infrared spectra of the CH3NH3+, CH3ND3+, CD3NH3+ and CD3ND3+ ions in bis(methylammonium)hexachloroplatinate(IV) have been recorded. The spectra are entirely consistent with the C3v symmetry reported for the methylammonium ion, at temperatures between room temperature and 90 K. No spectral manifestations of the phase transition, which in (CH3NH3)2PtCl6 has been reported to take place at 125 K, were observed. Assignments of the infrared-active fundamentals have been made for each ion and a normal-coordinate analysis has been performed using the observed fundamental frequencies. Comparison with the infrared spectra of other methylammonium salts shows that hydrogen bonding in (CH3NH3)2PtCl6, if present, is weak. 相似文献
New rotational analyses have been made of the B3Π0+u—X1Σ+g systems of 79Br2, 81Br2 and 127I2. The density of vibrational states near the dissociation limit in the upper states follows the LeRoy—Bernstein predictions for n = 5. From short extrapolations, the ground state dissociation energies are found to be: D0(79Br81Br) = 15895.6 cm?1, D0(127I2) = 12440.1 cm?1. 相似文献
The state population of CF3Br is found to be entirely non-thermal under certain molecular beam conditions; the various vibrational modes show distributions which can be described using mode-temperatures differing by as much as a factor of 1.7. Considerable vibrational excitation (ν1, ν2 + ν3) was produced with a focused cw CO2 laser. A structured excitation spectrum was observed. 相似文献
The thermal dissociation of the [Co(en)3](SCN)3 and [Co(en)3]I3 complexes was studied by thermogravimetry, differential thermal analysis, thermomagnetic analysis, pyrolytic techniques, evolved gas analysis, and mass spectrometry, in vacuo and nitrogen atmospheres. It was found that the [Co(en)3](SCN)3 complex dissociated in four steps: It was not possible to elucidate the intermediate compounds formed in the thermal dissociation of the [Co(en)3]I3 complex. 相似文献
Visible and ultraviolet fluorescence of I2, following excitation by ArF/193nm excimer laser pulses, was recorded for different pressures of argon buffer gas in a flow
system. Dispersed fluorescence spectra due to the transitionsD’(2g) → A’(2y andD(0n+
)→X0
g+
) were analysed by inversion and spectral simulations. Thus vibrational distributions in the emitting states were obtained
as a function of pressure to determine the mechanism of relaxation to populate the lowest quantum levels of theD’ state, which are the emitting states in the iodine laser. Fast intersystem crossing is found to occur from initially populated
vibrational levels of theD state to other ion-pair states correlating with the ground state ions, followed by rapid relaxation, involving both direct
vibrational relaxation within individual states and intersystem crossing between states. 相似文献
Compounds [Ge38.3Sb7.7]I7.44, [Ge38.1P7.9]I8, and [Ge30.5Sn7.7P7.75]I7.88 with the clathrate type-I structure were synthesized. They crystallize in the cubic space group Pm[`3]nPm\bar 3n with the unit cell parameter a = 10.8592(9), 10.4983(12), and 10.7210(10) ? (Z = 1), respectively. Their crystal structure represents the germanium(tin)-pnictogen framework, capturing the guest iodine
anions in its cavities. All compounds have no vacancies in the host substructure; however, two of them show vacancies in the
guest positions. The atomic distribution over the framework sites is of the most interest as it follows trends associated
with the relative electronegativities of the atoms composing the framework. The results of the band structure calculations
and application of the Zintl counting scheme are also discussed in relation to potential thermoelectric properties. 相似文献
Single crystals with I0.33NbSe4 composition are grown, along with NbSe2 crystals, by iodine vapor transport from NbSe3. Single phase powder is obtained by heating the elements in corresponding proportions at 700°C. The structure has been studied by X-ray diffraction on a single crystal. The symmetry is tetragonal with the following parameters of the unit cell a = 9.489 Å, c = 19.13 Å. The space group is with Z = 12. The structure is built up with chains of rectangular [NbSe8]-antiprisms. Iodine atoms are located between these chains. 相似文献
The mid-infrared spectrum of the ionic complex He---NH4+ has been recorded in the vicinity of the triply degenerate ν3 (t2) vibration of the free ammonium ion. Apart from a small blue shift (≈ 0.7 cm−1), the spectrum of the complex closely resembles that of the monomer. Ab initio calculations predict a vertex-bound minimum structure with an intermolecular well depth De ≈ 150 cm−1, a center-of-mass separation of Re ≈ 3.17 Å and barriers for internal rotation less than 30 cm−1. 相似文献
A straightforward and general method has been developed for the synthesis of phthalimide derivatives from 2-iodobenzamides and PPh3/I2/HCOOH in the presence of a catalytic amount of Pd(OAc)2. The reaction results demonstrate that PPh3/I2/HCOOH is a facile, efficient and safe CO source. The whole process is carried out in toluene at 80?°C and furnishes the desired products in good to excellent yields. 相似文献
The rate coefficient, k1, for the reaction I2+F2k1→ products has been measured at room temperature to be k1 = (1.9 = 0.4) × 10?15 cm3/molecule s. The macroscopic rate is compared to microscopic cross-section data obtained from molecular beam experiments and is found to be consistent with the bimolecular reaction I2 + F2→ I2F + F.DG|National Research Council/Resident Research Associate. 相似文献