MEETINGS AND CONFERENCES

9th MEETING ON SPECTROSCOPY

(Molecular Spectroscopy Section)

On July 5–11, 1954, the 9th Meeting on Spectroscopy was held in the city of Tartu (Estonian SSR). A large number of spectroscopists took part in the meeting—physicists and chemists, industrial workers applying methods of spectral analysis, as well as representatives of related fields of science. About 750 people took part in the work of the meeting, representing various republics and cities of the Union.

In all, 184 papers were presented at the meeting. The work of the meeting proceeded mainly in three sections: 1) molecular spectroscopy, 2) general and atomic spectroscopy, and 3) spectral analysis. Questions of methods and apparatus, in particular apparatus for research in molecular spectroscopy, were considered in the second section. Several papers of the most general interest were presented at plenary sessions.

The work of the molecular spectroscopy section, in which about 200 delegates participated, showed that in the time elapsed since the preceding meeting this field had expanded substantially. More than 50 papers were presented at the 10 sessions of the section. Especially characteristic were the appearance of work on radio spectroscopy, the increase in the number of papers on infrared spectroscopy, and the broad introduction into the practice of spectroscopic investigations of objective photoelectric methods of recording spectra.

At the opening of the meeting, a large report was presented by the rector of Tartu State University, F. D. Klement, “The State of the Question of the Spectroscopy of Solid Solutions.” The speaker raised the question of the emergence in spectroscopy of a new branch—the spectroscopy of solid solutions. After a brief review of the theory of the question, the report, on the basis of literature materials and data obtained in the author’s laboratories, systematically examined the absorption and luminescence spectra of solid solutions, which include, in particular, activated crystalline phosphors. In particular, the influence of the solvent on the spectra of dissolved particles, the influence of polymorphic transitions and other factors on the spectra of solutions, as well as concentration and temperature effects, were considered. The speaker emphasized the importance of studying the spectra of solutions for theoretical spectroscopy (the influence of symmetry fields on the spectra of atoms and ions). Much attention in the report was devoted to the methodological significance of the spectroscopy of solid solutions for crystal chemistry, physicochemical analysis, and studies of diffusion in solids.

Radio spectroscopy, presented for the first time at a meeting on spectroscopy, was the subject of several reports that aroused particular interest among the participants. At the plenary session a major survey report was delivered by M. A. El’yashevich, “The present state of radio spectroscopy.” The speaker briefly characterized the specific methods of radio spectroscopy and the range of questions encompassed by these methods: the study of the fine and hyperfine structure of atomic spectra, the study of rotational levels and certain specific splittings of molecular energy levels, as well as the study of transitions between neighboring energy levels in an external electric or magnetic field. The dominant role of the region of radio frequencies of induced emission, which in the optical region is negligibly small in comparison with spontaneous emission, was especially noted. The possibilities and prospects of scientific and technical applications of radio spectroscopy were considered, in particular the possibilities of its analytical applications.

In the report by N. A. Il’yusova a survey was given of work in radio spectroscopy carried out under the direction of A. M. Prokhorov by a group of scientific workers of the Oscillations Laboratory of the Physical Institute of the Academy of Sciences of the USSR. The sensitivity of the spectroscopes with Stark modulation constructed in the laboratory reaches \(2 \cdot 10^{-8}\ \mathrm{cm}^{-1}\), with a response time of the measuring device of about 0.5 sec. The frequencies of absorption lines are thereby determined with an accuracy down to \(10^{-6}\); the error in measuring the absolute values of the absorption coefficient by the method developed in the laboratory is 5–10%. As an example of the work being conducted in the laboratory on the determination of the moments and structures of organic molecules, studies of the hyperfine structure of the line of the rotational transition \(0 \to 1\) in the molecules \(\mathrm{C}^{12}\mathrm{H}_3\mathrm{J}^{127}\) and \(\mathrm{C}^{13}\mathrm{H}_3\mathrm{J}^{127}\) were reported.

