Proceedings Volume 5067

Saratov Fall Meeting 2002: Laser Physics and Photonics, Spectroscopy, and Molecular Modeling III; Coherent Optics of Ordered and Random Media III

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Proceedings Volume 5067

Saratov Fall Meeting 2002: Laser Physics and Photonics, Spectroscopy, and Molecular Modeling III; Coherent Optics of Ordered and Random Media III

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Volume Details

Date Published: 23 September 2003
Contents: 10 Sessions, 38 Papers, 0 Presentations
Conference: Saratov Fall Meeting 2002 Laser Physics and Photonics, Spectroscopy, and Molecular Modeling III; Coherent Optics of Ordered and Random Media III 2002
Volume Number: 5067

Table of Contents

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Table of Contents

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  • Fundamental of Electromagnetic Field Propagation
  • Laser Polarimetry of Objects with Complex Structure
  • Industrial and Medical Applications of the Traditional and Novel Coherent Optical Techniques
  • Image Processing for Industrial and Biomedical Applications
  • Addendum: Selected Internet Presentation
  • Plenary Lecture
  • Laser Physics and Nonlinear Optics
  • Atoms in Laser Fields
  • Laser Interferometry and Quantum Optics
  • Spectroscopy and Molecular Modeling
Fundamental of Electromagnetic Field Propagation
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Angle dependence of chromatic polarization converstion of terahertz radiation by a density-modulated two-dimensional electron system
Vyacheslav V. Popov, Olga V. Polischuk
Results of a theoretical investigation of the angle dependence of chromatic polarization conversion of the electromagnetic wave (EW) in a density-modulated two-dimensional (2D) electron system are presented. A giant enhancement of the polarization conversion efficiency is found to emerge under plasma oscillation resonance in the periodic 2D electron system. At normal incidence, the greatest polarization conversion takes place when the angle between the plane of incidence of the EW and the direction of the periodicity of the system (azimuthal angle)is equal to 45°. At oblique incidence, the value of the azimuthal angle, at shich the maximum polarization conversion in the system occurs, deviates from 45° depending on a particular value of the contrast ratio of dielectric constants of media surrounding the 2D electron system. The greater the contrast ratio, the smaller the deviation. In the total reflection regime, the total polarization conversion can be reached, if the electron scattering in the 2D electron system vanishes. In contrast to the refringence case, the frequency of the polarization conversion resonance deviates with the angle of incidence and azimuthal angle at the total reflection regime as a result of the field confinement in the vicinity of the 2D electron system. Numerical calculations are performed for the characteristic parameters of an actual 2D electron system in the electron inversion layer on p-Si at the terahertz frequencies.
Generating Gaussian beams using energy-efficient phase DOEs
Svetlana N. Khonina, A. A. Almazov
The paper is devoted to designing energy-efficient phase DOEs to generate Gauss-Laguerre modes, ψ0m(r,φ),mM. The DOEs are designed using the Lesem method. For the DOEs operating a plane illuminating beam the optimal DOE aperture radius is calculated. For the DOEs illuminated by the Gaussian beam an extra aperture is not employed, with the radius of an optimal effective radius of the illuminating Gaussian beam calculated in this case. As distinct from the earlier works, the DOE-generated images are being scaled, which results in fairly low root-mean-square deviation and geometric error.
Analysis of the electromagnetic wave diffraction by 2D micro-optics objects using the decomposition in terms of cylindrical functions
Victor V. Kotlyar, M. A. Lichmanov
We propose a method to calculate the intensity distribution resulting from the diffraction of plane TE- or TM-waves by a dielectric homogeneous cylinder of arbitrary cross-section. With this method, the field within and outside the cylinder is decomposed into a series in terms of cylindrical functions, representing the partial solutions of the Helmholtz’s equation. The series coefficients are being found from the condition that the internal and outside fields should be conjugate on the cylindrical object interface. A method for calculating the field of a plane wave diffraction by a multi-layer dielectric cylinder of circular cross-section is also proposed. For the number of homogeneous layers greater than two the problem is reduced to solving a linear set of algebraic equations, while with only tow layers the analytical relationships for the diffraction field have been derived. The intensity distribution resulting from diffraction of the plane TE-wave by a two-layer dielectric cylinder is numerically simulated using two methods - a finite elements method and via analytical formulae.
