共查询到16条相似文献,搜索用时 0 毫秒
1.
T.W. Tunnell C. Can C.P. Bhalla 《Journal of Quantitative Spectroscopy & Radiative Transfer》1982,27(4):405-416
Theoretical X-ray transition energies, lifetimes and partial multiplet fluorescence yields are presented for all spectroscopic terms of electron configurations with a single K-shell vacancy and varying number of electrons in the L-shell and M1-subshell for multiply-ionized silicon. 相似文献
2.
C. Reylé P. Bréchignac 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(2):205-210
Fluorescence spectra of naphthalene, C10H8, were obtained in the laboratory under conditions which provide an appropriate simulation of the cometary conditions: super-cooled
gas phase molecules in a collision-free environment. Five spectra were recorded, the excitation energies ranging from 1422
to 5293 cm−1 above the first electronic state S1 at 32 020 cm−1. A comparison with previous jet-cooled naphthalene fluorescence spectra obtained by Beck et al. [1] and Hermine [2] shows that the former results are not consistent with the present ones. Spectra obtained by Beck et al. show weaker intensities at greater wavelengths compared to those obtained by Hermine and ourselves. We also measured the
fluorescence lifetimes by recording the fluorescence decay as a function of time after the excitation of the molecules by
monochromatic lasers and deduced the fluorescence quantum yields. A synthetic emission spectrum under solar irradiation is
obtained for astrophysical implications. 相似文献
3.
D. Demir Y. Şahin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(2):211-216
The effect of external magnetic field on the Kα
and Kβ X-ray production cross-sections and K shell fluorescence
yields for ferromagnetic elements Nd, Gd and Dy and paramagnetic elements Eu
and Ho have been measured at the excitation energy of 59.5 keV γ
-rays from 241Am radioactive source of strength 100 mCi in the
external magnetic field of intensities ±0.75 T. Furthermore,
IKβ /IKα intensity ratios for these elements have been
measured in the external magnetic field. The K X-rays from different targets
were detected using a high resolution Si(Li) semiconductor detector. For B = 0, the measured K X-ray production cross-sections,
K shell fluorescence
yields and the IKβ /IKα intensity ratios were compared
with the experimental and theoretical data in literature. The results have
shown that the fluorescence parameters as photoionization cross section,
fluorescence yield, radiation rates and spectral linewidth can change when
the irradiation is conducted in a magnetic field. 相似文献
4.
C.P. Bhalla T.W. Tunnell 《Journal of Quantitative Spectroscopy & Radiative Transfer》1984,32(2):141-158
We have calculated theoretical transition rates and transition energies for the states of the excited electron configurations, 1s 2s nl and 1s 2p nl, of lithium-like argon. The values of n considered range from n=2 to n=4 with all allowed values of l included, l=0 to l=n-1. We present numerical results for the theoretical lifetimes, transition energies, fluorescence yields, and nonradiative branching ratios. These quantities are related to the dielectronic recombination rates and cross sections of helium-like argon. 相似文献
5.
实验测定了激发波长在 591~ 594nm范围 ,压力在 0 .1~ 15Pa时 ,NO2 分子激光诱导荧光衰减曲线 ,作几何修正后应用Stern Volmer模型 ,得到了零压辐射寿命τ0 ( =1/k0 )和碰撞猝灭速率常数kq,结果与文献报道基本一致。对NO2 分子激发态能级的反常长寿命和一定压力下出现的双指数衰减等进行了较详细的讨论。 相似文献
6.
Li (i = 1, 2 and 3) X-ray fluorescence cross sections for Ta, W, Au, Hg, Tl, Pb, Bi, Th and U have been measured using the 59.54 keV incident photons energy in the external magnetic field of intensity +0.60 T. The values of Li subshell fluorescence yields (w1, w2 and w3) have been measured for the same elements using the previously measured cross section values and the theoretical Li subshell photoionisation cross sections, Coster–Kronig transition probabilities and emission rates. It is observed that the measured Li subshell X-ray fluorescence cross section and Li subshell fluorescence yield values for B = 0 are in good agreement with the theoretical ones evaluated using Li subshell fluorescence yield and Li subshell photoionization cross section. Furthermore, the results show that the atomic parameters such as spectral linewidth, radiation rates, photoionization cross section and fluorescence yield can change when the irradiation is conducted in a magnetic field. 相似文献
7.