G. G. Neuimin related the experiments, carried out jointly with O. I. Chernyshëvskii, on the detection of the opto-acoustic effect in the microwave region. The aim of the work was to determine the lifetime of excited rotational states of inversion splitting by means of a method analogous to that developed by M. L. Veingerov and P. V. Slobodskaya for the optical region of the spectrum. As a result of the work it was found that for the \(\mathrm{NH}_3\) molecule these lifetimes are considerably less than \(10^{-5}\) sec., which is in agreement with the estimate made from the width of the inversion-splitting line.

A large group of reports was devoted to investigations of vibrational spectra. In their content, a substantial part of the reports was naturally connected with problems of molecular physics, chemistry, and chemical analysis. These included experimental investigations and theoretical calculations of vibrational spectra, the application of spectroscopy to the study of intermolecular interactions and chemical reactions, and the development of spectral methods of investigation and analytical techniques for the petroleum industry, plastics production, and so forth. An interesting group of works was also reported on the study of the mechanism of combination scattering of light: investigations of resonance combination scattering, the temperature dependence of line intensities, and others.

The first several reports of this group were devoted to investigations of the spectra of individual organic substances, above all hydrocarbons.

In the report by G. S. Landsberg, A. N. Shatenshtein, G. V. Peregudov, E. A. Izrailevich, and L. A. Novikov, results were communicated of investigations, by the methods of combination scattering and infrared absorption, of the vibrational spectra of diphenyl and decadeuterodiphenyl synthesized by the authors. The preparations synthesized by the method developed by the authors contained not less than 95% decadeuterodiphenyl. A careful analysis of the spectra obtained in the work

(for each substance about 60 bands were measured) made it possible to identify the fundamental frequencies, on the basis of which the authors proposed an interpretation of the spectra.

The report by V. T. Aleksanyan, B. A. Kazanskii, M. Yu. Lukin, and Kh. E. Sterin contained the results of studies of the intensities and polarization of lines in the combination-scattering spectra of a number of cis- and trans-disubstituted cyclobutanes, many of which had been synthesized for the first time. The authors established differences in the spectra of the cis and trans forms of the compounds studied and found frequencies characteristic of each form.

M. A. Kovner reported the results of calculating the vibrational spectra of a number of aromatic compounds. The author calculated the spectra of toluene and ethylbenzene and identified frequencies sensitive to the characteristics of the substituent of the aliphatic radical. The spectra of paracresol, mesitylene, and durene were also calculated. As a result of calculations of the spectrum of diphenyl, it was shown that in this molecule too the basic force characteristics of the benzene rings are retained.

A group of reports was devoted to the study of the spectra of heterocyclic compounds and of boron and silicon compounds.

L. M. Sverdlov and I. N. Zaitseva carried out a theoretical study of the vibrational spectra of diborane, $\mathrm{B_2H_6}$, for three isotopic molecules of which the authors calculated the normal-vibration frequencies on the basis of an ethylene-like model. The good agreement of the calculated frequency values with the observed ones testifies to the correctness of the model adopted. The study of the influence coefficients showed, moreover, that the internal B—H bond is half as strong as the external one.

In the work of Yu. P. Egorov, the combination-scattering and infrared-absorption spectra of a number of alkylsilanes were investigated. It was shown that in silanes, in contrast to the branched methanes also studied in the author’s work, shielding alkyl groups do not interact. On the basis of the associated simplifications of the spectrum, a new interpretation was given of frequencies in the region of CH vibrations around $2800$—$3000\ \mathrm{cm}^{-1}$.

S. G. Bogomolov, Yu. N. Sheinker, and N. Ya. Postovskii, on the basis of an analysis of infrared absorption spectra, clarified the structure of the measured sulfamic acids formed in the sulfation of 2-amino-4-methylthiazine. The question of the connection between the vibrational spectra and the basicity of cyclic amines was investigated in the work of Yu. N. Sheinker and E. M. Peresleni. The authors showed that the transition from unstrained six-membered rings to strained three- and four-membered rings is accompanied by a substantial decrease in the frequencies of the N—H bonds and an increase in the C—H frequencies. At the same time, the basicity of the compounds studied decreases in parallel, which is confirmed by the corresponding change in the force constants. The parallelism established is not, however, strict.

A number of reports demonstrated the fruitfulness of applying studies of vibrational spectra to solving analytical problems, to the study of chemical reactions, and to investigations of the physicochemical structure of matter.