Frequency-domain optical diffuse tomography: trajectory approach to the problem of reconstruction
Olga V. Kravtsenyuk, Alexander G. Kalintsev, Vladimir V. Lyubimov
The paper is devoted to development of the reconstruction algorithm for optical diffuse tomography using frequency-domain technique. On the base of theoretical investigations and experimental results a new method is proposed for the description of propagation through strongly scattering objects of the optical radiation generated by intensity modulated CW laser source. The method designed for developing the fast trajectory algorithm of tomographic reconstruction of an object’s internal structure with separation of absorbing and scattering parameters. The reconstruction experiment has shown that the net processing time was not over than 0,3 s for 2D image. The presented images illustrate the applicability of this algorithm for the optical diffuse tomography.
Laser Polarimetry of Objects with Complex Structure
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Polarization tomography of tissues in early diagnostics of uterine cervix
A. P. Peresunko, A. G. Ushenko, S. M. Michailov, et al.
This paper is dedicated to the analysis and experimental testing of the concept of laser polarization probing of tissues. The methods of increasing the signal-to-noise ratio in coherent images of the optically anisotropic architectonics of the morphological tissue structure are considered. The possibilities of polarization selection and contrasting of such images screened by other tissues are examined. The influence of the polarization degree of the scattered background on the signal-to-noise ratio is investigated. The possibilities of polarization correction of the probing beam for contrasting tissue images are analyzed.
Polarization-correlation study of biotissue multifractal structure
O. I. Olar, A. G. Ushenko
This paper presents the results of polarization-correlation study of multifractal collagen structure of physiologically normal and pathologically changed tissues of women’s reproductive sphere and skin. The technique of polarization selection of coherent images of biotissues with further determination of their autocorrelation functions and spectral densities is suggested. The correlation-optical criteria of early diagnostics of appearance of pathological changes in the cases of myometry (forming the germ of fibromyoma) and skin (psoriasis) are determined. This study is directed to investigate the possibilities of recognition of pathological changes of biotissue morphological structure by determining the polarization-dependent autocorrelation functions (ACF) and corresponding spectral densities of tissue coherent images.
Wavelet analysis of dynamics of changes in orientation-phase structure of biotissue architechtonics
O. Y. Wanchulyak, V. T. Bachinsky, A. G. Ushenko, et al.
This work is devoted to the elaboration of complex polarization-correlometry and wavelet-analysis of object laser fields, formed by the structured biotissues with further approbation of principles of optical diagnostics of tissue physiological state. The histological sections of physiologically normal muscular tissue of a rat heart (group A) and necrotically (infarct) changed tissue (group B) were investigated.
Polarization-correlation study of biotissues such as myoma and uterine cervix
A. P. Peresunko, A. G. Ushenko, L. A. Plavyuk, et al.
The paper presents the results of polarization-correlation investigation of multifractal collagen structure of physiologically normal and pathologically changed tissues of women’s reproductive sphere. The technique of polarization selection of coherent biotissues’ images with the following determination of their autocorrelation functions and spectral densities is suggested. The correlation-optical criteria of early diagnostics of pathological changes’ appearance of myometry (forming of the germ of fibromyoma) and of uterine cervix (precancerous) are determined. The suggested paper is directed to investigation of the possibilities of pathological changes of biotissues’ morphological structure by means of determining the polarizationally filtered autocorrelation functions (ACF) and corresponding spectral densities of their coherent images.
Polarization monitoring of structure and optical properties of the heterogeneous birefringent media: application in the study of liquid crystals and biological tissues
Dmitry A. Yakovlev, S. P. Kurchatkin, A. B. Pravdin, et al.
The original method of the polarization monitoring of heterogeneous anisotropic media is proposed. In contrast to the known approaches, the proposed method is applicable for the analysis of structure and optical properties of anisotropic media with an azimuthal variation in the local optical axis orientation with respect to the direction of probing. As a consequence, it can be used for studying the media, which contain anisotropic chiral structural fragments. The experimental examples are given, which show the possibility of applying this method in the study of liquid crystals and tissues.
Industrial and Medical Applications of the Traditional and Novel Coherent Optical Techniques
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Quasi-parallel laser-Doppler perfusion imaging using a CMOS image sensor
Alexander N. Serov, W. Steenbergen, F. F. M. de Mul, et al.
We utilized a CMOS (Complementary Metal Oxide Semiconductor) video-camera for fast flow imaging with use of the laser-Doppler technique. A single sensor is used for both observation of the area of interest and measurements of the interference signal caused by dynamic light scattering from moving particles inside scattering objects. Particularly we demonstrate the possibility to image the distribution of the moving read blood cell concentration. This is a first step towards laser Doppler imaging without scanning parts, leading to a much faster imaging procedure compared to existing mechanical laser Doppler perfusion imagers.
