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21.
Chadwick C. Rasmussen Sulabh K. Dhanuka James F. Driscoll 《Proceedings of the Combustion Institute》2007,31(2):2505-2512
Laser-induced fluorescence of OH and CH2O was imaged to investigate the flame stabilization mechanism in a flameholder with a Mach 2.4 free stream. Ethylene was burned in a rectangular cavity with two points of injection: the aft wall and the cavity floor. When injected from the aft wall, the fuel came into immediate contact with hot combustion products from the reaction zone under the shear layer. Primary combustion occurred under the shear layer and in the aft region of the cavity volume. In contrast, when fuel was injected from the floor, a jet-driven recirculation zone of hot products near the upstream wall of the cavity served as a flameholder. The reaction then occurred on the underside of the shear layer. In conditions near lean blowout, significant changes in the flameholding mechanisms were observed. Improved CH2O fluorescence signal was obtained by taking advantage of the long fluorescence lifetime at low pressures and delaying the camera gate to reduce the background signal. 相似文献
22.
23.
We present the second part of the investigation of the high sensitivity absorption spectrum of nitrous oxide by CW-Cavity Ring Down Spectroscopy near 1.5 μm. In a first paper [A.W. Liu, S. Kassi, P. Malara, D. Romanini, V.I. Perevalov, S.A. Tashkun, S.M. Hu, A. Campargue, J. Mol. Spectrosc. 244 (2007) 33-47] devoted to the 6000-6833 cm−1 region, more than 6000 line positions of five isotopologues (14N216O, 15N14N16O, 14N15N16O, 14N217O, and 14N218O), were rovibrationally assigned to a total of 68 bands. The achieved noise equivalent absorption (αmin ∼ 2 × 10−10 cm−1) allowed for the detection of lines with intensity weaker than 2 × 10−29 cm/molecule. In this contribution, the investigated region was extended down to 5905 cm−1 and additional recordings allowed accessing small spectral sections uncovered in our preceding recordings. A deeper analysis based on the predictions of the effective Hamiltonian model has allowed assigning a total of 3149 transitions and lowering the percentage of lines left unassigned from 51% to 28%. It led to the analysis of 35, 6, 7, and 6 bands for the 14N216O, 15N14N16O, 14N15N16O, and 14N218O isotopologues, respectively. Forty-two of these 54 bands are newly observed, while the rotational analysis of the twelve others is significantly extended and improved. Most of the bands were found unperturbed and their line positions could be reproduced within the experimental uncertainty (about 1 × 10−3 cm−1). The corresponding spectroscopic parameters are reported. Local rovibrational perturbations induced by either intrapolyad or interpolyad couplings were found to affect five hot bands of 14N216O. Their detailed analysis is presented. 相似文献
24.
Free energies of transfer (ΔGt) of RibonucleaseA (RNaseA) from water to aqueous solutions of urea (4 M, 6 M and 8 M), a protein denaturing solvent as well as ΔGt of RibonucleaseA, β‐Lactoglobulin, α‐Chymotripsin and ChymotrypsinogenA from water to aqueous glycerol (10%, 20%, 30% and 40%), a protein stabilizing solvent has been dissected into cavity term [ΔGt(cav)] and interaction term [ΔGt(int)]. The interaction free energy includes all types of interactions like hard‐soft, hydrogen bonding, electrostatic, etc. The cavity forming free energies have been calculated using the standard version of scaled particle theory (SPT) with well‐reported SPT parameters. It has been found that transfer free energies of cavity terms ΔGt(cav) for native protein from water to urea‐water and water to aqueous glycerol follow almost opposite trends. This primarily indicates there may be some correlation between cavity creation energies and protein denaturing and stabilizing ability of a solvent. The results are in agreement with those obtained from preferential binding coefficient studies in these media. 相似文献
25.
