V. B. Morozov

Broadening Peculiarities of Vibrational Bands in the Spectrum of Carbon Dioxide Close to the Critical Temperature

Carbon dioxide Fermi doublet 1388/1285 cm−1Q-band broadenings and shifts measured using coherent anti-Stokes Raman spectroscopy are presented. Measurements were performed over a wide density range (0.1ρc < ρ < 1.9ρc) during compression in the gaseous and condensed states at temperatures close to critical (the reduced temperature values were Tr = 0.995, 1.000, and 1.006). At densities above the ρc critical value, the width of Q-bands did not increase as the density grew, and the low-frequency Q band considerably narrowed up to the density value 1.7ρc. The main reason for this anomalous behavior was progressing narrowing of the spectral contribution caused by the special features of rotational exchange in the condensed state and not related directly to the closeness to the critical point. The refined critical broadening value was about 10% of the width for the high-frequency Q-band and 15% of the width for the low-frequency Q-band.

CARS diagnostics of phase transitions of molecular media confined in nanopores

Coherent anti-Stokes Raman Scattering (CARS) spectroscopy proved to be a powerful tool for diagnostics of states and phase transitions of molecular media confined in nanopores [1–3]. Contributions of gas phase, molecular layers adsorbed on the pores surface and liquid-like condensed state inside pores can be recognized using the analysis of measured CARS spectra. Phase transitions can be revealed by appearing or disappearing of corresponding contributions in measured spectra. In present investigation we apply CARS to study condensation of carbon dioxide in different nanoporous glass samples (NGS) with pores of several nanometers.

Parametric amplification of broadband radiation of a cw superluminescent diode under picosecond pumping

It is proposed to use cw superluminescent diodes with a spectral width of about 300 and high spatial coherence as seed radiation sources in parametric amplifiers with picosecond pumping in order to form broadband picosecond pulses. A two-cascade parametric amplifier based on (BBO) crystals is pumped by pulses of the second harmonic of an Nd : YAG laser. For a superluminescent diode spectral width of (centre wavelength ), the spectral width of picosecond pulses at the parametric amplifier output is . At a total pump energy of for BBO crystals, the energy of the enhanced emission of the superluminescent diode is found to be .

Quasi-rotational widely ranging spectrum generation by self-focusing of picosecond pulses in high-pressure hydrogen

A sequence of quasi-equally spaced spectral lines, ranging from the IR to the UV was obtained, when 1.06-micrometers linearly polarized pulses of duration 30 ps and energy of up to 40 mJ were focused into a cell filled with hydrogen at pressures of up to 120 atm and formed there is a self-focusing channel. The average frequency interval between spectral lines was approximately equal to the frequency of rotational transition in hydrogen 587 cm-1. These lines exhibited a substructure made up by components produced in hydrogen by stimulated rotational and vibrational Raman scattering and cascaded four-wave parametric processes. In the visible, the energy of each spectral line was around 10(mu) J.