Creation of optical waves with the predetermined structure on the base of the spatial light modulator
Dmitry K. Proskurin, A. S. Orlov
The approach for investigating the discrete spatial light modulator (SLM) with the goal of developing the predetermined optical wave structure with the essential control of phase is suggested. Specific interest is the obtaining the wave with predetermined structure in Fresnel and Fraunhofer approaches. The estimate is performed for developing functional and statistical forms of waves. The numeric models for optical wave transforms are used.
Relative displacement determination of surfaces of two objects by means of speckle-field dynamic interference in the image plane
Alexander Petrovich Vladimirov, P. S. Eremin
The interference of two speckle-modulated waves reflected from two three-dimensional deformable objects and passed through the image-forming lens system is theoretically considered. The equation connecting a vector of relative displacement of surfaces of two objects and the change of interference order in the region of their images overlapping is obtained. In the case of the coincidence of the objects illumination and observation, the equation precisely concurs with the similar equation in holographic interferometry. For verification of the validity of this theory, the experiment, in which deformation of the membrane was studied by a new method and by a method of real time holographic interferometry, was carried out. It is demonstrated the good correlation of results obtained by both methods.
The second-order speckle mechano-optical effect: theory and experiment
Alexander Petrovich Vladimirov, E. V. Udartsev
The three-dimensional model of scattering deformable object is considered. On this basis, the expression for function of mutual spatial-temporal correlation of light intensity in free space is obtained. Some special cases allowing us to obtain analytical relations between object deformations and speckle displacements are discussed. Theoretically predicted effect of speckle displacement along the z axis is analyzed using the assumption about object deformation in xy plane. The experimental verification of this effect was carried out. The experimental setup and obtained data are discussed.
Laser wave front matching interferometer for thickness measurements
Dmitry V. Lyakin, Mikhail I. Lobachev, Vladimir P. Ryabukho
The so-called Laser Wave Front Matching Interferometer (LWFMI) is developed for thickness measurements of transparent films and layers with high spatial resolution. This interferometer is constructed under scheme of Michelson interferometer with focusing microobjectives in the interferometer arms (Linnik scheme) and wide integrating detector aperture in common exit branch. The peaks are observed in the envelope of interference LWFMI signal as function of object displacement relatively to the focal point of an interferometer focusing objective when the probing beam is focused on the front and rear surfaces of a layer. The distance between the interference peaks is proportional to the geometrical thickness of a layer and can be measured by the technique of interference fringe counting, if the refractive index of layer medium is known. The results of geometrical thickness measurements of some objects by this interferometer for high numerical aperture of probing focused beam are discussed.
Speckle correlometry visualization of imbibition front
Laser speckle correlometry was used to study interphase boundary development in paper sheet. The active imbibition area was clearly defined and observed for all samples by higher rate of speckle intensity fluctuations. In some cases wetting of paper lead to formation of rough front which static shape and dynamics of the motion shows considerable complexity. This effect comes out from randomness in porous system and existence of macroscopic obstacles that require additional pressure to be overpassed.
Spectral analysis of non-stationary speckle fluctuations: different data processing techniques
The methods of wavelet analysis and Hilbert transform are used to study the intensity fluctuations of a laser light scattered by interphase boundaries in the layer of a porous medium (paper) during evaporation of a volatile liquid with which the layer was impregnated. The analysis was performed using the Morlet wavelet as the base transformation function. The obtained spectra reflect characteristic features of the development of the evaporation front, which correspond to various stages of the process of nonstationary mass transfer in the porous layer-volatile liquid system studied.
Vibration amplitude determination from the spectrum of an autodyne signal of a semiconductor laser
Dimitry A. Mashkov, Anatoli V. Skripal, Dmitry A. Usanov
A method of amplitude determination of mechanical vibrations from the spectrum of autodyne signal of semiconductor laser is described. The relation between the vibration amplitude of an object and the frequency of spectral component with the maximal amplitude in the spectrum of the autodyne signal is obtained. The least-squares method is used to obtain the approximation coefficient. Measurements of vibration amplitude of piezoelectric plate were carried out with the help of a semiconductor laser autodyne system.