In the report by V. T. Aleksanyan, B. A. Kazanskii, G. S. Landsberg, A. L. Liberman, A. F. Platé, Kh. E. Sterin, and S. A. Ukholina, the results were presented of a large study using combination-scattering spectra to analyze the aromatic portion of various lignin fractions. This study is a natural continuation of work on the methodology of gasoline analysis previously developed by the authors. In the first fractions, an analysis was made for individual aromatic hydrocarbons. The results obtained proved to be in good agreement with the group analysis of the same fractions for various

types of substitution in the benzene ring, carried out according to a procedure developed by the authors. The group-analysis procedure thus verified was applied to the higher fractions of ligroins. In these fractions there were, in addition, quantitatively determined some individual hydrocarbons, in particular diphenyls.

In the work of A. V. Iogansen, K. I. Zimina, and A. G. Siryuk, devoted to the analysis of petroleum products by means of infrared absorption spectra, information was obtained on the structural elements—aliphatic and aromatic—contained in various petroleum fractions, and certain details were elucidated concerning the composition of these fractions as a function of the method of their preparation and treatment. A. V. Iogansen also reported on the study of the infrared spectrum of the vinyl group \((\mathrm{CH}=\mathrm{CH}_2)\) and on a procedure for its quantitative determination. Having established the constancy of the integral intensities of the characteristic bands of this group, the author developed a method that makes it possible, without the use of standards, to analyze complex hydrocarbon mixtures for the content of vinyl groups in them.

The work of Yu. N. Sheinker and S. G. Bogomolov was devoted to an investigation, by means of infrared spectra, of the ambident reactivity of heterocyclic compounds, which, as the authors showed, is usually not associated with the presence of two tautomeric forms, but is due to the possibility of transfer of the reaction center along a chain of conjugated bonds, although in individual cases tautomeric forms do exist. A report devoted to the analysis of the condensation reaction of the β-ionone with ethyl ester of γ-bromocrotonic acid was delivered by G. I. Samokhvalov, N. A. Slovokhotova, M. A. Miropolskaya, L. B. Zhukova, L. A. Vakulova, and N. A. Preobrazhensky. The changes observed in the isolated reaction products in the C—O and C—C bands of infrared spectra, as well as the shifts of the corresponding bands of ultraviolet absorption, are attributed by the authors to differences in the length of the chain of conjugated C—C and C—O bonds.

The method of infrared absorption spectra was applied by A. P. Sheinker and S. S. Medvedev to the study of the structure of butadiene polymers. The authors succeeded in showing that the influence of polymerization temperature on the properties of the polymer cannot be explained by changes in its content of cis and trans configurations, as had been assumed by some investigators. V. N. Nikitin and E. I. Pokrovsky reported the results of determining, by the same method, the degree of crystallinity of polyethylene. The authors investigated the melting interval of polyethylene and studied changes in the crystallinity of this material upon stretching.

Much attention was given to reports relating to studies of the physical phenomena occurring in combinational scattering of light.

P. P. Shorygin and L. Z. Osityanskaya showed, using organic compounds with double and triple bonds as examples, that the intensity of the lines of combinational scattering increases with increasing frequency of the incident light more rapidly than follows from classical theory. The authors explain this circumstance by the proximity of the electronic absorption bands, calculate their position, and assess the relative role of the factors determining the high intensity of the lines of combinational scattering in compounds with conjugated double bonds. Related questions were considered in their report by L. M. Kutsyna and P. P. Shorygin. The authors investigated the spectra of combinational scattering of aromatic compounds upon excitation in the region of the absorption band. In this work, which is a continuation of the work of P. P. Shorygin on resonance combinational scattering, it was possible for the first time to investigate the spectra of aromatic nitro compounds. The authors also considered the conditions under which—

... excitation in their own absorption band may lead to the appearance of combination-scattering spectra. The same question was subjected to theoretical study in the work of L. N. Ovander. Considering the molecule as a set of harmonic oscillators, the author established a proportionality between the intensity of the lines of resonant combination scattering and the magnitude of the absorption coefficient in the excitation region. The phenomena of “quenching” of resonant scattering were also considered.

