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.     

Amplitude-detuning characteristic of a CO2 laser with simultaneous modulation of two parameters

Analytical expressions have been obtained in a linear approximation for the amplitude-detuning characteristic of a CO₂ laser with simultaneous modulation of two its parameters. It is shown that the value and form of the laser response can be controlled over a wide range by way of changing the modulation frequency, the value of the detuning, and the phase difference of the oscillations of the simultaneously modulated parameters. 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. 2, pp. 190–196, March–April, 1997.     

Nonlinear amplitude-tuning characteristic of a CO2 laser with pump-current modulation

The nonlinear amplitude-tuning characteristic of a CO₂ laser with discharge-current modulation was investigated by mean of numerical simulation. It is shown that in the general case the magnitude and shape of the laser response depend on the ratio between the frequency of the pump modulation and the fundamental resonance frequency of the laser. 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. 5, pp. 640–644, September–October, 1999.     

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.     

Amplitude-detuning characteristic of a CO2 laser with biharmonic loss modulation

The nonlinear response of a CO₂ laser to biharmonic loss modulation was theoretically investigated for tuning of the radiation frequency within the limits of the amplification band. It is shown that the value and form of the amplitude-detuning characteristic (and, consequently, the temporal and energy parameters of the laser radiation) can be controlled within sufficiently wide limits by changing the modulation frequency and the phase shift of oscillations. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 1, pp. 43–47, January–February, 1999.     

Nonlinear dynamics of the dual-wavelength CO2 laser

Theoretical studies have been made of the nonlinear-dynamic modes of operation of a dual-wavelength CO₂ laser with continuous pumping by electric discharge and loss modulation in one of the lasing channels. It is shown that by varying the modulation depth and frequency, it is possible to control, over a fairly wide range, the time and energy parameters of lasing in both channels, going from regular to chaotic modes of operation. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 3, pp. 316–321, May–June, 2000.     

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.     

Investigation of the intramembrane distribution of chlorin e6 derivatives by using fluorescence quenching

Belarusian State University, 4, F. Skorina Ave., Minsk, 220050, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 2, pp. 179–187, March–April, 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.     

Spectra of the action of photoinduced NH(ND)-rearrangement of cyanosubstituted isobacteriochlorin

Based on the measured spectra of the action of the process of cis-trans-NH(ND)-isomerization of 5-cyano-2,2,8,8,12,13,17, 18-octamethylisobacteriochlorin (H₂-COMiBCh) and its deuteroderivative (D₂-COMiBCh) in polycrystalline matrices of n-octane and r hexale at 4.2 K, it is established that the character of embedding of COMiBCh in the matrices of n-alkanes has a substantial effect on the barrier of dark rearrangement and the rate of photoinduced NH(ND)-rearrangement, while deuteration of the center of a molecule shifts the dynamic equilibrium toward a trans-form in photoexcitation. 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. 555–559, July–August, 1999     

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.     

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.     

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.     

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.     

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.     

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.     

Studies of spectral and coloristic properties of ultradispersive hematite particles

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. 157–165, November–December, 1995.