Coherent light small-angle scattering as applied to monitor the thermal denaturation of collagen tissue
Thermal modification of collagenous tissue (e.g. cartilage) used for its reshaping is a modern approach in laser medicine. The necessity to provide conditions for proper tissue modification and to avoid the dramatic changes in tissue structure due to collagen denaturation requires to provide the real-time monitoring of the process. One of the possibilities for such monitoring procedure is related to the analysis of the dynamic scattering of a probe coherent light by treated tissue. In this work we studied some peculiarities of the small-angle dynamic scattering of probe laser light by thermally treated collagenous tissues.
Image Processing for Industrial and Biomedical Applications
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Digital imaging of human skin
Leonid E. Dolotov, Irina A. Kiseleva, Yury P. Sinichkin, et al.
We report a new method for quantitative analysis of erythema and pigmentation of the human skin using of the skin surface image. The erythema and pigmentation indices as well as the polarization degree of backscattered light are applied as the visualization parameters. The comparative analysis of the quality of various types of images is performed. Quality of reconstructed images was estimated in terms of image contrast. It is shown that the skin image contrast for the case of the erythema index as visualization parameter as well as the image contrast for the case of the pigmentation index as visualization parameter exceed at least in three times the similar values for the conventional color image or R, G, B image components. Maximum value of the contrast can be achieved in the case of using the polarization degree as the visualization parameter. The reported method of skin imaging can be used as an objective tool for diagnostics of the skin diseases.
Criteria of identification of medical images
Sergey I. Suyatinov, Sergey V. Kolentev, Tatyana I. Bouldakova
Development of methods for indirect measurement of substance’s consistence and characteristics is the highly actual problem of medical diagnostics. The criteria of identification of the medical images are considered with the purpose of detection of pathological areas. It is shown that the relative density of the tissue is one of such criteria. In addition it is necessary to take into account the parameters of technical equipment used for obtaining of images.
A digital algorithm for reconstructing fringe connectivity in the interferograms of vibrating objects
Alexander G. Khramov, V. V. Kotlyar, A. A. Kovalev
We study into the ways of eliminating the interferogram fringe discontinuities and obtaining the connected interference fringes, which is needed for wave reconstruction. For this purpose, the decision function was calculated for pairs of fringe discontinuity points with regard to a variety of fringe geometric characteristics. The studies are conducted using computer-simulated interferograms. The developed algorithms are shown to be suitable for eliminating fringe discontinuities and obtaining connected interferogram fringes.
Addendum: Selected Internet Presentation
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Photorefractive holography for real-time coherence gated imaging
Christopher W. Dunsby, Y. Gu, Z. Ansari, et al.
Wide-field low coherence photorefractive holography has the potential to acquire coherence gated images at over 1000 frames/second, including through scattering media. We demonstrate photorefractive holography using a photorefractive multiple quantum well device and we demonstrate that it can be applied to real-time imaging of a moving watch cog. The use of higher frame rate of the CCD cameras will permit imaging at even greater frame.
Plenary Lecture
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IR laser welding of thin polymer films as a fabrication method for polymer MEMS
William A. Beck, Michelle Huang, Joe Ketterl, et al.
MEMS (Micro Electro-Mechanical Systems) continue to be something of a solution looking for a problem. Even as the glamour has moved on to the smaller realm of nano technologies and devices, progress continues towards making micro-scale devices more useful and manufacturable. One avenue this work is taking is into the realm of polymer MEMS, shifting from the expensive, complicated methods of semiconductor processing to the much simpler methods of plastics processing. Polymeric materials are rugged, lightweight and low cost, and their use in manufacturing has a long history. While many bulk polymer manufacturing processes such as molding, machining and adhesive bonding are adaptable to the micro realm, their use in MEMS devices often requires development of specialized processing methods. Here we report on development of laser welding as a bonding method for thin polymer films, including automation of the welding process, steps towards standardization of that process, preparation of standardized test samples, and development of specialized test methods used to evaluate the strength of polymer welds. Our initial results show a direct correlation between welding parameters and weld strengths.
Laser Physics and Nonlinear Optics
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Transient self-action of periodically modulated laser beams
Vladimir L. Derbov, V. V. Serov, I. L. Plastun, et al.
We study the self-action of an amplitude-modulated beam in a two-level saturable absorbing medium. We also consider the radial quadratic dependence of the linear refraction index to apply the results to doped waveguides. As the modulation period approaches the relaxation times, the medium response is no more instantaneous, so that one should solve the full set of Maxwell-Bloch equations. We propose a second-order scheme with the Gauss-Laguerre transformation of the transverse field pattern. A simplified approach based on the synchronous interaction approximation is used for thin layers. We analyze the transient behavior of the medium response and its manifestation in the modulation of the beam diffracting after a thin saturable absorber. Nonlinear distortions of the modulation signal passed through a doped waveguide appeared to be unexpectedly small compared with those of the local polarization and population difference.