The report by M. D. Zege was also devoted to a theoretical study of the connection between spectra of combination scattering and electronic spectra of molecules. The author established the limits of applicability of the Volkenstein–Eliashevich formula for the intensity of lines of combination scattering and considered the conditions for the transition of combination scattering into resonant fluorescence.

Ya. S. Bobovich considered in his report peculiar anomalies in the temperature and concentration dependence of the intensity of combination-scattering lines, which he studied in detail on a large number of objects by means of an original photoelectric method he had developed. Analyzing the data obtained, the author came to the conclusion that the cause of the observed phenomena lies in the deformation of the potential curves of the excited electronic state. Taking into account the real shape of the upper and lower potential curves is essential for calculating the matrix element of polarizability.

The anisotropy of polarizability and the form of molecules of certain aromatic hydrocarbons were investigated in the work of M. F. Vuks and I. A. Bogdanov. The authors succeeded in determining the values of optical anisotropy for a number of aromatic compounds with two benzene rings and, on the basis of these data, established the mutual arrangement of the rings.

One of the sessions of the Section was devoted entirely to spectral studies of the hydrogen bond. V. M. Chulanovskii and Kim-Den-Dok showed, on the basis of consideration of the infrared absorption spectra they obtained for mixtures of acetone and methyl alcohol, that the hydrogen bond of the type OH...OCR₂ is weaker than the OH...OH bond and apparently has a different nature. In the report by V. V. Perekalina, the electronic absorption spectra of azo dyes were considered as a function of the presence in these compounds of intramolecular hydrogen bonds. From the displacement of the spectra the author established a strong perturbing action of the hydrogen-bond cycle on the alignment of bonds in the aromatic nucleus. D. N. Shigorin, examining infrared as well as electronic spectra of a number of substituted anthraquinones in vapors and in the condensed phase, also established the influence of the intramolecular hydrogen bond on the conjugation of π-electron bonds. On the basis of the differences he found in the form, position, and intensity of the infrared absorption bands associated with intra- and intermolecular hydrogen bonds, the author, noting the greater dipolarity of the latter, draws conclusions about their nature. The final propositions of the report gave rise to lively discussion and criticism. Infrared spectra were also used by E. N. Vasenko to study the association of water, formamide, and diethylformamide in solutions. By the method of quantitative measurements, V. I. Kasatochkin, M. F. Shostakovskii, O. I. Zilberbrand, and D. A. Kochin investigated association equilibria in solutions of silanols due to hydrogen bonds and their dependence on the nature of the substituent radicals.

Another large group of reports, presented at the sessions of the Section, was devoted to electronic absorption and emission spectra of molecules. In the reported works, both general questions of the theory of electronic spectra of complex molecules and particular problems connected with the study of...

molecular spectra. A number of papers demonstrated the fruitfulness of spectral methods for the investigation of various physicochemical processes and for solving analytical problems.

The papers concerning questions of the theory of the electronic spectra of complex molecules aroused great interest among the participants of the conference. This interest is quite natural, since in the theory of these spectra there are still many unresolved questions.

M. G. Veselov and T. N. Rekasheva, in their work, considered a complicated “metallic” model of complex molecules with conjugated bonds, which makes it possible to describe a number of optical properties of molecules of aromatic compounds. The complications introduced consist in taking account of internal barriers and in taking account of the displacement of electrons under the influence of substituents. The calculations performed by the authors of transition frequencies, oscillator strengths, and dipole moments for a number of complex organic molecules are in good agreement with experiment.

