Efficiency of the structure analysis of complex molecules in the gas phase by their optical rotation

It was shown in the dipole approximation of optical rotation that in the general case only in orientationally anisotropic vapors is the rotational force dependent on the intramolecular orientation of both the electric and magnetic dipole moments. Expressions relating the optical rotational force to the intramolecular orientation of these moments, the orientational distribution in an anisotropic ensemble, and the configuration of a measurement have been obtained. Calculated dependences of the rotational force on the intramolecular orientation of the magnetic moment at a fixed electric moment and “rotational force excitation spectra” obtained for different types of rigid asymmetric top molecules and rotational contours are presented. It is proposed to measure the intramolecular orientation of the electric and magnetic dipole moments with the use of the rotational force normalized to that detected in the case of observation at a “magic” angle to the direction of the exciting light electric vector. Institute of Molecular and Atomic Physics of the Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 6, pp. 843–849, November–December, 1998.     

Analytical efficiency of the molecular rotational quantum echo

The sensitivity of the delay time of the molecular rotational quantum echo to change in the rotational constants of molecules was investigated with a model of the rotational quantum echo considered as an optically induced quantum synchronization of the Fourier rotational modes of an asymmetric molecular top. The J-echo and the K-echo were investigated for the A- and C-configurations of rotation of a top molecule. The contour maps of the dependence of the sensitivity of the delay time of these types of echo to changes in the rotational constants on the parameters of the molecular tops have been obtained for all the rotational constants. They show that the delay time of the rotational quantum echo is greatly dependent on the configuration of rotation of the top molecule and on the rotational constants. It is shown that the optical probing of the rotational quantum echo can also be performed by the optical rotation of the investigated molecule, and in this case the rotational force is dependent on the intramolecular orientation of the magnetic dipole moment. It was determined that a high sensitivity of the delay time of the echo to changes in the rotational constants can be responsible for the broadening of the echo pulse and even for its disappearance. Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, 70 F. Skorina Ave., Minsk, 220072, Belarus; e-mail: lssm@imaph.bas-net.by. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 6, pp. 758–764, November–December, 1999.     

Influence of spectral-dynamic effects in a laser and light guide on the dynamics of recirculation in a closed contour

The influence of stimulated emission delay, dynamic shift in generation frequency, residual charge effect, timing jitter of the radiation and excitation regime of an injection laser, as well as of dispersion in a fiber light guide on the data-internal storage time in an electrooptical contour is investigated. It is found that the storage duration of an interval depends strongly on the lifetime of nonequilibrium charge carriers, the simultaneous effect of a residual charge and jitter in an injection laser, as well as on the dc bias current of the laser. Belarusian State University, 4. F. Skorina Ave., Minsk, 220050, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 1, pp. 56–61, January–February, 1998.     

A method for resolving individual bands in absorption spectra

A new algorithm for resolving individual bands in absorption spectra is developed. It is assumed that the spectrum consists of absorption bands with halfwidths determined by different kinds of interactions—specific and nonspecific. The method has good accuracy in the case of the strong overlap of bands (the ratio of the distance between maxima of the peaks to the halfwidth is less than 0.2) and a high computational efficiency. Arkhangelsk State Technical University, 17, Naberezhnaya Severnoi Dviny, Arkhangelsk, 163007, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 3, pp. 400–404, May–June, 1997.     

The nature of empirical constants in the equation relating the frequency of the stretching vibration of oh-groups to parameters of the [MO n ]-polyhedrons coordinating these groups

Institute of Physicoorganic Chemistry, Academy of Sciences of Belarus, 220603, Minsk, Ul. Surganova, 13, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 1, pp. 104–107, January–February, 1995.     

Influence of nonplanar distortions of the tetrapyrrole macroring on the electronic states of porphyrin dications

Quantum-chemical calculations of the excited electronic states of a porphyrin dication have been performed by the CNDO/S method for different angles determining the saddle-like and ruffled distortions of the porphyrin macroring. It is shown that saddle-like distortions arising as a result of a tilt of the pyrrole rings have a significant influence on the energies of the molecular orbitals and energies of the excited electronic states of porphyrin molecules, especially on the oscillator strength of the G→Q transition. The results of the calculations performed are in good agreement with the experimental spectra of porphyrin dications. To whom correspondence should be addressed. Reported at the VIIIth International Conference on Spectroscopy of Porphyrins and Their Analogs, Minsk, September 22–26, 1998. Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 4, pp. 559–562, July–August, 1999.     