S.S. Chebotaryov A.A. Volegov L.A. Pesin S.E. Evsyukov N.A. Moskvina I.V. Gribov V.L. Kuznetsov 《Physica E: Low-dimensional Systems and Nanostructures》2007,36(2):184-189
Modifications of the photoelectron and C KVV Auger spectra during the long-term surface degradation of partially crystalline PVDF under simultaneous soft X-ray and electron followed by ion irradiation are reported. Deep radiative carbonization brings about the formation of carbynoid structures (chain-like carbon) in the surface, while the number of interchain cross-links is insignificant. As a result, the shape of the electron emission spectra of carbon in the carbonized sample essentially differs from that of graphite and PVDF. The ion bombardment of the carbonized sample destroys one-dimensional structure due to the formation of cross-links. Thus, carbon atoms transit into sp2-hybrid state and, therefore, the photoelectron and Auger spectra show features characteristic for microcrystalline graphite. 相似文献
8.
Erhan Cengiz Zekeriya Biyiklioglu Nuray Kup Aylikci Volkan Aylikci Gokhan Apaydin Engin Tirasglu Halit Kantekin 《化学物理学报》2010,23(2):138-144
对钴、镍、铜、锌元素组成的不同配合物K壳层X射线的产生截面、谱线强度比、俄歇辐射强度比进行了测定,同时研究了化学效应对K壳荧光参数和俄歇辐射强度比的影响,并根据电荷转移过程解释了这些参数的变化. 采用59.5 keV的γ射线241Am的环形放射源对样品进行激发. 用分辨率为150eV的Ultra-LEGe探测器在5.9 keV测定样品产生的K壳X射线. 相似文献
9.
Ö. Sö?üt 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,97(3):388-394
The Coster-Kronig (CK) enhancement effect was measured for L3 subshell X-rays using the experimental Lα X-ray production cross-section, the fraction of Lα X-rays, L3 subshell fluorescence yields and L3 subshell photoionisation cross-section. The samples were excited by gamma-rays with 59.5 keV energy from a 75 mCi radioisotope source and L X-rays emitted from samples were counted by a Si(Li) detector with resolution 155 eV at 5.96 keV. Variation of enhancement effect of CK transition of L3 X-rays of La and Ce compounds was measured to be more than that of Ba. Ba has a partially filled 6s orbital whereas La and Ce have partially filled 5d and 4f orbitals, respectively. 相似文献
10.
Ali Kaya Mehmet Ertugrul 《Journal of Electron Spectroscopy and Related Phenomena》2003,130(1-3):111-118
Li (i=1, 2 and 3) X-ray production cross sections have been measured for 14 elements in the atomic number range 55≤Z≤81 at 15.73 keV. The values of Li subshell fluorescence yields (ω1, ω2 and ω3) have been determined using the presently measured X-ray production cross sections and the theoretical Li subshell photoionization cross sections values, Coster–Kronig transition probabilities and radiative emission rates. The measured X-ray production (XRP) cross-sections and fluorescence yield values were compared with the theoretical and semi empirical values, respectively. 相似文献
11.
Joel M. Kauffman Peter T. Litak John A. Novinski Charles J. Kelley Alem Ghiorghis Yuanxi Qin 《Journal of fluorescence》1995,5(3):295-305
Absorption and fluorescence emission spectral data, as well as fluorescence quantum yields (f), were determined for 41p-oligophenylene compounds containing 2–6, 8, and 10 benzene rings. Of 29 compounds containing carbon-bridged rings (fluorenes), 28 were dialkylated on each bridge for improved solubility and photostability. Absorption maxima for oligophenylenes were observed at wavelengths as long as 366 nm, emission maxima to 437 nm, and molar extinction coefficients () as large as 153,000 L/mol-cm; all three exceeded predicted maximum values for the corresponding unbridged oligophenylenes. The substitution of furan for benzene or carbazole for a fluorene (two examples each) bathochromically shifted absorption and emission maxima. Dialkylated carbon bridges bathochromically shifted absorption and emission maxima, and lowered f in biphenyl and in one terphenyl analogue, but appeared to cause no diminution of f in higher oligophenylenes. Bis(2-methoxyethyl) substitution on the bridges, incorporated to provide solubility in polar solvents, lowered f in all examples. Tertiary alkyl substituents on terminal rings bathochromically shifted the absorption and emission maxima and generally increased f. The loose bolt effect, which lowers f in mononuclear substituted benzenes, may operate in 9,9-dialkylfluorenes, but not in 2,7-di-t-butylfluorene or in higher oligophenylenes. Cyclic ether and methoxy substituents as auxofluors on terminal rings generally bathochromically shifted absorption and emission maxima and increased and f. Cyano substituents bathochromically shifted absorption and emission maxima, and increased , but lowered f slightly. 相似文献
12.