La Agusu T. Idehara M. Kamada T. Hayashi V. N. Manuilov O. Dumbrajs K. Yatsui W. Jiang 《International Journal of Infrared and Millimeter Waves》2005,26(5):637-655
Designs of cavities for fundamental and high harmonic operation in Large Orbit Gyrotron (LOG) are discussed. The fundamental operation allows one to use beam currents in the range from 200 A to 300 A achieve output power of the order of 9–10 MW at frequency 143.6 GHz. Mode competition calculations show that stable oscillations in the TE1,4 mode using high beam currents are possible even with the pitch factor 1.3 which is significantly lower than the design value 1.55. For the second harmonic operation, the maximum current used for excitation of the TE2,4 mode is 60 A and the optimum magnetic field is 7.6 T. A cavity design for fourth harmonic operation using the TE4,4 mode is also presented. 相似文献
26.
A physical scheme for the implementation of quantum superdense coding has been proposed in Cavity QED. The detuned interaction
between Λ-type three-level atoms and coherent fields constitute the main superdense coding process. The quantum superdense
coding can be realized in an easier way, and the atoms are not excited during the whole process, so the effect of atomic decay
is eliminated naturally. 相似文献
27.
T. Li J. C. Carrano C. J. Eiting P. A. Grudowski D. J. H. Lambert H. K. Kwon R. D. Dupuis J. C. Campbell R. T. Tober 《Fiber and Integrated Optics》2001,20(2):125-131
A resonant-cavity-enhanced p-i-n photodetector has been designed and analyzed to operate at a wavelength of 360 nm based on the AlxGa1-xN material system. The novel approach has been adopted of using epitaxial AlN/AlxGa1-xN quarter-wave stacks as the distributed Bragg reflector that serves as the front mirror. An AlxGa1-xN absorptive filter layer is incorporated to suppress all but one resonant mode to ensure single, narrow-band operation. This device structure is projected to achieve wavelength selective, high speed, and high quantum efficiency operation in the ultraviolet. MOCVD-grown 6 1/2-pair AlN/AlxGa1-x 相似文献
28.
29.
The absorption spectrum of the 16O3 isotopologue of ozone has been recorded in the 7000-7920 cm−1 region by high sensitivity CW-Cavity Ring Down Spectroscopy. This report is devoted to the analyses of the 7065-7300 cm−1 region dominated by the ν1 + 2ν2 + 5ν3 and ν1 + 5ν2 + 3ν3 A-type bands at 7130.8 and 7286.8 cm−1 respectively. 289 transitions were assigned to the ν1 + 2ν2 + 5ν3 band. The corresponding line positions were modeled with an effective Hamiltonian involving Coriolis resonance interactions between the (1 2 5) upper state and the (4 4 0), (0 2 6) and (6 1 0) dark states, and an anharmonic resonance interaction with the (2 0 5) state. The very strong interaction (up to 50% mixing of the wavefunctions) between the (1 2 5) and (6 1 0) states leads to the observation of two extra lines of the 6ν1 + ν2 band due to a resonance intensity transfer. 213 transitions of the ν1 + 5ν2 + 3ν3 band were assigned and modeled taking into account a Coriolis resonance interaction with the (3 6 0) state.We take the opportunity of the present work to report the analysis of the very weak 4ν2 + 4ν3 B-type band at 6506.1 cm−1 which was assigned from previously recorded CRDS spectra. 286 transitions were modeled using the effective Hamiltonian approach.The dipole transition moment parameters of the three analyzed bands were determined by a least-squares fit to the measured line intensities. For the three studied band systems, the effective Hamiltonian and transition moment operator parameters were used to generate line lists provided as Supplementary Materials. 相似文献
30.
The dyad bands of near 790 nm have been recorded with a continuous-wave cavity ring-down spectrometer. Two cold bands and the two associated hot bands are observed in this region. High sensitivity of the 1×10−10/cm level allows one to detect weak transitions with satisfied accuracy. The absolute line intensities have also been retrieved with an estimated accuracy of 2% for majority of the unblended lines. The vibrational transition dipole moment squared values and the empirical Herman-Wallis coefficients are presented for two cold bands. The comparison of the retrieved line positions and intensities with those given in the Carbon Dioxide Spectroscopic Databank shows clear deviation and indicates the empirical calculation can be further improved using the present spectroscopy data. 相似文献