A.M. Prokhorov

Spectral characteristics of the SF6 molecules excitation by a strong IR laser field at continuously tuned radiation frequency

Abstract The frequency dependence of the energy absorbed by the lower vibration levels system in SF 6 has been investigated using a pulsed high pressure CO 2 -laser continuously tuned over frequency domain. The absorption of these molecules in the intense IR laser field has been experimentally found to have well developed contrast absorption features. Two-photon absorption players an important role in the absorption spectrum structure formation. The observed spectral structure gives evidence on the strong anharmonicity splitting of the SF 6 molecule v 3 mode degenerated states.

High resolution cw cars spectroscopy of the q-branch of the ν2 band in C2H2

The fully resolved spectrum of the Q-branch of the ν2 band in acetylene has been obtained by cw CARS spectroscopy with a resolution of 40 MHz. The dispersion of χ(3) and the linewidth of this Raman mode were investigated over the pressure range 0.05–5 atm. The constant of rotational-vibrational coupling was measured to be £ = (5.91 ± 0.05) × 10-3 cm-1.

High resolution cw CARS spectroscopy in D2 gas

Abstract The result of spectroscopic measurements of the Q-branch of gaseous D2 by the method of coherent anti-Stokes Raman scattering are presented. The experiments were carried out with cw single-frequency lasers. The resolution was 40 MHz. The dispersion of |χ(3)| was investigated and its maximum value was estimated to be (0.7 ± 0.3) × 10-13 esu at 1 atm pressure. The full width of Q(2) line versus pressure was measured over the range of 0.06–40 atm. Signal to noise ratios reached 105 in our experiments.

Laser isotope separation of rare earth elements.

The experimental results on the laser isotope separation of the neodimium, samarium, europium, gadolinium, dysprosium, and erbium by the selective two-step photoionization are given. The rare earth elements have been chosen for the investigation because they constitute a good series of the very similar but different atoms that are heavy enough and allow experiments to be carried out that are representative enough. The experimental technique developed for the laser isotope separation experiments has been applied to measure the excitation energy transfer cross sections at the collisions in the gas of the same atoms ((153)Eu ? (151)Eu, sigma = 1.4 x 10(-13) cm(2)). The combination of the selective two-step photoionization and ion mass filtration allowed us to develop a very convenient technique for the precise measurement of hyperfine structure in the spectrum of odd isotopes. The examples of dysprosium and erbium are given. The technique is good for the rare and unstable isotopes as well. The ionization cross sections for the transition starting off the excited level have been estimated ( approximately 10(-17) cm(2)). For the example of gadolinium the possibility of creating neutral atomic vapor dense enough for laser isotope separation by the electron-beam evaporation technique has been demonstrated.

A tunable infrared parametric oscillator in a CdSe crystal

Abstract We have demonstrated an infrared singly resonant parametric tunable oscillator in a CdSe crystal. The oscillator was pumped at 2.36 μ (CaF 2 : Dy 2+ laser) and has been operated with peak output power in the tens kW range. Tuning from 2.8 μ to 3.36 μ and from 7.88 μ to 13.7 with 1.5 cm − bandwidth was obtained with a good temperature stability of the parametric wavelengths.

The vaporization of a metallic target by a microsecond pulsed TE-CO2 laser radiation

Abstract The analysis of some new experimental data has proved that the evaporation of a stainless steel target in vacuum under the action of powerful TE-CO 2 microsecond pulsed laser radiation is initiated on the initial spike or not at all. The minimum “tail” duration to get evaporation was deduced as a function of the temporal pulse shape characteristics and the metal thermophysical properties. The vaporisation process was accompanied by nonequilibrium heating of vapour clouds leading to the target surface shielding. Two self-regulated evolutions were recognised which were attributed to the intense vaporisation and the target evaporation by the UV plasma emitted radiation, respectively.

Periodic structures on the surface of fused silica under multipulse 10.6-μm laser irradiation

Experimental evidence of the formation of periodic structures during multipulse TEA CO2 laser irradiation of fused silica samples is reported. It is shown that the periodic structures formation is determined by the interference between incident and scattered waves, resulting in different values of both the vaporization velocity and the recoil pressure of the vapors back to the interaction surface.

Surface nitridation of zirconium and hafnium by powerful cw CO 2 laser irradiation in air

New experimental results are reported concerning zirconium nitridation and hafnium hardening as a result of power cw CO2 laser irradiation in air.

Plasma-target coupling in the case of TEA-CO2 laser produced breakdown in front of a solid target

Abstract New experimental results concerning the coupling coefficient dependence on geometric conditions, target nature, ambient gas pressure and nature in the case of solid targets irradiation in controlled ambient atmospheres are reported. The data are analysed from the point of view of the relative weight and interference of the proposed mechanisms for energy transfer.

Surface-enhanced Raman scattering observed on chlorinated Cu(111)

Surface-enhanced Raman scattering (SERS) has been observed for the first time on a Cu(111) surface chlorinated in ultra-high vacuum (UHV). The surface obtained preserves its capability to enhance Raman scattering for an indefinitely long time in UHV at sample temperatures Ts<420 K. SERS in this case is shown to be associated with the presence of CuCl on the Cu(111) surface. Enhanced Raman spectra of pyridine adsorbed on chlorinated Cu(111) surface have been obtained.