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81.
聚氯乙烯制成的一次性医疗器械在生产加工过程中,常使用环己酮作为部件粘结剂。由于残留的环己酮可释放到医疗器械管道和储存的溶液中,并可能对病人产生一定的副作用,因此,医疗器械中环己酮的快速检测日显重要。利用自主研制的紫外光电离-离子迁移谱装置对环己酮进行检测,检测限为15ppb,检测线性动态范围达到三个数量级。分别对三个品牌一次性输液器包装中的气体进行迁移谱测量,获得包装内环己酮的平均浓度分别为16.78,17.59和46.69ppm。该方法可以用于一次性医疗器械中环己酮等有机溶剂的快速检测,进行医疗器械产品的质量监控。 相似文献
82.
A.L. Morales N. Raigoza E. Reyes-Gmez J.M. Osorio-Guilln C.A. Duque 《Superlattices and Microstructures》2009,45(6):590-597
Double quantum well heterostructures are quite important for the exploration of correlated electron states in two-dimensional systems. By using the variational procedure, within the effective-mass and parabolic-band approximations, the effects of both electric field and hydrostatic pressure on the shallow-donor-impurity related polarizability and photoionization cross-section in GaAs–Ga1−xAlxAs double asymmetric quantum wells are presented. The electric field is considered to be applied along the growth direction. It is found that the impurity binding energy and polarizability can be tuned by means of an applied external electric field or hydrostatic pressure in asymmetric double quantum wells, a behavior which could be used in the design and construction of semiconductor devices. The photoionization cross-section magnitude increases as the pressure and applied electric field are increased, except beyond the Γ–X crossover in the barrier material, where a decrease of the photoionization cross-section is expected due the smaller confinement of the impurity wave function. 相似文献
83.
Using the unified method, the inverse processes of photoionization and electron–ion recombination are studied in detail for neutral chromium, (), for the ground and excited states. The unified method based on close-coupling approximation and R-matrix method (i) subsumes both the radiative recombination (RR) and dielectronic recombination (DR) for the total rate and (ii) provides self-consistent sets of photoionization cross sections σPI and recombination rates αRC. The present results show in total photoionization of the ground and excited states an enhancement in the background at the first excited threshold, state of the core. One prominent phot-excitation-of-core (PEC) resonance due to one dipole allowed transition (6S-6Po) in the core is found in the photoionization cross sections of most of the valence electron excited states. Structures in the total and partial photoionization, for ionization into various excited core states and ground state only, respectively, are demonstrated. Results are presented for the septet and quintet states with n≤10 and l≤9 of Cr I. These states couple to the core ground state 6S and contribute to the recombination rates. State-specific recombination rates are also presented for these states and their features are illustrated. The total recombination rate shows two DR peaks, one at a relatively low temperature, at 630 K, and the other around 40,000 K. This can explain existence of neutral Cr in interstellar medium. Calculations were carried out in LS coupling using a close-coupling wave function expansion of 40 core states. The results illustrate the features in the radiative processes of Cr I and provide photoionization cross sections and recombination rates with good approximation for this astrophysically important ion. 相似文献
84.
Elementary cholesterol was analyzed with IR laser desorption/tunable synchrotron vacuum ultraviolet photoionization mass spectrometry. An exclusive molecular ion of cholesterol is observed by near threshold single-photon ionization with high efficiency. Fragments are yielded with the increase of photon energy. The structures of various fragments are determined with commercial electron ionization time-of-flight mass spectrometry. Dominant fragmentation pathways are discussed in detail with the aid of ab initio calculations. 相似文献
85.
I. D. Petrov V. L. Sukhorukov M. W. Ruf H. Hotop 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(3):289-302
Absolute photoionization cross sections for Ne atoms in the excited
levels (Paschen notation
) were calculated at near threshold energies within
the configuration interaction Pauli-Fock approach including core polarization.
The computed spectra and the lineshape parameters of the odd parity
2p1/2
5ns′/d′ autoionizing resonances are
found to be in good agreement with high resolution laser spectroscopic
results. Guided by the theoretical results, improved analyses of the measured
spectra by superimposed Fano-type profiles were achieved. Theoretical
predictions are presented for resonances which have not yet been studied
experimentally. In addition, we report the absolute partial photoionization
cross sections for the 2P3/2 and 2P1/2 channel at
photoelectron energies up to 7 eV. Except for the highest lying 2p1(1S0) level, these cross sections monotonically decrease with
energy (as reported earlier in single-electron calculations for the
Ne(2p53p) configuration) with branching ratios which essentially reflect
the core composition of the 2px levels. For the 2p1 level the resonance structure and the
partial cross sections are strongly influenced by a
Cooper-Seaton minimum in the d3/2
′ channel,located just above the 2P1/2 ionization limit. 相似文献
86.
Hideki Katayanagi Bhim P. Kafle Takanori Mori Yasuhiro Takabayashi Yoshihiro Kubozono 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(9):1590-1598
The photoion yield spectra of an endohedral metallofullerene Pr@C82 were measured in the photon energy range of 100-150 eV by using time-of-flight mass spectrometry. Parent ions Pr@C82+, Pr@C822+ and Pr@C823+ were observed in the mass spectra. The photoion yield spectra of Pr@C822+ showed a broad peak at 120-140 eV that was assigned to the 4d-4f giant dipole resonance of the encapsulated Pr atoms. Absolute photoabsorption cross sections of Pr@C82 were evaluated from the photoion yield spectra to be 37±12 Mb at 110 eV (off-resonance) and 52±13 Mb at 130 eV (on-resonance). These cross sections of Pr@C82 were compared with the results of Ce@C82, the only metallofullerene whose photoionization properties have ever been studied near the 4d edge of the encapsulated metal atom. The enhancement of photoabsorption due to the giant resonance was found to be similar in Pr@C82 and Ce@C82, but there are marked differences in the peak shapes, which can be explained as due to interference effects between the fullerene cage and the encapsulated metal atoms. 相似文献
87.
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
88.
The effect of uniform electric and magnetic fields on binding energy and photoionization cross-section of an off-axis hydrogen-like donor impurity in a QWW, approximated by a cylindrical well of finite depth, is investigated within the framework of variational approach. The dependencies of the binding energy and photoionization cross-section on electric field strength, magnetic field induction, wire radius and impurity position are obtained. The cases when the polarization vector of incident radiation is parallel and perpendicular to the wire axis are both discussed. 相似文献
89.
90.
J. Zeng J. Yuan Z. Zhao Q. Lu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(2):167-173
Extensive configuration interaction wave functions are determined to calculate the energies of the inner-shell excited states
and the oscillator strengths of the optically allowed inner-shell transitions of C IV ion. Photoionization cross-sections
of the ground and the first excited states of C IV ion are also obtained by using the R-matrix method. The positions of some
inner-shell excited states are redetermined more accurately by analyzing the resonance structures of the photoionization processes.
Some of the results are compared with other available theories and experiments.
Received 29 September 1999 and Received in final form 8 December 1999 相似文献