共查询到20条相似文献,搜索用时 15 毫秒
1.
A tunable single-mode stabilized CO2 TEA laser is used to optically pump D2O vapour. Two D2O absorption lines separated from the CO2 P(32) line centre by 0.6 GHz and -1.4 GHz are found to produce respective FIR emission at 120 μ and 66 μ. Superradiant output efficiences of up to 70% of the the theoretical maximum are observed. Laser cavity operation of the two D2O emission lines was also observed with quantum conversion efficiencies of 6.8% (66 μ) and 14.5% (120 μ) when calculated for the active lasing volume. 相似文献
2.
The pump polarization has an evident effect on a superradiant FIR Raman laser both in NH3 and CH3F gases when the pump detuning from the resonant line is larger than the Raby frequency. In particular for R resonant lines the circular polarization shows a spontaneous gain about 1.5 times greater than the linear polarization as expected from the theory. 相似文献
3.
Nikolai F. Zobov Roman I. Ovsannikov Oleg L. Polyansky Andrew Janka Peter F. Bernath 《Journal of Molecular Spectroscopy》2006,240(1):112-119
An emission spectrum of hot D2O (1500 °C) has been analyzed in the 2077-4323 cm−1 region. A considerable number of new vibration-rotation energy levels have been determined and two new vibrational levels identified. The new (0 4 1) and (0 2 2) vibrational levels have estimated band origins of 7343.93 ± 0.01 and 7826.38 ± 0.02 cm−1, respectively. 相似文献
4.
Jerald R. Izatt Wen-sen Zhu 《International Journal of Infrared and Millimeter Waves》1990,11(11):1345-1354
Multi-kolowatt pulses with limited wavelength tunability have been produced in several bands between 186 and 817 m by pumping v3 P-branch transitions in12CH3F and12CD3F with the 10.6 m band of a ten-atmosphere CO2 laser. The FIR emissions are all restricted to the immediate neighborhood of the resonances associated with successive J-numbers, but there is some evidence that additional off-resonant emission could be produced with stronger pumping. The optimum operating pressure for the various molecule/J-number combinations range from 7 to 75 torr and increase rapidly with increasing J-number. 相似文献
5.
The operation of a continuous CO2 waveguide laser at nearly atmospheric pressure is reported. A plasma injection technique is used to produce a uniform discharge at atmospheric pressure. Continuous output power of 0.6 W was obtained at the inlet pressure of 800 torr. Corresponding outlet pressure was 340 torr. While the maximum output power was 1.4 W at the inlet pressure of 600 torr. The gas mix ratio was CO2 : N2 : He = 1 : 1 : 6. 相似文献
6.
The nuclear spin conversion of a molecule is the modification of the total nuclear spin I of its equivalent atoms. This phenomenon is observed by measuring the relaxation rate of a gas sample initially prepared with a population of spin isomers far from the equilibrium given by nuclear spin statistics. New experimental data obtained at low pressure show a surface-induced enhancement of the nuclear spin conversion in 13CH3F. Contrary to binary collisions in the gas phase, hitting the surface induces direct conversion. Several mechanisms are proposed. 相似文献
7.
Deuteration of the readily-exchangeable protons in [(CH3)3NH]-CoCl3·2H2O causes little or no change in the long-range magnetic ordering temperature. This is consistent with the strong two-dimensional anisotropy of exchange interactions in this chained compound. 相似文献
8.
The complete GVFF of CHF3, CH2F2, and CH3F has been calculated from self-consistent-field ab initio energies, using a 4–31 G basis set. The larger part of the interaction force constants is close to those of the best available force fields from experimental data. Only one interaction term in CH3F and the interaction force constants of the A1 species in CH2F2 differ appreciably from the experimental ones. Using constraints from the ab initio studies we have improved the GVFF of CH3F and CH2F2. It is shown that all comparable stretch-stretch interaction terms are of the same order of magnitude in the three molecules. The sign of all stretch/bend force constants are in accordance with those predicted by the hybrid orbital force field. 相似文献
9.
A theory of the saturable absorption of pulsed CO2-laser radiation by CH3F is described. It is valid for arbitrary pulse shapes and durations in the rate-equation regime. The theoretical predictions agree satisfactorily with available experimental data. The effect of vibrational exchange and the influence of the Boltzmann population factor on transmission are discussed. 相似文献
10.
Stark tuned level crossing resonances have been detected in CH3F through non-linear microwave absorption. In our experiments, the level crossing width is about ten times smaller than the Doppler width. 相似文献
11.
John R. Tucker 《Optics Communications》1976,16(2):209-212
A time dependent, rate equation model is proposed to describe the main features of pump absorption and gain in pulsed CH3F lasers. The agreement with recent absorption and output power measurements indicates that the concepts derived from this theory are relevant to the design of more efficient pulsed FIR sources. 相似文献
12.
J.A. Mucha D.A. Jennings K.M. Evenson J.T. Hougen 《Journal of Molecular Spectroscopy》1977,68(1):122-124
Laser magnetic resonance rotational spectra of the free radical CH2F have been obtained using far-infrared laser lines at 301.3, 393.6, 513.0, and 567.9 μm. The radical was prepared under fast-flow conditions by fluorine atom abstraction of a hydrogen from methyl fluoride and by fluorine atom addition to diazomethane. The spectra obtained are too crowded and overlapped to permit significant spectroscopic analysis, but they do support a planar C2v structure for CH2F and lead to a value of (B + C) = 1.953 ± 0.015 cm?1. 相似文献
13.