Resonant surface polaritons of a cylindrical three-layer waveguide in far IR-range
Mikhail N. Libenson, D. S. Smirnov
We report the results of the theoretical investigations of the existence of peculiarities of the surface electromagnetic waves (SEW) in a cylindrical three-layer waveguide on the metal-dielectric boundary in far IR range where the electrodynamical characteristics of the metal are described only in the approximation of normal skin effect. We consider the problem of the field structure of SEW, its parameters of attenuation from both sides of the medium boundary, its propagation length along the cylindrical surface. The Leontovich boundary conditions were used. The problem solved has significant value for near-field optics (NFO) in the far IR range where the principles of NFO are only being established.
Loss measurement in perfect-structure glass holey fibers
Yuliya S. Skibina, L. A. Melnikov, P. Glas, et al.
The results of investigations of transmission properties and experimental measurements of losses in different kinds of holey fibers made from optical glass are presented. In the experiments the air-glass holey fibers with Nd-doped core and metal-doped core were used. Special attention was given to the quality of the holey fiber structure. The transmission properties were investigated at the wavelengths 0.633 μm and 1.05 μm (He- Ne laser and IFL laser, correspondingly). The losses at 1.05 μm are 0.00025 cm-1, being slightly smaller than the losses in bulk glass.
Gain properties of one-dimensional photonic crystals with finite number of active layers
The gain factor for the light propagating in one dimension (1D) photonic band-gap (PBG) structure having active layers with was calculated using the transfer matrix formalism. The frequency dependencies of the reflection and transmission coefficients, and threshold conditions of 1D photonic crystal with finite length are presented. The structure containing thin metal layers is considered also. Possible mechanisms of gain enhancement were discussed.
Atoms in Laser Fields
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Model of interaction of zero-duration laser pulses with an atom
Yuri V. Popov, K. A. Kouzakov, A. A. Gusev, et al.
The soluble model of interaction of a finite series of zero - duration pulses with an atom is considered. The model is based on the nowadays laser techniques providing duration of pulses of a few femtoseconds and even less, and intensities higher than 1014-1020 Wt/cm2.
Influence of the asymmetry of optical transitions in a three-level atom on the CPT-resonance
Anna V. Kuptsova
The characteristics of CPT-resonance, i.e. its width, depth and contrast, are considered for the three-level Λ-atom interacting with two resonant monochromatic radiation fields. We develop the computer simulation to investigate the influence on these characteristics of the asymmetric properties of medium: inequality of the dipole moments and inequality of the relaxation rates of population. Both weak and strong radiation fields are considered. For the weak fields the inequality of the Rabi-frequencies is found to influence weakly or even not to influence on the CPT-resonance shape. For the strong fields we found the significant influence of the asymmetry on the shape. We conclude that the CPT-resonance in the strong fields can be utilized as a tool for measure of the optical transitions asymmetry. As an example of the real system interacting with two strong radiation fields we consider the characteristics of the CPT-resonance for the magnetic sublevels of states 6P1/2, 6P3/2 and 7S1/2 for Tl-atom.
Adaptive numerical methods for the time-dependent Schrödinger equation in atomic and laser physics
Vladimir L. Derbov, M. S. Kaschiev, V. V. Serov, et al.
Stable adaptive methods for solving the time-dependent Schrodinger equation (TDSE)) are considered in the framework of conventional finite-element representation of smooth solutions over coordinate spaces of a projective type with long derivatives. Generalization of Cranck-Nicholson scheme of forth order in time step is implemented. Projective “hidden variable” representation of strongly oscillating solutions is realized to extract explicitly the strongly variable gauge phase factor and to evaluate only the “pilot solution” which is reduced to a smooth envelope of the solution under consideration. Such an approach corresponds to the known transformation from Euler space variables to Lagrangian ones and the inducing characteristic representation of self-similar solutions widely used in the flow propagation problems. We study both smooth and strongly oscillating solutions of TDSE describing conventional atomic models in the laser pulse field. It is shown that for short-range potentials the “pilot solution” can be naturally interpreted as the spectrum of the outgoing wave. The examples considered show the efficiency and stability of the elaborated methods.
