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71.
Š. Urban D. Papoušek M. Bester Koichi Yamada G. Winnewisser A. Guarnieri 《Journal of Molecular Spectroscopy》1984,106(1):29-37
The data on the inversion spectrum in the ν2 state of 14ND3 [F. Scappini, A. Guarnieri, and G. DiLonardo, J. Mol. Spectrosc.95, 20–29 (1982)] have been extended by measuring frequencies of 25 new transitions. A simultaneous least-squares analysis of these data with the ground state microwave transition frequencies and the diode laser measurements of the ν2 band has been carried out. Improved sets of molecular parameters have been obtained for 14ND3 and 15ND3, including the ground and ν2 state inversion splittings, ν2 band origins, rotational and centrifugal distortion constants, and the parameters of the Δk = ±3n vibrational-rotational interactions. 相似文献
72.
E. Michael F. Lewen R. Gendriesch J. Stutzki G. Winnewisser 《International Journal of Infrared and Millimeter Waves》1999,20(6):1073-1083
We report an automatic frequency control (AFC) for an optically pumped far infrared (FIR) ring laser applicable for high resolution THz sideband spectroscopy by mixing a fraction of the laser power and a harmonic of a phase-locked synthesizer on a planar Schottky diode. We achieve a relative frequency accuracy of about 0.5 kHz rms at 803 GHz (
15
NH
3
) and about 1 kHz rms at 1626.6 GHz (CH
2
F
2
) over hours of lock time. The absolute frequency accuracy is estimated to be about 5 kHz at 1626.6 GHz. 相似文献
73.
Infrared-to-visible wave-length conversion in the Yb3+−Er3+ doped phosphors system has been described by a simple three level model based on two ions mechanism. The excitation in the
range of 900–1000 nm of an IR-photon is first absorbed by Yb3+ ion as a sensitizer attributed to the resonant energy transition in Er3+ ion from 4
I
3/2 → 4
S
15/2 and 1
F
9/2 → 4
I
15/2, respectively for green and red emission. The essential energy transfer processes in this system i.e. upconversion from 4
I
11/2 and 1
I
13/2, cross-relaxation from 4
S
3/2 and 1
F
9/2 are taken into account. The limitations of the rate-equation approach are examined with a focus on the underlying dynamics
of this rare-earth system. 相似文献
74.
APPLICATION OF GENETIC ALGORITHM IN PARTICLE SIZE ANALYSIS BY MULTISPECTRAL EXTINCTION MEASUREMENTS 总被引:1,自引:0,他引:1
Gerard Grhan 《中国颗粒学报》2004,2(6):235-240
Both dependent and independent model algorithms are designed with genetic algorithm (GA) to retrieve aerosol size data from multispectral extinction measurements. Compared with the traditional dependent model algorithm, e.g., simplex, GA can locate the global optimized solution instead of local ones. As an independent model algonthm, when combined with B-splines, GA gives consistent results with Chahine and Phillip-Twomey-NNLS algorithms. Numerical simulations also show that GA has high stability and good resistance to relatively higher error levels. For a population size of 50 in the present paper, the feasible ranges for genetic operators Pc and pm are found to be [0.01, 0.5] and [0.01, 0.15], respectively, and the generation number Gen_Max should be larger than 250. 相似文献
75.
LI YingQiu HU YangLi & LIU QuanSheng College of Mathematics Computing Sciences Changsha University of Science Technology Changsha China College of Mathematics Computer Sciences Hunan Normal University Changsha LMAM University of Bretgne-Sud BP Vannes France 《中国科学 数学(英文版)》2011,(7)
Let W be the limit of the normalized population size of a supercritical branching process in a varying or random environment. By an elementary method, we find sufficient conditions under which W has finite weighted moments of the form EWpl(W), where p > 1, l 0 is a concave or slowly varying function. 相似文献
76.
Oleg I. Baskakov Eugen A. Alekseev Roman A. Motiyenko Jarmo Lohilahti Veli-Matti Horneman Seppo Alanko Brenda P. Winnewisser Ivan R. Medvedev Frank C. De Lucia 《Journal of Molecular Spectroscopy》2006,240(2):188-201
High resolution FTIR spectra of the two overlapping bands ν7 and ν9 of the 13C species of formic acid have been measured and analyzed. Rotational transitions in the millimeter wave region were measured and included in the analysis. As in the parent species, there is a strong Coriolis interaction between the 71 and 91 states. The corresponding IR bands of the parent species have been remeasured and new MMW transitions recorded. The analysis of the spectra for the two species provides an opportunity to consider a reduction of the Hamiltonian employed for the analysis of this type of interacting system of states. Parameters with low correlations could be obtained. Several interstellar features coincide with transitions predicted from these parameters. 相似文献
77.