In a large paper by S. I. Pekar, a survey was given of the author’s works on the theory of the shape and temperature dependence of impurity absorption bands of light and luminescence in solid and liquid dielectrics. The theory is sufficiently general and covers a broad range of objects. The band shape and half-width predicted by the theory, their temperature dependence, the relation of the half-width to the Stokes shift, oscillator strengths, the relation between the energy of the optical transition and the energy of thermal activation of the corresponding thermal transitions, etc., are, as the speaker showed, in good quantitative agreement with the numerous experimental data. The paper by M. D. Borisov and A. S. Davydov was devoted to the theory of the luminescence of molecular crystals containing impurity molecules, and to a comparison of the theory with the results of the authors’ study of the luminescence of naphthalene crystals containing anthracene. Fundamental to the theory is the assumption that the excitation of an impurity molecule is of exciton character. The concentration dependence of the absolute quantum yield of luminescence that follows from the theory is confirmed by experiment and makes it possible to determine a number of important characteristics of the crystal. In the paper by M. F. Deigen, the speaker’s developed theory of the optical properties of complex color centers in ionic crystals was set forth—\(F_2\)-centers (two neighboring \(F\)-centers, considered as a single quantum-mechanical system) and \(F_2^+\)-centers (two positively charged vacancies and an electron localized near them). In the second part of the paper, the author extended the concepts of color centers in solids to liquid ionic dielectrics containing metallic impurities—to metal-ammonia solutions. This enabled the author to explain a number of optical, as well as certain electrical and paramagnetic, properties of these solutions. The possibility of extending the theory developed for solids to solutions was, however, called into question in a number of contributions during the discussion. In the paper by A. F. Lubchenko, an attempt was made to generalize the quantum electrodynamics of the vacuum to anisotropic media with the aim of developing the theory of absorption and luminescence spectra of solutions.

A number of experimental works were devoted to the relation between the electronic spectra of molecules and their structure and the physicochemical phenomena in the systems studied.

In the paper by B. S. Neporenta, V. P. Klochkov, O. A. Motovilova, and N. A. Borisevich, the results of a study of changes in the spectra of phthalimide derivatives during the gradual transition from vapors to solutions through the critical state were reported. The authors traced the gradual shift of the spectra as the concentration of the foreign substance—the solvent—increased, and came

to the conclusion that the action of the latter is due to dispersion forces and consists in shifting the electronic levels of the molecules studied. The high effectiveness of the interactions considered is noted.

Of great interest was the report by E. V. Shpol’skii and L. A. Klimova on the fine structure of the luminescence spectra of certain aromatic hydrocarbons (coronene, pyrene, 3,4-benzpyrene) in frozen solutions at the temperature of liquid nitrogen (70°K). It was shown that when the solvents are normal paraffin hydrocarbons (from hexane to nonane), the bands in the luminescence spectrum, which in other solvents have widths of the order of 100 cm\(^{-1}\), split into fine lines not exceeding, in width, the lines of an atomic spectrum. The distribution of intensity and the frequency difference in the doublets and triplets thus obtained are entirely determined by the solvent. Thus, for example, in the case of coronene in a viscous solvent (paraffin oil), at room temperature and at 70°K, comparatively narrow bands of width \(\sim 60\) cm\(^{-1}\) are observed. However, when the solvent is one of the normal paraffin hydrocarbons, each of these bands splits into fine lines (of width up to 5 cm\(^{-1}\)), forming doublets or triplets with frequency differences constant for the given solvent. On passing from one solvent to another, the emission spectrum undergoes substantial changes. One of them consists in the fact that, as the mass of the solvent molecule increases, the short-wave component of the doublet in the fluorescence spectrum remains in place, while the long-wave component approaches it, so that \(\Delta \nu\) in going from hexane to nonane decreases from 86 to 42 cm\(^{-1}\). An analogous picture also occurs in the emission spectra of the other aromatic hydrocarbons investigated. This interesting effect was interpreted in the report as the appearance, alongside the unchanged line of the emitting molecule, of a satellite with a frequency modulated by the slow (Gross) vibrations of the solvent lattice.

A. N. Nikitina and G. S. Ter-Sarkisyan reported the results of a study of the absorption spectra of nitrogen-containing heterocyclic compounds (pyridine, quinoline, acridine and their derivatives) at the temperature of liquid nitrogen and liquid hydrogen. A comparison of the spectra of various compounds shows that replacement of a methine group by nitrogen in two-, three-, and four-membered molecules almost does not change the electronic configuration of the molecules. The electronic absorption spectra were also used by V. E. Zuev to investigate the intermolecular interaction in the quinone—phenol system, leading to the formation of a complex compound—phenoquinone. From the temperature dependence of the degree of dissociation, studied by the spectral method, the author determined the dissociation energy of phenoquinone.

