V. V. Lisitsa

Determination of iron in water solution by time-resolved femtosecond laser-induced breakdown spectroscopy

The influence of the energy of femtosecond laser pulses on the intensity of Fe I (371.99 nm) emission line and the continuous spectrum of the plasma generated on the surface of Fe3+ water solution by a Ti: sapphire laser radiation with pulse duration < 45 fs and energies up to 7 mJ is determined. A calibration curve was obtained for Fe3+ concentration range from 0.5 g/L to the limit of detection in water solution, and its saturation was detected for concentrations above 0.25 g/L, which is ascribed to self-absorption. The 3σ- limit of detection obtained for Fe in water solution is 2.6 mg/L in the case of 7 mJ laser pulse energy. It is found that an increase of laser pulse energy insignificantly affects on LOD in the time-resolved LIBS and leads to a slight improvement of the limit of detection.

Influence of energy and repetition rate of the femtosecond laser pulses on the spectral and temporal characteristics of plasma in laser induced breakdown spectroscopy of aqueous solutions

Experimentally determined the influence of energy and pulse repetition rate of the femtosecond Ti: sapphire laser on the intensity of the spectral lines in the optical breakdown on the surface of an aqueous solution of CaCl2 and aqueous solutions of iron. The time dependence of the intensity of the continuous and line spectra of the plasma was obtained from the laser pulse energy. It is shown that by increasing the laser pulse repetition frequency from 20 Hz to 1000 Hz is observed up to 45% reduction of the emission line intensity Ca II (393.3 nm).

Influence of laser pulse energy on emission lines intensity in the femtosecond laser-induced breakdown spectroscopy of iron in aqua solution

The influence of pulse energy on the time evolution of the intensity of the continuum and emission lines of plasma generated on the surface of aqueous solutions of iron by focused radiation Ti: sapphire laser with a wavelength of 800 nm and pulse duration of 45 fs and a range of energy 3-7 mJ was investigated. The calibration curve for iron in water and 3-ó limit of detection of iron in water was obtained.

Spectral and temporal characteristics of hydrogen emission during femtosecond optical breakdown on a water surface

Spectral and time characteristics of a hydrogen HI 656 nm emission line are experimentally investigated during optical breakdown generated by pulses of the first harmonics of a femtosecond Ti:Sapphire laser on the water surface. The electron density of the generated plasma is estimated.

Spectral and temporal characteristics of Ba I emission in femtosecond laser-induced breakdown on the surfaces of aqueous solutions

Temporal behavior of the intensity of Ba I emission lines (413.24 and 553.55 nm) in plasma of optical breakdown induced by femtosecond laser pulses (800 nm, 45 fs, 0.82 mJ) on the surface of BaCl2 aqueous solution was experimentally studied as dependent on delay time td relative to the breakdown onset. The maximum intensity of the Ba I (413.24 nm) line was observed at td = 20 ns, while the intensity of the Ba I (553.55 nm) line reached a maximum at td = 40 ns. At td = 10 ns, the intensity of the Ba I (413.24 nm) line was almost three times as large as that of Ba I (553.55 nm) line (despite the about two orders of magnitude lower probability of spontaneous transition for the former line), which is explained by the recombination cascade. It is established that, in the subsystem of 5d6p3D0 and 6s6p1P0 levels, the Boltzmann distribution is not valid and the local thermodynamic equilibrium is absent.

Development and creation of a remote-controlled underwater laser induced breakdown spectrometer for analysis of the chemical composition of sea water and bottom sediments

The developed underwater laser induced breakdown spectrometer consists of two units: 1- remotely operated vehicle (ROV) with the next main characteristics: work deep – up to 150 meters, maximum speed of immersion 1 m/s, maximum cruise velocity - 2 m/s and 2 – spectrometer unit (SU) consist of a DPSS Nd: YAG laser excitation source (double pulse with 50 mJ energy for each pulse at wavelength 1064 nm, pulse width 12 ns and pulse repetition rate 1-15 Hz, DF251, SOL Instruments), a spectrum recording system (Maya HR4000 or 2000 Pro spectrometer, Ocean Optics) and microcomputer. These two units are connected by Ethernet network and registered spectral data are automatically processed in a MATLAB platform.

Investigation of laser plasma temperature and spectral line broadening in femtosecond laser plasma on the surface of barium water solution

The spectral lines broadening in femtosecond laser plasma generated by the 45 fs Ti:Sa laser pulses on the surface of the water solutions of Ba is investigated. The contribution of the Doppler broadening for spectral lines width is minimal and amounts 0.0022 nm for Ba. The main mechanism of Ba spectral line broadening in experimental conditions is resonance. The resulting values of resonance broadening constitute a 0.0349 nm for Ba I (413.24 nm), 0.0563 nm for Ba I (553.54 nm), 0.0241 nm for Ba II (455.41 nm), 0.0437 nm for Ba II (614.17 nm).

Lidar sensing atmosphere by gigawatt femtosecond laser pulses in the continent-ocean transition zone

Created three modifications lidar systems based on Ti: sapphire laser with chirped power amplification (elastic scattering lidar, Raman lidar, white light lidar) and derived atmospheric lidar sensing data in a transition zone continent-ocean. Comparisons of the data with the results of conventional lidar based on the use of nanosecond laser pulses are presented. Possibilities and prospects created by femtosecond lidar modifications in the conditions of the transition zone continentocean.

Femtosecond Ti:Sa Laser Processing of Silica

The result of direct ablation of silicon by an 800 nm Ti:Sa femtosecond laser pulses are presented. Obtained slice of silicon with submicron roughness with tilt focused femtosecond laser pulses. Yaw cut more due to mechanical vibrations of the entire installation on a pneumatic table, but not the physics of the ongoing process. During processing, possibly thinning the silicon sample from the opposite edge (sharpening) to submicron values (tens of nanometers).