A. Perrin J. Orphal S. Klee H. Mäder M. Winnewisser 《Journal of Molecular Spectroscopy》2004,228(2):375-391
Nitric acid (HNO3) plays an important role in the Earth’s atmosphere as a reservoir molecule of NOx species. It has a strong infrared signature at 11 μm which is one of the most commonly used for the infrared retrieval of this species in the atmosphere since this spectral region coincides with an atmospheric window. It is therefore essential to have high quality spectral parameters in this spectral region. The main goal of this work is then to generate as reliable as possible line positions and intensities for the ν5 and 2ν9 cold bands centered at 879.1075 and 896.4467 cm−1, respectively. In particular the existing line parameters need improvement in the wings of the 11 μm window in order to retrieve more accurately the CFC-11 (CCl3F) and CFC-12 (CCl2F2) atmospheric species at ∼850 and ∼920 cm−1, respectively. This work is also motivated by theoretical considerations. Very strong resonances couple indeed the 51 and 92 rotational levels. In addition the ν9 mode (OH torsion) is a “large amplitude” motion, and torsional splittings affect both the v9=2 and the v5=1 rotational transitions. In the present study, these effects are accounted for simultaneously both for the line position and line intensity calculations. To calculate the line positions the Hamiltonian matrix accounts for the very strong Fermi and the weaker Coriolis interactions linking the 51⇔92 rotational levels, and the torsional effects are accounted for within the frame of the IAM (Internal Axis Method) approach. In addition, the v-diagonal blocks involve non-orthorhombic operators together with Watson’s type rotational operators. This means that the z-quantization axis deviates from the a inertial axis for both the 51 and 92 vibrational states. The line intensity calculations were performed accounting also for the axis switching effects. As far as the experimental line positions are concerned we have used the millimeter wave data available in the literature [J. Mol. Spectrosc., 175 (1996) 395; J. Mol. Spectrosc., 208 (2001) 121; and references therein], as well as new centimeter wave measurements performed in Kiel and new Fourier transform infrared spectra recorded in Giessen. For the line intensities we have used an extensive set of individual line intensities measured recently [J. Mol. Spectrosc., 218 (2003) 151]. All these experimental data were very satisfactorily reproduced using the theoretical model described above and an improved set of line positions and intensities was generated for the ν5 and 2ν9 bands allowing one to better model the HNO3 absorption in the 11 μm spectral domain. 相似文献
78.
Marie Šime?ková Ulrike Fuchs Gisbert Winnewisser Koichi M.T. Yamada 《Journal of Molecular Spectroscopy》2004,226(2):123-136
The rotational spectrum of methylcyanide (acetonitrile) in the ground vibrational state was measured in the spectral region from 91 to 810 GHz using the Cologne and Tsukuba spectrometers operated in the Doppler-limited and sub-Doppler saturation layouts. The resolution of the saturation Lamb-dip measurements is estimated to be about 1 kHz at the best of circumstances and the measuring accuracy of 10-60 kHz depending very sensitively on the quality of the spectrum. In the cases of rotational transitions with the low quantum number J (J<18) and with a low difference of the rotational quantum numbers J−K, the resolved or partly resolved hyperfine structures of the rotational transitions were observed. Together with the most accurate data from the literature, the newly measured experimental data were analyzed using the traditional polynomial energy formula as well as the Padè approximant for the effective rotational Hamiltonian. The resulting rotational, centrifugal distortion, and hyperfine structure spectroscopic constants were obtained with a significantly higher accuracy than the ones listed in the literature. In addition, an anomalous accidental resonance was detected between the K=14 ground state levels and the K=12, +l levels in the excited v8=1 vibrational state. 相似文献
79.
Z. Zelinger T. Amano V. Ahrens S. Brünken F. Lewen H.S.P. Müller G. Winnewisser 《Journal of Molecular Spectroscopy》2003,220(2):223-233
Measurements of the rotational spectrum of HCN in excited vibrational states have been extended to higher-J values. The transitions reach J=8←7 around 710 GHz for most vibrational states studied in this investigation and J=22←21 near 2 THz for the (020) and (030) vibrational states. Using a pure sample of gaseous HCN at 350 K, selected states up to one quantum in the C–H stretching vibration at 3311.5 cm−1 have been investigated. Even transitions having two quanta in the C–H stretch could be studied employing a glow discharge in a gas mixture of CH4 and N2. Molecular constants in 13 vibrational states have been obtained, several of which have been studied for the first time by rotational spectroscopy. The vibrational temperature in the discharge system is found to be about 1500 K for the stretching vibrational modes and about 600 K for the bending states. 相似文献
80.
L.A. Surin A.V. Potapov V.A. Panfilov B.S. Dumesh G. Winnewisser 《Journal of Molecular Spectroscopy》2005,230(2):149-152
The b-type rotational transitions of the van der Waals complex, Ne–CO have been measured using the intracavity OROTRON jet spectrometer in the frequency range of 80–115 GHz. The high sensitivity of this technique enabled us to detect all three Ne isotopic modifications of the complex, 20Ne–CO, 22Ne–CO, and 21Ne–CO in natural abundance. The observed and assigned transitions belong to the Q-branch of the K = 1–0 subband and include also R (0) and P (2) lines. The newly obtained data were analysed together with previously observed millimeter-wave b-type and microwave a-type rotational transitions. 相似文献