共查询到20条相似文献,搜索用时 15 毫秒
1.
Jiayin Qin Xizhang Luo Jiang Xiao Xiao Huang Ruman Qiu 《International Journal of Infrared and Millimeter Waves》1999,20(5):783-789
In this paper, the density matrix equation of three-level system for far-infrared (FIR) Raman transition in vibrational ground state was solved. By means of iteration method and numerical calculation, the spectral characteristics of NH3 molecules FIR laser with TEA CO2-10R(14) laser pumping was studied theoretically. The theoretical result would help us to understand the physical mechanism of optically pumped molecular gases FIR laser with ground-state reversal transition. 相似文献
2.
G. R. Sudhakaran B. J. Soller M. Jackson I. Mukhopadhyay R. M. Lees 《International Journal of Infrared and Millimeter Waves》1995,16(12):2111-2131
The high resolution laser Stark spectra of methanol and13C-substituted methanol have been studied up to Stark fields of about 60 000V/cm with the HCN and DCN lasers. Numerous families of absorption lines have been observed in both parallel and perpendicular polarizations. For methanol, the transitions J
k
=75 64 A,
t=0; J
k
=114 103 E
l
,
t=0; and J
k
=173 162 E2,
t=0 have been identified while the assignments for13C-substituted methanol are J
k
=148 157 A,
t=0; J
k
=153 142 A+,
t=0; J
k
=107 96 A,
t=0; and J
k
=279 278 E1,
t=0. Zero-field frequencies for the assigned transitions are given with improved accuracy over those calculated from available molecular constants, especially for13CH3OH. 相似文献
3.
Pierre Bernard Jerald R. Izatt Pierre Mathieu 《International Journal of Infrared and Millimeter Waves》1981,2(1):65-70
Using a grating-tuned CO2-TEA laser to pump CH3OH in a metallic-wave-guide resonator, submillimeter laser emissions have been produced by pumping with 36 lines in the 9.4m CO2 band and with 23 lines in the 10.6m band. Several dozen new SMM laser lines were observed. Wavelengths accurate to within 0.1% are given for 12 previously unmeasured lines between 34m and 225m. 相似文献
4.
G. Moruzzi J. C. Silos Moraes F. Strumia 《International Journal of Infrared and Millimeter Waves》1992,13(9):1269-1312
Methyl alcohol is the most important lasing molecule in the Far-Infrared (FIR) spectral region, and the most widely used for investigation and for applications. Since the last critical review of 1984, over seventy papers have been published dealing with the FIR laser lines and the infrared spectroscopy of CH3OH. In 1984 we could list about 330 FIR laser lines, 98 of which were measured in frequency and 105 assigned. Since then more than 70 papers were published increasing the number of the known laser lines to 575 (103 measured in frequency). Also the FIR and IR spectroscopy was largely improved thanks to the analysis of high resolution FT spectra, and the number of the correctly assigned laser lines has been increased to 224. The wavenumbers of the assigned lines can now be predicted with an accuracy of about 0.001 cm–1 or better, thus approaching the accuracy of the experimental frequency measurements. 相似文献
5.
M. Jackson G. R. Sudhakaran A. Silveira Jr. I. Mukhopadhyay R. M. Lees 《International Journal of Infrared and Millimeter Waves》1999,20(4):583-594
The high resolution Stark spectra of the singly deuterated methanol isotope, CH3OD, have been studied using the HCN laser with Stark fields up to approximately 60 000 V/cm. Numerous families of absorption lines have been observed in both parallel and perpendicular polarizations, resulting in the following assignments: with the 311 m line – J
K = 181 180
E
2,
t = 1; and with the 337 m line – J
k = 64 53
E
2,
t = 0 and J
K = 146 135
A,
t = 1. Zero-field frequencies for the assigned transitions are in agreement with Fourier transform measurements and those calculated from the available molecular constants. 相似文献
6.