A. T. Vartanyan reported the results of a study of the absorption spectra of the leuco forms of thiazine and oxazine dyes in the solid state. The preceding study obtained them by reduction of solid dye films. The subsequent oxidation of the leuco forms by molecular oxygen regenerates the dyes, and in the early stages of regeneration the spectrum of the dye formed corresponds to the spectrum of dilute solutions and then shifts in the same way as occurs when the concentration of the solution is increased, which makes it possible to follow the course of aggregation of the molecules.

L. A. Klimovskaya, V. I. Vishnevskii and V. E. Shmaevskii reported on their investigation of the chemiluminescence of triaminophthalic hydrazide, oxidized by hydrogen peroxide and potassium ferricyanide in an alkaline medium, as a function of the concentrations of the solution components.

The investigation of the optical activity of solutions and vapors of compounds having rotational isomers was the subject of the report by N. M. Bazhenov and M. V. Vol’kenshtein. The authors developed an original spectrographic method of polarimetry in the ultraviolet region of the spectrum. Application of this method enabled the authors to obtain a number of interesting data on the energy difference of rotational isomers, on the influence of intermolecular interactions on internal rotation in molecules, on the dependence of specific rotation on features of molecular structure, etc.

Several reports were devoted to experimental investigations of the spectral properties of crystals. These reports dealt with studies of the positions of energy levels in a solid, the anisotropy of electronic and vibrational transitions in crystals, and also photochemical processes in a solid. Some of these questions were also considered in the theoretical reports mentioned above; nevertheless, the number of works in the field of crystal spectroscopy is still insufficient, if one takes into account the variety of problems in solid-state physics that can be studied by these methods.

In the work of A. F. Malysheva, the absorption and emission spectra of sublimate phosphors based on cadmium halide salts activated with lead were studied. In contrast to other salts, in Pb-activated CdJ₂ a new narrow absorption band arises with a maximum near 390 mμ. The author relates the difference in the behavior of the various salts to the unequal conditions of incorporation of the activator. The considerable width of the emission spectra enabled the author to express certain suppositions concerning the character of the potential curves of the excited and ground states. Ch. B. Lushchik, in his report, considered the spectra of electron levels of capture in 15 alkali-halide crystal phosphors, studied by the author with the aid of the method of thermal bleaching. The speaker showed that in the overwhelming majority of cases the capture centers are thermal microdefects of the crystal lattice of the host substance and only in individual cases are connected with the introduction of the activator into the phosphors. The thermal activation energies of the centers vary in homologous series parallel to the melting point of the host substance.

In the work of P. P. Feofilov, the anisotropy of the radiation of color centers in ionic crystals was investigated. Analyzing the characteristic dependences of the polarization of the luminescence of color centers on the relative position of the electric vector of the exciting light and the crystallographic axes of the observed crystal, he showed that in CaF₂ crystals the color centers are oriented along three axes of fourth-order symmetry, while in LiF and NaF crystals they are oriented along six axes of second order. The character of the orientation and the high degree of anisotropy of the centers enabled the author to suggest that, in the cases studied, the color centers are the so-called F₂ centers, i.e., pairs of electrons localized in neighboring vacant anion sites.

G. A. Zaitsev and B. S. Neporent reported the results of investigations of the anisotropy of infrared absorption of gypsum crystals. The authors created a microspectroscopic apparatus with a polarizer for the infrared region of the spectrum. The spectra of a gypsum crystal were investigated both in transmitted and in reflected light, and strong dichroism and splitting of a number of absorption bands corresponding to vibrations of molecules of water of crystallization and of SO₄ groups were found. The authors showed that the character of the splitting and the preferred directions of the vibrations agree with the accepted model of the lattice of a gypsum crystal.

E. A. Nesterovskaya investigated the long-wavelength limit of bleaching in photochemically colored silver halide centers, detec-

...revealing the fine structure of absorption spectra. This boundary turned out, for chloro-bromosilver emulsions, to be located at about \(1 \mu\). The coincidence of the boundary of photochemical sensitivity with the long-wavelength boundary of the Herschel phenomenon enabled the speaker to conclude that centers revealing the fine structure play an essential role in the Herschel phenomenon.

