We can hardly expect substantial intermolecular interactions in these substances. Lasing Cutoff Mechanism; Simplified Laser-Level Diagram. Population Dynamics of the Upper Laser Levels in the 1+ Band System of N2 -- 8. Dependence of the Width and Shape of the Giant Pulse on the Population Inversion Coefficient. In this case the probability of finding an atom in excited states decreases exponentially with time and, consequently, the spontaneous emission line has a dispersion form. Self Mode Locking in a Solid-State Laser Using a Bleachable Filter.
The Oriented Gas Model and its Application to Molecular Crystals polarization diagrams of luminescence. These vibrations have been quantitatively described by a set of dispersion parameters. Such a relationship between the line widths and transition frequencies allows the use of the so-called two-level scheme. For studying the rotational oscillations of the methyl groups in the low-frequency Raman spectrum we considered that methyl-substituted cyclohexanes constituted a good type of sample. Possible Mechanisms of the Formation of Negative-Temperature States in the Pinch-Discharge Plasma.
The results of the measurements and a study of crystals having a near-perovskite structure see Chapter V have enabled us to draw some conclusions regarding the form of the normal modes found. This means that the system of equations 7. In addition to the experimental problems there are fundamental difficulties associated with the impracticality of many of the methods based on the presumed existence of thermodynamic equilibrium. Determination of the Parameters of the Pinch-Discharge Plasma. Measurements of the electron temperature according to the plasma conductivity are the most reliable at high degrees of ionization. This property is caused by a certain singularity in the formation of the giant pulse in a laser with a passive shutter, being attributable to the fact that the formation period, measured from the time at which the gain in the active medium offsets the cavity losses to the instant at which the pulse intensity attains its peak value, is considerably larger than for other types of shutters. Pulsed lasing associated with electron transitions in diatomic molecules at the leading edge of a power ful current pulse in a gas is subjected to systematic analysis.
Thus, radiative excitation can be entirely neglected due to the small optical thickness of the medium in gas lasers. Large-wavelength lasing could not be observed on our equipment, because the detectors had practically zero sensitivity in the system. Moreover, the accumulation effect is quite strong and this effect sometimes prevents the measurement of the field effect because the surface conductivity minimum cannot be reached. The times characterizing the development of the processes involved in pinch are on the order of 10-8 to 10-7 sec. The only exceptions are the F2u Oh vibration? Lasers generate simultaneously several quasi-monochromatic lines corresponding to different oscillation modes which have natural frequencies within the width of the spontaneous emission line. As a result of the successful development of research methods and the widespread applica tion of vibrational spectra in analyzing the structures of molecules and the constitution of ma terials, it now becomes necessary to develop the theory of molecular vibrations further. A weak field, in contrast to a strong one, is a field which does not affect the mean populations of the levels m, n.
Dependence of the Width and Shape of the Giant Pulse on the Population Inversion Coefficient. Hence, a study of the vibrational spectrum of this hydrocarbon is of great significance for understanding the structure of the molecules in other six-membered naphthenes. Description of the Experimental Setup. Existing theory, of course, is based on the assumption of the harmonicity of molecular vi brations, which, strictly speaking, is not justified experimentally. The passive shutter, however, also has its own specific peculiarities, which distinguish it from other types of shutters.
As a rule, the breakdown in this case occurs in a long cylindrical tube at a low gas pressure ~ 1 mm Hg in a strongly inhomogeneous field and at relatively high overvoltages. Dependence of the Width and Shape of the Giant Pulse on the Population Inversion Coefficient. They are transparent over a wide spectral range, including the whole visible and near-infrared regions as well as a considerable part of the ultraviolet spectrum, and they have lattices of the purely ionic type, crystallizing in the cubic system. We mentioned in Chapter I that certain characteristics of a giant pulse emitted by a laser with a passive shutter are well accounted for on the basis of the theory of lasers with an instantaneous shutter. Markin Introduction 1 Chapter 1. Spectral Composition of Solid-State Laser Emission and Mode Discrimination by Various Cavity Elements.
Elementary Quantitative Theory of Laser Action in the 1+ Band System of N2. High-Speed Photoscanning of Pinch Radiation. The apparatus had a dispersion of 4. In this chapter, we shall calculate the imaginary part of the permittivity of a lattice containing charged defects. Experimental Methodological Problems -- 3.
Elementary Quantitative Theory of Laser Action in the 1+ Band System of N2. A similar result was obtained for antimonous anhydride. The use of any method in this case requires special substantiation. In this chapter, we shall calculate the complex polarizability of an ideal ionic lattice, including anharmonic terms of the third and foruth order in its Hamiltonian. This work was stimulated by the lack of data on the spatial and temporal development of generation, despite the obvious importance of such data in the use of giant light pulses in in vestigations of the nonlinear interaction of radiation and matter.
In the presence of mechanical anharmonicity the concept of normal coordinates and normal vibrations loses its meaning. However, as a result of the anharmonicity of the vibrations, the values of the observed frequencies differ from the harmonic values, and the force constants used therefore differ from the true ones, i. It is well known that cyclohexane is the simplest representative of the six-member naph-thenes, an important class of hydrocarbons. Two methods are now used for recording Raman spectra: photographic and photoelectric. The general pattern of development of pulsed discharge under the conditions named above, however, is not clear at the present time. According to these studies the emission spectrum of the laser must consist of separate, equally spaced components, or modes here and elsewhere we are concerned only with axial modes, i.