Infrared intensity analysis was done in two ways. In one approach, formulas connecting electrooptical parameters (eop's) and intensities were derived and, using the intensities, the former were obtained. In evaluating the eop's the intensity sum equations were used directly so that the sign ambiguity of is avoided. In the other method, polar tensors were obtained directly from intensities. The two methods have now been connected, and polar tensors have been obtained in terms of electrooptical parameters so that the former were also free from sign ambiguity of . They compare well with those obtained directly from intensities. In similar connecting formulas by other authors [see, for example, P. L. Prasad, J. Chem. Phys., 69, 4403, (1978)], both polar tensors and eop's were affected by the sign ambiguity. 相似文献
14.
The regions around the respective carbon, nitrogen and oxygen K-edges of CH4, NH3, H2O, CH3OH, CH3OCH3 and CH3NH2 have been investigated by electron energy loss spectroscopy using a beam of 2.5 keV electrons. All spectra show a number of discrete peaks just below the K-shell ionization threshold. These discrete structures have been interpreted as being associated with the promotion of a K-shell electron to Rydberg orbitals which converge to the K-shell ionization threshold. 相似文献
15.
P. B. Davies Yuyan Liu Zhuan Liu 《International Journal of Infrared and Millimeter Waves》1993,14(12):2395-2400
Twenty-seven new cw far infrared laser lines with wavelengths between 137 and 988m have been observed from optically pumping C2H3F, C2H3Cl, C2H3Br, C2H5F, C2H3CN, CH2CF2, HCOOH and CH3Br with a CO2 laser. The wavelengths of these FIR laser lines were determined together with their optimum pressures and relative intensities. 相似文献
16.
Shuichi Yamazaki Shun-Ichi Ikawa Masao Kimura 《Journal of Quantitative Spectroscopy & Radiative Transfer》1980,24(5):421-426
Far-i.r. absorption intensities have been measured for H2O and D2O in C6H6 solutions. Beer's law plots were found to be nonlinear. From the plots, the equilibrium constants of dimer formation in benzene were estimated to be 2.4M-1 and 3.3M-1 for H2O and D2O at 20°C, respectively. Based on Onsager's reaction field and including explicitly the effect of differences in molecular size between solute and solvent molecules, the internal moment of a water molecule and the volume ratio of a molecule to a cavity were estimated from the integrated absorption intensity of a D2O monomer in C6H6 as 1.98 D and 0.7, respectively 相似文献
17.
V. A. Batanov V. B. Fleurov O. M. Khlebnikov K. Yu. Kuzmin I. A. Lesnov A. O. Radkevich S. V. Timofeev A. Yu. Volkov 《International Journal of Infrared and Millimeter Waves》1990,11(3):435-442
Conclusion The compact superradiant FIR laser is developed using Herriott cell with long optical path as a FIR cell. The employment of the multipass cell gave an opportunity to increase the IR to FIR conversion efficiency in comparison with traditionally constructed FIR lasers and to observe many intensive FIR lines. The given of multipass cell can be useful for employment in continuously tunable FIR lasers. 相似文献
18.
B.L. Yu 《Optics Communications》2006,258(2):256-263
The absorption spectrum of D2O vapor from 0.2 to 2.0 THz (6.7-67 cm−1) which is associated with rotational modes was measured at one atmosphere using terahertz time-domain spectroscopy (THz-TDS). The linewidth and collisional dephasing times were measured for 26 pure rotational transitions in the ground vibrational state (0 0 0). The temperature dependence of the linewidth (Δν) behaves as Δν ∼ T−3/4 and the linewidth decrease with increasing temperature is attributed to the 1/r6 force of interaction between colliding D2O molecules. 相似文献
19.
The (2,0,1) ← (0,0,0) rovibrational transitions of D2O in the near infrared region were measured with a resolution of 0.07 cm−1using photoacoustic laser absorption spectroscopy. We report on the assignment of newly observed transitions and determine new inertial and centrifugal constants of D2O (2,0,1) using the Watson-type A-reduced Hamiltonian for asymmetric tops. 相似文献
20.
C.T. Reimann J.W. Boring R.E. Johnson J.W. Garrett K.R. Farmer W.L. Brown K.J. Marcantonio W.M. Augustyniak 《Surface science》1984,147(1):227-240
Studies of molecules ejected from water ice by fast ions provide insight into the electronic relaxation processes and subsequent chemistry occurring in ice at very low temperatures. The ion-induced ejection of D2O, D2, and O2 molecules from thin films of D2O ice has been measured as a function of the fluence of incident MeV ions at temperatures between 10 and 140 K. For a given beam current, the O2 yield exhibits initial transients which are slow compared with the prompt ejection of D2O. We interpret these results as due to the build-up of O2 in the films following fragmentation of D2O molecules by incident ions. The fragmens re-form into new molecular species which diffuse to and escape from the surface, aided by subsequent bombardment. The D2 transient has a prompt component, which we postulate is due to rapid formation during electronic recombination near the surface. A slow component of the D2 transient is also observed, which may arise through a two-step process similar to that of O2. Time-of-flight energy spectra of the ejected D2O molecules have also been measured. Incident ion masses and energies range from those for which nuclear elastic energy deposition dominates (50 keV argon) to those for which electronic energy deposition dominates (1.5 MeV helium). The spectra cannot be described by models typically employed for the sputtering of metals. For instance, the spectra do not have maxima characteristic of the sublimation energy of the solid. In addition, the sputtering yield in the high energy part of the ejection spectrum of D2O is too large to arise from nuclear elastic energy deposition. It must result instead from relatively energetic non-radiative relaxation of electronic excitation. For incident MeV ions that deposit their energy predominantly in electronic excitation, the low energy part of the D2O ejection spectrum is greatly enhanced, indicative of a weakly antibinding region formed along an incident particle track. Enhanced ion yields are also found in the collision cascade region which are attributed to electronic processes. 相似文献