G. Carelli N. Ioli A. Moretti G. Moruzzi D. Pereira F. Strumia 《International Journal of Infrared and Millimeter Waves》1991,12(5):449-471
We have increased the frequency tunability of our CW waveguide CO2 lasers by means of an acoustooptic amplitude modulator, operating at the fixed frequency of 90 MHz. The up-shifted, or down-shifted, laser optical sideband can be generated independently by adjusting the orientation of the modulator. The efficiency is larger than 50%. The frequency tunability of the CO2 laser around each laser line is thus increased by 180 MHz. To demonstrate the possibilities of this method, a source composed of the above modulator and of a CW, 300 MHz tunable waveguide CO2 laser has been used for the search of new large offset FIR laser lines from optically pumped CH3OH and13CH3OH molecules. As a result 15 and 10 new large offset laser lines were discovered respectively. New assignments of some laser lines are also proposed. We have also measured the Stark effect, the offset, and the polarization of other already known lines. In particular a Stark effect frequency tuning of about 1 GHz is demonstrated for a laser line at 208.399 m. 相似文献
7.
M. Ingusio A. Moretti G. Moruzzi F. Strumia 《International Journal of Infrared and Millimeter Waves》1981,2(5):943-986
An extensive theoretical and experimental analysis of the absorption and emission spectrum of a CH3OH FIR-laser excited by a conventional CO2 laser is presented. Particular interest is devoted to the Stark shifts of the pump and lasing lines and to the electric field dependence of the Fir-laser output of the various lines. The offsets with respect to the exciting radiation and the Stark shifts of the IR absorption (pump) lines are measured by means of the transferred Lamb dip technique. The theoretical behaviours of the Stark patterns are calculated for several choices of the quantum numbers and selection rules involved in the transitions. A large variety of experimental results are reported and compared to theory. Non-linear Stark shifts have been observed for the 37.5m FIR laser line and for the IR-pump transitions excited by the 9-P(38) and 10-R(38) CO2 laser Lines. Line assignments are proposed and new FIR laser lines are reported. 相似文献
8.
Xiao Huang Jiayin Qin Xingshi Zheng Yanxiang Bao Xizhang Luo Yikun Lin 《International Journal of Infrared and Millimeter Waves》1997,18(8):1539-1546
By solving the density matrix equations of a quantum system, the output power intensity of an optically pumped CH3OH FIR laser (CH3OH-OPFIRL) was calculated by means of iteration method, and the spectral characteristics were got. Base on the calculation,
optimization of operating parameters including operating gas pressure, pumped power and output coupling coefficient of the
CH3OH cavity laser were systematically studied. Experimental, a series of FIR emissions of the CH3OH cavity laser pumped by TEA-CO2 laser with 9P(16) line were measured. The experimental results were in good agreement with theoretical calculations.
The project was supported by the Special Research Foundation of Doctorate Station in University of P.R.C. 相似文献
9.
M. Yamanaka Y. Takeda S. Tanigawa A. Nishizawa N. Noda J. Fujita M. Takai M. Shimobayashi Y. Hayashi T. Koizumi K. Nagasaka S. Okajima Y. Tsunawaki A. Nagashima 《International Journal of Infrared and Millimeter Waves》1980,1(1):57-76
A twin optically-pumped far-infrared CH3OH laser has been constructed for use in plasma diagnostics. The antisymmetric doublet due to the Raman-type resonant two-photon transition is reproducibly observed at 118.8 m. With the 118.8-m line, it is obtained from the frequency separation of the anti-symmetric doublet that CH3OH absorption line center is 16±1 MHz higher than the pump 9.7-m P(36) CO2 laser line center. It is shown that the Raman-type resonant two-photon transition is useful in order to get several-MHz phase modulation for the far-infrared laser interferometer. Some preliminary performances of this twin laser for the modulated interferometer are described.This work was carried out under the collaborating research program at the Institute of Plasma Physics, Nagoya University, Nagoya 464, Japan. 相似文献
10.