Nkosiphile Masilela 《Journal of luminescence》2010,130(10):1787-1793
This work reports on the synthesis, characterisation and photophysical properties of new unquaternized β-2,(3)-tetra-(2 pyridiloxy) aluminium(III) (3a), silicon(IV) (3b), titanium(IV) (3c) phthalocyanines and their water-soluble quaternized counterparts, 4a, 4b and 4c, respectively. The water-soluble silicon(IV) (4b) and titanium(IV) (4c) phthalocyanine derivatives were found to be aggregated in aqueous media but were partially or fully disaggregated in the presence of a surfactant Cremophor® EL (CEL). The photophysical properties of aggregated complexes were investigated both in the presence of CEL and in pH 11 alone. Low triplet and fluorescence yield were obtained in pH 11 but an improvement was achieved upon addition of CEL for the aggregated complexes. The unquaternized silicon(IV) phthalocyanine complex (3b) gave the highest triplet quantum yield of 0.77 in DMF followed by its quaternized derivative (4b) with triplet yield of 0.73 in pH 11 plus CEL. The highest triplet lifetime of 220 μs was obtained for 4b in the presence of CEL. Higher fluorescence yields of 0.23 were obtained for quaternized water-soluble aluminium(III) phthalocyanine derivative (4a) in the presence of CEL. 相似文献
13.
By means of the relation of ionicity and the ionization energies of hydrogenlike atoms, the soft X-ray spectra are calculated for the hydrogenlike sodium, magnesium and aluminium atoms. The calculated results are in good agreement with the experiments. 相似文献
14.
15.
Theoretical study on K, L, and M X-ray transition energies and rates of neptunium and its ions 下载免费PDF全文
The transition energies and electric dipole (El) transition rates of the K, L, and M lines in neutral Np have been theoretically determined from the MultiConfiguration Dirac-Fock (MCDF) method. In the calculations, the contributions from Breit interaction and quantum electrodynamics (QED) effects (vacuum polarization and self-energy), as well as nu- clear finite mass and volume effects, are taken into account. The calculated transition energies and rates are found to be in good agreement with other experimental and theoretical results. The accuracy of the results is estimated and discussed. Furthermore, we calculated the transition energies of the same lines radiating from the decaying transitions of the K-, L-, and M-shell hole states of Np ions with the charge states Np1+ to Np6+ for the first time. We found that for a specific line, the corresponding transition energies relating to all the Np ions are almost the same; it means the outermost electrons have a very small influence on the inner-shell transition processes. 相似文献
16.
D. Demir Y. Şahin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(1):17-22
The effect of an external magnetic field on the L3
subshell fluorescence yields (ω3 ) and level widths ($\Gamma_{L_3}$) for paramagnetic Ta, W, Tl, Th and U have been investigated using the
59.54 keV incident photon energy in the external magnetic field of
intensities ±0.60 T. L3 X-ray fluorescence cross sections ($\sigma_{L_3}^{X}$)
have been measured for the same elements. The measured ω
3, $\Gamma_{L_3} $
and $ \sigma_{L_3}^X$ values for B = 0 are in good
agreement with the theoretical values. It was observed that the values of
$\sigma_{L_3}^X$
and ω3 with the applied magnitude of the
magnetic field in both directions show a decreasing trend for paramagnetic
Ta, W, Tl, Th and U. Furthermore, in the presence of an external magnetic
field, the values of
$\Gamma_{L_3}$
show an increasing trend for
the same elements. The results show that the atomic parameters such as
spectral linewidth, radiation rates, photoionization cross section and
fluorescence yield can change when the irradiation is conducted in a
magnetic field. 相似文献