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101.
本文采用激光诱导荧光的方法测定了九种L4EuQH型β-二酮铕配合物的荧光寿命(其中Q表示胺的衍生物)。结果表明,对相同Q的配合物的6130Å,5910Å和5797Å三个荧光峰所测得的寿命均相同。不同的Q可能通过氢键作用对配合物的荧光寿命有一定影响。 相似文献
102.
103.
Wang J Fang YQ Bourget-Merle L Polson MI Hanan GS Juris A Loiseau F Campagna S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(33):8539-8548
A new family of ruthenium(II) complexes with multichromophoric properties was prepared based on a "chemistry-on-the-complex" synthetic approach. The new compounds are based on tridentate chelating sites (tpy-type ligands, tpy=2,2':6',2'-terpyridine) and most of them carry appended anthryl chromophores. Complexes 2 a and 2 b were synthesized through the Pd-catalyzed Suzuki coupling reaction between 9-anthrylboronic acid and the chloro ligands on the presursor species 1 a and 1 b, respectively. The monocoupling product 2 c was also synthesized as the starting complex for a dimetallic complex under optimized Suzuki coupling conditions. The palladium(0)-catalyzed homocoupling reaction on complexes 1 a and 2 c led to dimetallic Ru(II) species 2 d and 2 e, respectively. The solid structures of complexes 2 a and 2 b were characterized by X-ray diffraction. The absorption spectra, redox behavior, luminescence properties (both at room temperature and at 77 K), and transient absorption spectra and decays of 2 a-e were investigated. The absorption spectra of all new species are dominated by ligand-centered (LC) bands in the UV region and metal-to-ligand charge-transfer (MLCT) bands in the visible region. The new compounds undergo reversible metal-centered oxidation processes and several ligand-centered reduction processes, which have been assigned to specific sites. The complexes exhibit luminescence both at room temperature in fluid solution and at 77 K in rigid matrices; the emission was attributed to (3)MLCT states at room temperature and to the lowest-lying anthracene triplet ((3)An) at low temperature, except for 2 c, which does not contain any anthryl chromophore and whose low temperature emission is also of MLCT origin. The luminescence lifetimes of complexes 2 a-d showed that multichromophoric behavior occurs in these species, allowing the luminescence lifetime of the Ru(II)-based chromophores to be prolonged to the microsecond timescale, with the anthryl groups behaving as energy-storage elements for the repopulation of the (3)MLCT state. Nanosecond transient-absorption spectroscopy confirmed the equilibration process between the triplet MLCT and An levels at room temperature. Thermodynamic and kinetic factors governing the equilibration time and the lifetime of the equilibrated excited state are discussed. 相似文献
104.
Veerabhadrarao Kaliginedi Mohamad Akbar Ali B. Rajakumar 《International journal of quantum chemistry》2012,112(4):1066-1077
Rate coefficients for the reaction of the hydroxyl radical with CH3OCH2F (HFE‐161) were computed using transition state theory coupled with ab initio methods, viz., MP2, G3MP2, and G3B3 theories in the temperature range of 200–400 K. Structures of the reactants and transition states (TSs) were optimized at MP2(FULL) and B3LYP level of theories with 6‐31G* and 6‐311++G** basis sets. The potential energy surface was scanned at both the level of theories. Five different TSs were identified for each rotamer. Calculations of Intrinsic reaction coordinates were performed to confirm the existence of all the TSs. The kinetic parameters due to all different TSs are reported in this article. The rate coefficients for the title reaction were computed to be k = (9 ± 1.08) × 10?13 exp [?(1,713 ± 33)/T] cm3 molecule?1 s?1 at MP2, k = (7.36 ± 0.42) × 10?13 exp [?(198 ± 16)/T] cm3 molecule?1 s?1 at G3MP2 and k = (5.36 ± 1.57) × 10?13 exp [?(412 ± 81)/T] cm3 molecule?1 s?1 at G3B3 theories. The atmospheric lifetimes of CH3OCH2F at MP2, G3MP2, and G3B3 level of theories were estimated to be 20, 0.1, and 0.3 years, respectively. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012 相似文献
105.
