Effect of the Parameters of Three-Mirror Resonators on the Spectral Characteristics of Single-Pulse Laser Generation with Self-Injection of Priming Radiation

Based on a semiclassical theory, investigations were made of the dynamics and spectral composition of pulsed generation with self-injection of priming radiation from the active part of a three-mirror linear resonator, the passive part of which contains an active loss modulator and serves as the output reflector of the laser. It is shown that there exists a range of resonator parameters at which pulsed lasing has virtually a single frequency irrespective of the detuning of the frequencies of the priming radiation and of the nearest eigenmode of the composite resonator. Considering graphically the phase conditions of generation, it is established that among pulsed lasers with self-injection of priming radiation which are constructed on the basis of three-mirror linear and branched resonators, the most efficient for creating single-frequency generation are those in which the length of the main resonator, where generation of the pulse occurs, is larger than the length of the additional one intended for forming the priming radiation. With an inverse ratio of the lengths of the resonators, the conditions of single-frequency pulsed generation becomes dependent on the priming radiation frequency.     

Reaction of 2-formyl-1,3-cyclohexanediones with cyanoacetamide

Chemistry of Heterocyclic Compounds -     

Synthesis and electronic absorption spectra of substituted tetrabenzoporphins

Zinc complexes of tetrabenzoporphins with substituents in the benzene fragments of the molecule were synthesized by the template tetramerization of substituted 3-carboxymethylphthalimidines or phthalimides with malonic or phenylacetic acid in the presence of zinc acetate, as well as by substitution reactions in the tetrabenzoporphin molecule. The metal-free compounds were obtained from the corresponding zinc complexes by the action of a stream of hydrogen chloride in chloroform. The electronic absorption spectra of the synthesized compounds were investigated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 773–779, June, 1988.     

Carbon suboxide and some of its reactions

The reaction of carbon suboxide with a number of 2-amino-1,3,4-thiadiazoles has given the corresponding pyrimido[1,2-b]-1,3,4-thiadiazoles     

Dynamics of generation of a pulsed Nd<Superscript>3+</Superscript>:KGd(WO)<Subscript>2</Subscript>/V<Superscript>3+</Superscript>:YAG laser emitting in the self-frequency Raman conversion mode at λ = 1.538 μm

It has been shown that the generation of the 1st Stokes component (λ = 1.538 μm) in an Nd:KGW laser with a passive V:YAG Q Q -switch is multimodal and its dynamics have a complex spatio-temporal character. The SRS-generation features the impact excitation manifested as the formation of a high-intensity peak at the beginning of the pulse, the peak position relative to the subsequent part of the pulse depending on the radius of curvature of the end cavity mirror. The SRS-conversion of the fundamental laser radiation (λ = 1.351 μm) starts in the central region of the Nd:KGW-element and then spreads towards its boundaries. The total integral SRS-pulse of duration 15–25 ns represents an envelope of shorter (1–2 ns) time-shifted pulses generated by separate local areas of the active medium cross-section. The multimode character of generation results in gradual damage to the V:YAG Q Q -switch at the attained SRS-radiation energy of 8–14 mJ.     

Synthesis of meso-tetraalkyltetrabenzoporphines

Stable complexes of zinc meso-tetralkyltetrabenzoporphines with tribenzylamine have been obtained by the template tetramerization of 3-R-methylenephthalimidines with zinc acetate in the presence of tribenzylamine or by the reaction of potassium phthalimide with the corresponding alkylmalonic acids. The structures of the compounds synthesized have been confirmed by their electronic absorption spectra, and in some cases also by their mass spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 61–64, January, 1984.     

Indoles

Derivatives of 2,3,3a,8a-tetrahydro-3a,8a-dimethylfuro[2,3-c]indole were synthesized by the reaction of arylhydrazine salts with 3-methylpentan-4-on-1-ol on heating the components in dimethylformamide.See [9] for Communication XV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1631–1633, December, 1970.     

Triplet-triplet absorption spectra of meso-tetraphenyl-2,3-tetranaphtho-2,3-tetraphenanthroporphins

Flash photolysis has been used to measure triplet-triplet (T-T) absorption spectra of meso-tetrapheny1-2,3-tetranaphthorphin and its zinc complex, and also zinc complexes of two isomers of meso-tetrapheny1-2,3-tetraphenanthrenopurphin. An analysis has been made of the inf Iuence of structural changes on the T-T absorption spectra.Institute of Physics, Academy of Sciences of the Belorussian SSR, Minsk. Scientific-Research Institute of Organic Intermediates and Dyestuffs, Moscow. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, No. 1, pp. 105–108, January–February, 1991. Original article submitted February 24, 1989.