Spectroscopic study of the interaction between porphyrin and chlorin molecules of opposite charge in solutions

Institute of Molecular and Atomic Physics, Academy of Sciences of Belarus, Minsk, 220072, 70, F. Skorina Ave., Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 2, pp. 152–163, March–April, 1995.     

Special features of the use of wedge-shaped plates in a two-channel polarimeter

B. I. Stepanov Institute of Physics, Academy of Sciences of Belarus, 70 F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 6, pp. 170–173, November–December, 1995.     

Optoacoustic determination of low concentrations of gases by the use of commercial CO2-lasers

Institute of Molecular and Atomic Physics, Academy of Sciences of Belarus, 70 F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Specktroskopii, Vol. 62, No. 6, pp. 81–86, November–December, 1995.     

Temperature dependence of the width of spectral holes: Octaethylporphin in polymer matrices

Institute of Molecular and Atomic Physics, Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 2, pp. 145–150, March–April, 1995.     

Effect of sweeping the “instantaneous” lasing frequency on the amplitude-detuning characteristic of a CO2 laser with loss modulation

The influence of changes in the refractive indices of the active medium and the loss modulator on the amplitude-detuning characteristic of a CO₂ laser was theoretically investigated. It is shown that at a comparatively great magnitude of sweeping the “instantaneous” lasing frequency, the magnitude of the laser response increases not only in negative detunings, but also over a wide range of positive detunings. The use of the procedure of changing the magnitude and sign of detuning as well as the range of sweeping and the frequency of modulation makes it possible to realize various periodic and chaotic regimes of lasing, i.e., to exercise control over the time and energy parameters of pulses over a very wide range. B. I. Stepanov Institute of Physics of the Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 3, pp. 318–324, May–June, 1997.     

Relationship between the diffusion rate constant and rate constant of triplet-triplet annihilation for porphyrins in liquid solutions

Institute of Molecular and Atomic Physics, Academy of Sciences of Belarus, 70. F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 63, No. 4, pp. 613–621, July–August, 1996.     

Photophysical and photochemical properties of inclusion complexes of β-cyclodextrin with aminocoumarins

B. I. Stepanov Institute of Physics, Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 2, pp. 200–205, March–April, 1995.     

Resonance raman spectra of π-anions of Zn-porphyrins

Institute of Molecular and Atomic Physics Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 2, pp. 128–136, March–April, 1995.     

Remote spectrophotometry as applied to determination of the degree of mineralization of peat soils in polesie

Regression relations between the first main component, slope of the SBC curve towards the wavelength axis, and the degree of mineralization of peat soils are established from experimental data. Errors in determination of peat soil productivity are estimated using different spectral indices. For practical use it is recommended to measure the spectral brightness coefficients of peat soils in the 0.50–0.75 μm range. B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 1, pp. 102–106, January–February, 1998.     

Vibrational states of metal complexes of protoporphyrin IX

Institute of Molecular and Atomic Physics, Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 2, pp. 137–144, March–April, 1995.     

Picosecond dynamics of intramolecular charge transfer in benzophenone amino derivatives

Institute of Molecular and Atomic Physics, Academy of Sciences of Belarus, 70 F. Skaryna Ave, Minsk 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 3, pp. 49–55, May–June, 1995.     

Production of SO 3 − ion-radicals in barium dithionate exposed to ionizing radiation

Institute of Physicoorganic Chemistry, Academy of Sciences of Belarus, 13, Surganov Str., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 63, No. 2, pp. 258–263, March–April, 1996.     

Dynamics of a waveguide pulsed-periodic CO2 laser with loss modulation

The nonlinear dynamics of a waveguide CO₂ laser with combined periodic loss and pumping modulation is investigated theoretically and experimentally. The possibilities of controlling time and energy parameters of the output radiation using the corresponding selection of the detuning of the cavity's longitudinal mode from the center of the amplification line, the amplitude, and the frequency of loss modulation are demonstrated. The observed asymmetric dependence of the lasing-radiation density on the detuning of the cavity frequency is explained by the attendant modulation of the refractive index of the loss modulator. To whom correspondence should be addressed. B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, 68, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 4, pp. 471–478, July–August, 1999.     

Spectral methods for estimating the state of winter RYE sowings

We present the results of comprehensive investigations that include remote spectral measurements under field conditions, laboratory experiments, and mathematical simulation of the radiative regime of winter rye sowings. B. I. Stepanov Institute of Physics, Academy of Sciences of Belarus, 68, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 5, pp. 646–650, September–October, 1997.