G. Çelik E. Akın H. Ş. Kılıç 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(3):325-330
The atomic transition probabilities are calculated for
individual lines between some quartet terms of 3p↦4d and 3p↦5d
transition arrays using weakest bound electron potential model theory
(WBEPMT). In the determination of relevant parameters which are needed for
calculation of transition probabilities, we employed numerical
non-relativistic Hartree-Fock wave functions for expectation values of
radius in both ground and excited states unlike to NCA method used on
traditional WBEPMT procedure. We have obtained very good agreement between
our results and the accepted values taken from NIST. 相似文献
106.
Z. H. Yang S. B. Du X. T. Zeng H. W. Chang B. L. Zhang K. X. Zhu D. Y. Yu X. H. Cai 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(1):33-36
Spectra for Δn = 0 transitions of the type
2s22pk-2s2pk+1 or 2s2pk-2pk+1 from highly ionized
sulfur produced in beam-foil excitation are investigated and compared to
similar spectra measured with other types of light sources. In the
experiment, fifty lines have been identified, of which eleven lines are new
and accurately measured. Analysis of spectra was based on comparisons with
other experimental results and calculated values. 相似文献
107.
We have done relativistic calculations for the evaluation of energy levels, oscillator strengths, transition probabilities
and lifetimes for Cr VIII ion. Use has been made of configuration interaction technique by including Briet-Pauli approximation.
The energies of various levels from the ground state to excited levels of 3s3p6, 3s23p43d, 3s23p44s, 3s23p44d of Cr VIII are given in LSJ coupling scheme after fine-tuning and are compared with the experimental results compiled in
the NIST Data Base. Many new lines have been predicted which have not appeared so far in the NIST Data. 相似文献
108.
Summary. Since the first application of laser diodes (LD) for the determination of fluorescence lifetimes in our group in 1995, great
technical improvements have been made to increase the time resolution of the apparatus. Using the phase fluorometric method,
measurements down to 100 ps are now possible. Values can be measured in steps of 10 ps with good reproducibility using a high-frequency
signal generator and a GHz digital storage oscilloscope. No additional optical equipment is necessary for this new method.
Following an easy calibration procedure, results are available within one minute without any adjustments. The components of
the new apparatus including light source, sample chamber for standard fluorescence cuvettes, and detection unit are situated
in a 12 × 13 × 9 cm setup. The apparatus was tested with different fluorophores, and the results correlate very well with
known values in the range of 0.1 to 1000 ns.
Received February 16, 2000. Accepted March 13, 2000 相似文献
109.
Subhodip Samanta Pinki Saha Sardar Shyam Sundar Maity Anirban Pal Maitrayee Basu Roy Sanjib Ghosh 《Journal of Chemical Sciences》2007,119(2):175-183
A comparative time-resolved emission studies of several naphtho-crown ethers I–V, where metal ions can be complexed in a predetermined orientation with respect to the naphthalene (Naph) π-plane and naphthalene-linked aza crown ethers (L1 and L2) have been presented. In both the systems, crown ethers and aza
crown ethers, naphthalene fluorescence gets quenched. In the systems I to V, the quenching is mainly due to efficient spin-orbit coupling (SOC) leading to greater population of the lowest triplet state
of naphthalene. This SOC depends on the orientation of the crown ring with respect to the Naph-π-plane. However, in the systems L1 and L2, the quenching is due to photoinduced electron transfer (PET) from nitrogen lone
pair of the aza crown ring to naphthalene moiety and consequent exciplex formation. The results have been interpreted using
the time-resolved emission studies of all the compounds in various solvents, their alkali metal ion complexes, and protonated
ligands. 相似文献
110.
É. Biémont H.-P. Garnir P.-H. Lefèbvre P. Palmeri L. Philippart P. Quinet D. Rostohar C. J. Zeippen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(1):91-99
Oscillator strengths have been calculated for the transitions depopulating levels of the 3s23p3, 3s3p4 configurations of K V, of the 3s23p2, 3s3p3 configurations of K VI and of the 3s23p, 3s3p2, 3p3 and 3s3p3d configurations of K VII. A multiconfiguration Dirac-Fock method, incorporating the relativistic two-body Breit
interaction and quantum electrodynamics corrections due to self-energy and vacuum polarization, has been used for the calculations.
The reliability of this approach has been tested by comparison with relativistic Hartree-Fock calculations and also with some
experimental measurements performed by beam-foil spectroscopy at a beam energy of 1.7 MeV. 相似文献