Shucheng Xu 《Proceedings of the Combustion Institute》2007,31(1):159-166
Kinetics and mechanisms for reactions of OH with methanol and ethanol have been investigated at the CCSD(T)/6-311 + G(3df, 2p)//MP2/6-311 + G(3df, 2p) level of theory. The total and individual rate constants, and product branching ratios for the reactions have been computed in the temperature range 200-3000 K with variational transition state theory by including the effects of multiple reflections above the wells of their pre-reaction complexes, quantum-mechanical tunneling and hindered internal rotations. The predicted results can be represented by the expressions k1 = 4.65 × 10−20 × T2.68 exp(414/T) and k2 = 9.11 × 10−20 × T2.58 exp(748/T) cm3 molecule−1 s−1 for the CH3OH and C2H5OH reactions, respectively. These results are in reasonable agreements with available experimental data except that of OH + C2H5OH in the high temperature range. The former reaction produces 96-89% of the H2O + CH2OH products, whereas the latter process produces 98-70% of H2O + CH3CHOH and 2-21% of the H2O + CH2CH2OH products in the temperature range computed (200-3000 K). 相似文献
11.
S. C. Zerbetto L. R. Zink K. M. Evenson E. C. C. Vasconcellos 《International Journal of Infrared and Millimeter Waves》1996,17(6):1049-1054
We measured the frequencies of 12 far-infrared laser lines generated in a high- frequency Fabry-Perot laser cavity containing methanol, pumped by a CO2 laser. The frequencies are in the range 2.8 to 11.4 THz (105.4 to 26.2 µm). Ten of the measured frequencies are higher than 7 THz, and help to fill the laser frequency gaps in this region. Five of the measured lines are new. The 11.4 THz line has the highest frequency of an optically pumped laser ever measured with the CO2 laser heterodyne technique.This work has been financed by the Brazilian Government - Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), and by the United States Government - NASA Grant W-18, 623.Contribution of NIST, not subject to U.S. Copyright. 相似文献
12.
Six FIR laser lines from CD3OH pumped by the 10R(36) and the 10R(18) CO2 laser lines are assigned to specific rotational energy levels in the excited C–0 stretch state. It is found that their upper laser levels are shifted by a Fermi resonance between the C–0 stretch vibration and the third and forth harmonics of the torsional mode. The Fermi resonance shifts are +0.332 cm–1 and +2.251 cm–1 for the upper laser levels pumped by the 10R(36) and the 10R(18) CO2 laser lines, respectively. Calculated frequencies of the pump and the laser transitions agree with those of the pump CO2 laser lines and the observed FIR laser lines within estimated accuracy. 相似文献
13.
Britt Hartmann Lars Lindgren 《International Journal of Infrared and Millimeter Waves》1982,3(4):503-515
Several new submillimeter laser lines have been observed in a CH3OH submillimeter laser, optically pumped by CO2—laser radiation in a low power pulsed mode.Assignments have been suggested for a number of the lines. A few lines have wavelengths close to atmospheric water vapor absorption peaks, and can be observed only when the air path from the submillimeter resonator exit mirror to the detector is kept short or flushed with dry nitrogen. 相似文献
14.
Tetsu Kachi Masanori Fukutani Shozo Kon 《International Journal of Infrared and Millimeter Waves》1982,3(3):401-408
Fifteen laser lines from CH3OD pumped by a CO2 laser are assigned to specific rotational energy transitions. These assignments have been obtained from the approximation that, except for one constant, the molecular constants in the excited CO stretching state are same as those in the ground state. 相似文献
15.
J. O. Henningsen 《International Journal of Infrared and Millimeter Waves》1986,7(10):1605-1629
Using a quasi-CW CO2 oscillator-amplifier combination with peak power 300 Watt, we have generated FIR laser emission in weak absorption bands of CH3OH. 40 new lines are reported, and their wavelengths are measured with a relative accuracy of 5×10–5. A total of 72 lines are assigned. 34 of these involve torsional n=1, 2, and 3 states of the CO stretch and the vibrational ground state. The remaining lines are associated with the CH3-rock, OH-bend, and CH3-deformation modes. The latter are located 1460 cm–1 above the ground state, and are pumped by simultaneous vibrational excitation and torsional deexcitation. 相似文献
16.
