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21.
Transitions between the spin-rotational levels of the 12CH radical in the v = 1 level of the X2Π state have been studied by the technique of laser magnetic resonance at far-infrared wavelengths. The data have been combined with a measurement of lambda-doubling transition frequencies at 7 GHz to determine an improved set of molecular parameters for CH in the v = 1 level. The parameters provide information on the effects of vibrational excitation on the structural properties of CH. Accurate predictions of the transition frequencies between the low-lying levels of the radical in the absence of a magnetic field have also been made.Small inconsistencies in the least-squares fit of the laser magnetic resonance data prompted re-measurement of three far-infrared laser frequencies, the 122.5 μm line of CH2F2 pumped by 9R(22), the 122.5 μm line of CH2F2 pumped by 9P(8) and the 554.4 μm line of CH2CF2 pumped by 10P(14). The new measurements differ by as much as 3.8 MHz from those made previously and are more accurate; they also remove the inconsistencies in the fit. The re-measured frequencies of the two 122.5 μm lines are identical within experimental error which suggests that the far-infrared lasing transition is the same, namely the rR23(32) transition in the v9=1 level of CH2F2. 相似文献
22.
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
23.
We studied the far-infrared emission spectrum resulting from recombination of an electron with an ionized impurity of As and
Sb in germanium under impact ionization at liquid, helium temperatures. The emission peaks at the position corresponding to
the transition from the 2p
± excited state to the ground state. This observation indicates that recombination occurs through the capture by the excited
states of the donor impurity, which is consistent with the cascade trap model. The intensity of emission radiation is of the
order of 10−7 watts for the excitation power of about one watt, which implies a dominant process of recombination to be accompanied by
phonon emission. 相似文献
24.
25.
I. Mukhopadhyay R. M. Lees J. W. C. Johns 《International Journal of Infrared and Millimeter Waves》1988,9(12):1119-1140
The high-resolution far-infrared (FIR) Fourier transform spectrum of13CH3OH has been studied from 25–350 cm–1, andb-typerR-branches in the torsional ground state have been assigned. The branches have been fitted to phenomeno-logical expansion parameters, which reproduce the branch frequencies generally to well within ±0.001 cm–1. An interesting and relatively novel K=4 perturbation, localized to levels around J=18, has been observed between (nK)=(019) and (125) states. 相似文献
26.
FISICA (Far-Infrared Space Interferometer Critical Assessment) was a three year study of a far-infrared spatio-spectral double-Fourier interferometer concept. One of the aims of the FISICA study was to set-out a baseline optical design for such a system, and to use a model of the system to simulate realistic telescope beams for use with an end-to-end instrument simulator. This paper describes a two-telescope (and hub) baseline optical design that fulfils the requirements of the FISICA science case, while minimising the optical mass of the system. A number of different modelling techniques were required for the analysis: fast approximate simulation tools such as ray tracing and Gaussian beam methods were employed for initial analysis, with GRASP physical optics used for higher accuracy in the final analysis. Results are shown for the predicted far-field patterns of the telescope primary mirrors under illumination by smooth walled rectangular feed horns. Far-field patterns for both on-axis and off-axis detectors are presented and discussed. 相似文献
27.
R. Tesa? J. Kolá?ek Z. Šimša M. Šindler L. Skrbek K. Il’in M. Siegel 《Physica C: Superconductivity and its Applications》2010,470(19):932-934
Transmission of terahertz waves through a thin layer of the NbN superconductor deposited on a sapphire substrate was studied as a function of temperature in zero field as well as in magnetic field perpendicular to the sample. For photon energies lower than optical gap, detailed temperature measurements in zero field provide BCS-like curves with a pronounced peak below the critical temperature. In accordance with the BCS model, the temperature peak disappears as the energy of incident radiation is increased above the gap. In non-zero field, the temperature behavior of transmission is modified because the gap is suppressed and vanishes at upper critical field. In addition, the presence of quantized vortices in the superconducting film substantially changes shape of the temperature curves. 相似文献
28.
Two clay minerals from the kaolin group, namely well-ordered kaolinite and poorly ordered halloysite, were investigated by terahertz time-domain spectroscopy (THz-TDS). Both clay samples were used for preparation of their respective intercalates using dimethyl sulfoxide (DMSO) and potassium acetate (KAc) with water. The intercalates were also characterized by X-ray powder diffraction and Fourier transform infrared spectroscopy. The dielectric behaviour of clay samples was investigated in the far-infrared region of 0.2–2.7 THz corresponding to about 6.7–89.9 cm−1. The frequency dependence of the power absorption coefficient revealed clear absorption bands for DMSO intercalates but not for KAc with water. For kaolinite – DMSO intercalate a distinct doublet at 1.70 THz (56.6 cm−1) and 1.88 THz (62.6 cm−1), and for halloysite – DMSO intercalate a single broad band centred around 1.72 THz (57.3 cm−1) were found. These bands are reported for the first time in this type of intercalation substances and indicate the application potential of THz time-domain spectroscopy for use in the investigation and detection of chemical behaviour of molecular species introduced into the interlayer space of layered substances such as clays and clay minerals. Additionally, the qualitative characteristics of observed bands of DMSO intercalates in the THz region reasonably resembled the structural order/disorder of used kaolinite and halloysite samples. 相似文献
29.
Far-infrared and millimeter wave spectra of copper ion conducting crystal RbCu4Cl3+xI2−x, which has the same structure as the room temperature silver ion conductor RbAg4I5, were investigated. Broad absorption peaks observed around 40, 80, and 110–200 cm−1 at room temperature show doublet structures at low temperature; this may be attributed to the difference of local structure by chlorine and iodine ion. The 110–200 cm−1 bands seem to be symmetric breathing modes of CuX4 (X = Cl or I) tetrahedron and the frequency shift coincides with the square root of the mass ratio of conduction ions. The 80 cm−1 band seems to be Rb-X vibration in RbX6 octahedron. The 40 cm−1 band seems to be the attempt mode which is an outward motion of the mobile ion in halogen cage. The increase of the absorption intensity at the low energy side with temperature corresponds to an increase of the DC conductivity. Plasmon fitting in energy loss function spectra was attempted. 相似文献
30.
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