A. I. Kitaigorodskii spoke about the possibilities offered by X-ray structural analysis of molecular crystals for studying the configuration of molecules and the deformation of valence angles in crystals.

A significant place in the work of the Section was occupied by various questions of the methodology of molecular-spectroscopic investigations and their analytical applications.

An attempt to give a generalized treatment of methods for analyzing electrolyte solutions based on the study of optical properties (absorption, luminescence, refractive index, optical activity, etc.) was made in the report by A. A. Shishlovskii. The author introduced the concept of concentration optical functions (the dependence of one or another characteristic on the concentration of the dissolved substance); the study of the order of these functions makes it possible to judge the order of the reaction in the course of which the substance being analyzed is formed. In the work of A. A. Shishlovskii and I. S. Gorbany, the anomalous dispersion of light in solutions of complex organic compounds was investigated. On the basis of the nonlinearity of the concentration function of the refractive index, the authors proposed a method for the quantitative analysis of multicomponent mixtures. The possibility of such analysis was disputed by some participants in the discussion, who pointed out that the required accuracy of measurement is difficult to attain with existing refractometric methods.

The report by P. A. Bazhulin, S. G. Rautian, A. I. Sokolovskaya, and M. M. Sushchinskii, devoted to the analysis and development of methods for studying the width of lines of combination scattering of light, was heard with interest. The authors carried out a systematic analysis of the influence of the instrumental function of the spectrograph and of the width of the exciting line on the observed contour and width of lines of combination scattering, and as a result proposed a method for determining the true contour of a line from the observed one. Measurements were also made of a number of combination-scattering lines with the aid of a spectrograph of large dispersion. The data obtained were used to refine the method for determining line widths, based on comparing the intensities at the maximum and the integral intensity.

The question of taking into account the distorting influence of the optical system of a monochromator on the contour of a spectral line was also considered in the report by I. V. Peisakhson. The author showed that if the observed contour of a spectral line can be expressed analytically, then the true contour can be calculated with the necessary accuracy.

Of great interest to the participants of the Conference was also the report by O. P. Girin, Z. V. Zhidkova, B. I. Stepanov, A. P. Ivanov, and A. S. Toporets on determining the spectrum of true absorption of scattering colored objects from the spectrum of their diffuse reflection. The authors succeeded in obtaining expressions that make it possible to calculate (in good agreement with experiment), from given experimental curves of spectral reflection and from given particle sizes and refractive indices, the spectral absorption curves of the substance of which the particles consist. In the second part of the report, attention was focused on the difference in the properties of light scattered by the surface of an object and by its internal layers (the external and internal components).

In the report by A. N. Shabadash and L. A. Igonina, a method of quantitative analysis using ultraviolet absorption spectra of vapors was presented. The authors developed an absorption cell for studying vapor absorption spectra at elevated temperatures with an SF-4 spectrophotometer or spectrograph. The possibilities of the method were illustrated by the authors with the example of the analysis of residual styrene in polystyrene and phenol in phenol-formaldehyde resins.

M. L. Sosinskii described further improvements to the low-pressure mercury lamp he is developing for the study of spectra of combinational scattering.

The work of the Section took place in an atmosphere of active discussion of the reports, which was facilitated by the participation in the discussions of representatives of many branches of science and industry. In addition to physicists-spectroscopists, physicochemists, organic chemists and analytical chemists, specialists in solid-state physics, and others also took an active part in the work of the Section. In this connection, the discussions, at times sharp, were many-sided and almost always fruitful.

The work of the Section demonstrated significant growth in research in molecular spectroscopy over the two years that had elapsed since the 8th Meeting. In some of the reports the problems posed for molecular spectroscopy were essentially solved; other reports demonstrated the fruitfulness of using the methods of molecular spectroscopy to solve a variety of problems posed by modern science and technology. At the same time, some directions of theoretical and applied molecular spectroscopy were not presented with sufficient completeness.

The Meeting showed the need to intensify the further development of fundamental questions of molecular spectroscopy and the importance of a broader introduction of the methods of molecular spectroscopy into various branches of the national economy.

B. S. Neporent, P. P. Feofilov

From the Editors

Reports on the work of the sections on general and atomic spectroscopy and spectral analysis will be published in one of the forthcoming issues of the journal.