High-resolution Fourier transform spectra of CH3OH have been investigated in the infrared region from 930 to 1450 cm−1 in order to map the torsion-rotation energy manifolds associated with the ν7 in-plane CH3 rock, the ν11 out-of-plane CH3 rock, and the ν6 OH bend. Upper-state term values have been determined from the assigned spectral subbands, and have been fitted to power-series expansions to obtain substate origins and effective B-values for the three modes. The substate origins have been grouped into related families according to systematic trends observed in the torsion-vibration energy map, but there are substantial differences from the traditional torsional patterns. There appears to be significant torsion-mediated spectral mixing, and a variety of “forbidden” torsional combination subbands with |Δυt|>1 have been observed, where υt denotes the torsional quantum number (equivalent to υ12). For example, coupling of the (υ6,υt)=(1,0) OH bend to nearby torsionally excited (υ7,υt)=(1,1) CH3-rock and (υ8,υt)=(1,1) CO-stretch states introduces (υ6,υt)=(1,0)←(0,1) subbands into the spectrum and makes the ν7+ν12−ν12 torsional hot band stronger than the ν7 fundamental. The results suggest a picture of strong coupling among the OH-bending, CH3-rocking, and CO-stretching modes that significantly modifies the traditional energy structure and raises interesting and provocative questions about the torsion-vibration identity of a number of the observed states. 相似文献
17.
We use a 13CO2 laser as optical pumping source to search for new THz laser lines generated from 13CH3OH. Nineteen new THz laser lines (also identified as far-infrared, FIR) ranging from 42.3 μm (7.1 THz) to 717.7 μm (0.42 THz) are reported. They are characterized in wavelength, offset, relative polarization, relative intensity, and optimum working pressure. We have assigned eight laser lines to specific rotational energy levels in the excited state associated with the C-O stretching mode. 相似文献
18.
N. Ioli A. Moretti F. Strumia F. D'Amato 《International Journal of Infrared and Millimeter Waves》1986,7(3):459-486
27 new, large offset, FIR laser lines from13CH3OH and one from13CD3OH have been discovered by pumping with a high tunability waveguide CW CO2 laser. Optoacoustic measurements of isotopic methyl alcohol have also been performed and the pump offsets of the new and of previously known lines have been measured and checked. Frequency tunability by Stark effect has been observed for 6 strong lines. Some assignments are discussed. 相似文献
19.
M. Inguscio S. Marchetti A. Moretti F. Strumia 《International Journal of Infrared and Millimeter Waves》1982,3(1):97-116
The optoacoustic spectrum of CH3Br around 10 m band lines of a tunable cw waveguide CO2 laser is investigated. Several new infrared absorptions are observed and most of the correspond ing molecular transitions are assigned. Far infra red laser action is reported by pumping with the same CO2 laser: pump offsets are given using the Transferred Lambs dip (TLD) technique. A new FIR laser emission is obtained and assigned. An optoacoustic Laser Stark spectroscopy technique is used to investigate off resonance infrared tran sitions. 相似文献
20.
Fourier-transform far-infrared spectra of CH318OH in the 15-470 cm−1 region have been analyzed by means of the Ritz assignment program. The far-infrared data have been combined with the literature microwave and millimeter-wave measurements in a full global fitting of the first three torsional states (νt = 0, 1, and 2) of the CH318OH ground vibrational state. The fitted dataset includes 550 microwave and millimeter-wave lines and more than 17 000 Fourier-transform transitions covering the quantum number ranges J ? 30, K ? 15, and νt ? 2. With incorporation of 79 adjustable parameters, the global fit achieved convergence with an overall weighted standard deviation of 1.072, essentially to within the assigned measurement uncertainties of ±50 kHz for almost all of the microwave and millimeter-wave lines and ±6 MHz (0.0002 cm−1) to ±15 MHz (0.0005 cm−1) for the Fourier-transform far-infrared measurements. Based on the global fit results, a database has been compiled containing transition frequencies, quantum numbers, lower state energies and transition strengths. This database will provide support for present and future astronomical studies, such as the on-going Orion surveys in preparation for the launch of the Herschel Space Observatory, in identifying isotopic methanol contributions to interstellar spectra. 相似文献