On the anomalies in submillimeter absorption spectrum of atmospheric water vapor

Using a tunable source of monochromatic radiation (BWO) and a pneumatic detector, the field and laboratory investigations have been performed to obtain spectral distribution of atmospheric water vapor absorption coefficient in transparent windows centered at the wavelengths of 0.88 and 0.73 mm.The measurements have not found any spectral features mentioned repeatedly in the literature, besides the usually observed excess of the measured absorption above the calculated one for water vapor monomers.     

On the anomalies and role of water clusters in atmospheric absorption of millimeter and submillimeter radio waves

Experimental data are presented which do not confirm the existence of anomalies observed by many investigators in the atmospheric absorption of millimeter and submillimeter radio waves and make questionable the hypothesis on the importance of large water clusters in absorption that is invoked to explain the anomalies.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 4, pp. 483–495, April, 1996.This work was supported in part by the Russian Foundation for Fundamental Research under Project No. 94-02-05407-a).     

On infrasound radiation of shallow water waves

Sound waves generated by low-frequency gravity modes have been studied. It has been shown that the response function is inversely proportional to the fourth power of the wave number.     

Absorption of millimeter to submillimeter waves by atmospheric water molecules

Using the values of the rotational molecular parameters (including cencrifugal distortion terms) of the H₂ ¹⁶O molecule, which can explain 12 observed transitions below 800 GHz, all rotational energy levels with normalized Boltzmann factors larger than 5×10^–8 at 300°K are calculated. Probabilities of all possible electric dipole transitions among these states, 2277 lines, are calculated using the eigenfunctions thus obtained, and the permanent electric dipole moment of 1.8546 Debye. Assuming the single and full Lorentzian line forms, we calculated the absorption coefficient for millimeter to submillimeter region. Our result, using the single term Lorentzian line form, agrees quite well with experiment for 1 Torr of water vapor in 760 Torr air at 300°K.     

Investigation of iron borate on the submillimeter waves

Antiferromagnetic resonance (AFMR) in iron borate at the frequency of 300 GHz at the room temperature in weak (down to 0.1T) external magnetic fieldH has been studied. The loss in AFMR line increased or decreased depending on the direction and magnitude ofH. Such properties ofFeBO ₃ monocrystals allows to design undirectional and modulation devices.     

Fractal properties of the vibrational-rotational absorption bands of water vapor

The vibrational-rotational bands in the absorption spectra of atmospheric water vapor are interpreted using multifractal analysis. The fractal properties of the frequency distribution of absorption lines are considered, as well as “the absorption density”—the total absorption within a small frequency interval normalized to the total absorption in the region of the vibrational-rotational band. It is shown that the vibrational-rotational absorption bands of atmospheric water vapor exhibit specific multifractal characteristics.     

Investigation of water decomposition by vacuum ultraviolet radiation

The concentrations of products of liquid and gaseous water decomposition under the action of VUV (7n = 172 nm) radiation are calculated. It is shown that the VUV radiation causes efficient formation of highly reactive *OH radicals. The application the products of water photodecomposition is exemplified by the possibility of degradation of polychlorinated biphenyl upon interaction with these products.     

Estimate of lacunarity of vibrational-rotational absorption spectra of water vapor

Optical spectra of vibrational-rotational absorption bands of atmospheric water vapor are interpreted in terms of fractal analysis. The main calculation parameter is the lacunarity of the initial spectrum. The variation in the lacunarity makes it possible to estimate the degree of translational and scale invariance of the entire spectrum as some quasi-random frequency function.     

Pulsed wideband orotrons of millimeter and submillimeter waves

We have developed a series of low-voltage orotrons operated in the short-wave part of the millimeter and long-wave section of the submillimeter wavelength range. The use of an open resonator as the electrodynamic system of the orotron ensures high stability of the radiation frequency and a wide band of frequency tuning. The output orotron power achieved experimentally amounts to hundreds of milliwatts, which is sufficient for many promising spectroscopy methods. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 11, pp. 958–963, November 2006.     

Excitonic detectors of infrared and submillimeter radiation

The theory of new type detectors based on the quenching of secondary emission in direct-gap semiconductors (lines of Raman light scattering due to interaction between free and bound excitons in the crystal, and also bands of edge radiation) caused by IR or submillimeter radiation is proposed. The results obtained are confirmed by the experiment performed for CdS crystal excited by ultraviolet radiation of mercury lamp, at liquid helium temperature.     

Opacity effect on extreme ultraviolet radiation from laser-produced tin plasmas

Opacity effects on extreme ultraviolet (EUV) emission from laser-produced tin (Sn) plasma have been experimentally investigated. An absorption spectrum of a uniform Sn plasma generated by thermal x rays has been measured in the EUV range (9-19 nm wavelength) for the first time. Experimental results indicate that control of the optical depth of the laser-produced Sn plasma is essential for obtaining high conversion to 13.5 nm-wavelength EUV radiation; 1.8% of the conversion efficiency was attained with the use of 2.2 ns laser pulses.