Review Article Multiphoton Ionization and Fragmentation of Hydrogen Chloride: A Diatomic Still Good for a Surprise

The competition between multiphoton ionization and fragmentation in the diatomic molecule hydrogen chloride is reviewed. Emphasis is laid on recent experimental results employing chemical imaging methods in order to obtain kinetic energy distributions and angular distributions of photoproducts. The energy range considered is 15 to 20 eV, equivalent to the absorption of three or four photons in the ultraviolet wavelength range. The role of Rydberg states as resonantly excited intermediate states in the ionization/fragmentation processes is assessed. Mixing among 1 Σ + states gives rise to peculiarly shaped double minimum potential energy curves which allow for the production of hydrogen and chlorine atomic and ionic fragments via several competing pathways, in addition to the production of molecular HCl + ions. States with different electronic properties show a qualitatively different behaviour from Σ + states. Accidental resonances between states of differing orbital angular momentum or multiplicity serve to override these differences and cause subtle as well as significant deviations from the unperturbed behaviour

Powerful low-frequency vibrators and outlooks of their application at monitoring of engineering constructions and at solving other problems of active seismology

In the past two decades, active seismology studies in Russia have made use of powerful (40- and 100-ton) low-frequency vibrators. These sources create a force amplitude of up to 100 tons and function in the 1.5-3, 3-6 and 5-10 Hz frequency bands. The mobile versions of the vibrator have a force amplitude of 40 tons and a 6-12 Hz frequency band. Registration distances for the 100 ton vibrator are as large as 350 km, enabling the refracted waves to penetrate down to 50 km depths. Vibrator operation sessions are highly repeatable, having distinct "summer" or "winter" spectral patterns. A long profile of seismic records allows estimating of fault zone depths using changes in recorded spectra. Other applications include deep seismic profiling, seismic hazard mapping, structural testing, stress induced anisotropy studies, seismic station calibration, and large-structure integrity testing. In more detail, these questions are discussed in reports of our colleagues from Novosibirsk. This report is devoted mainly to powerful low-frequency vibrators, their theoretical description and design. Besides, problems of vibroseismic monitoring of engineering constructions are briefly elucidated