Laser Interferometry and Quantum Optics
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Modulation interference microscope
P. A. Osipov
The memo in brief of a new type of optical microscopes is given. They make it possible to obtain the true geometric picture of an object with the best resolution up to 0.01λ.
Account for topological phases in interferometric measurements
V. A. Andreev, K. V. Indukaev
The structure of the phase arising when a probing light beam passes an optical system is analyzed. Its value is determined by the length of the optical path of the beam, by the geometry of the trajectory and by the optical properties of the reflecting surface. This phase is a sum of the linear phase, the Fresnel phase and the Rytov-Vladimirski phase. An interferometer measures the sum of all these separate phases. We propose a method to extract these separate phases from the total one and, therefore, determine the corresponding characteristics of the object. In the case of an isotropic object the explicit formulas are found. The device based on this approach combines the properties of both a profilometer and an ellipsometer.
The problem of sub-Rayleigh resolution in interference microscopy
Konstantin V. Indukaev, V. A. Andreev
The method allowing one to achieve sub-Rayleigh resolution in optical interferometric microscopy is offered. It is shown that for this purpose it is not necessary to overcome the diffraction limit. Generally speaking, “sub-Rayleigh resolution” and “overcoming of diffraction limit” are essentially different concepts. Our method uses the modulation of all parameters of a light source and the separation of the phase shifts of different origin. The method is worked out that makes it possible to measure the different phases separately and, therefore, to determine the related characteristics of an object. Our approach opens a way to a new type of optical devices. These devices can determine both geometrical and material parameters of the object in a unique measuring procedure.
Quantum carpets and fractals for superpositions of states of photons
Alexander V. Gorokhov, A. V. Shaikin
Examples of Berry’s and WBBZ - (D.Wojcik, I.Bialynicki-Birula and K.Zyczkowski) quantum fractal constructions are considered. The behavior of fractal dimensions of these objects is investigated in going from coordinate representation to momentum and coherent state representations. The mean value of quanta and dispersion for isolated quantum harmonic oscillator prepared in "fractal" state and interacting with another oscillator are calculated.
Spectroscopy and Molecular Modeling
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Spectroscopic parameters of high exited vibrational states of molecules
Svetlana P. Gavva
The algebraic method of disturbance theory is applied to solve the problems of molecular spectroscopy. Within the framework of this method, the formulae have been obtained determining the shifts of bands centers, the change in coefficients of excited vibrational states form, and the change in the elements of kinematic interactions matrix for the n-order of disturbance theory.
Conformational analysis of alkyl- and fluoroalkylcyclohexanecarboxylic acids by infrared spectroscopy methods
Lev M. Babkov, G. A. Puchkovskaya, E. S. Vedyaeva
Modelling of IR spectra has been carried out for alkyl- and fluoroalkylcyclohexanecarboxylic acid sets, which experimental spectra in the temperature range of 77-500 K were received earlier. This modelling took into account the conformational mobility of molecules and the hydrogen bond energy decreasing in H-complexes during heating. Temperature dependent changes of spectra have been shown to be caused by conformational transitions, accompanied with turns of the alkyl (fluoroalkyl) radical or carboxylic groups and the energy decreasing of hydrogen bond during heating.
IR spectra, molecular modeling, and structure of 4'-pentyl-4-cyanobiphenyl
Lev M. Babkov, I. I. Gnatyuk, G. A. Puchkovskaya, et al.
Conformational mobility and structure of 4' - pentyl - 4 - cyanobiphenyl in liquid and liquid-crystal states have been investigated by IR spectroscopy methods (both experimental and theory). IR absorption spectra have been measured in the 26° - 150°C temperature range, in the 400 - 4000 cm-1 spectral region. Theoretical modeling of IR spectra has been done by the method of fragments. Comparison between theoretical and experimental spectra allowed to draw a conclusion that samples under investigation were mixtures of different conformers. Spectral changes with temperature have been defined by the molecule conformational mobility which is small under the certain conditions. The most probable molecule configurations, realized in the sample in the mentioned temperature interval have been determined.
Computer simulation and experimental study of the polysaccharide-polysaccharide interaction in the bacteria Azospirillum brasilense Sp245
Oksana A. Arefeva, Pavel E. Kuznetsov, Sergey A. Tolmachev, et al.
We have studied the conformational properties and molecular dynamics of polysaccharides by using molecular modeling methods. Theoretical and experimental results of polysaccharide-polysaccharide interactions are described.