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Plasma plume expansion and crater formation in the interaction of Nd -YAG laser beam (TEM oo - mode, 532 nm, 6 ns pulse duration and 10 μm waist at FWHM) with various metal targets in air were investigated. The craters formed at the surfaces were measured with 0,1 μm longitudinal and 0,5 μm transversal resolutions. Laser plasma expansion during laser pulse / surface interaction was measured by ICCD camera with 3 μm spatial and I ns temporal resolutions. These measurements were performed with different optical filters in the following spectral ranges (250< λ

Laser ablation of pure metals by femtosecond, picosecond and nanosecond pulses is studied experimentally in air at atmospheric pressure. Craters created by interaction of visible and UV laser pulses with the targets are investigated. The dependence of the ablation efficiency in terms of ablated volume per unit of energy on the pulse duration and wavelength is discussed.

We have investigated the craters created after high intensity visible and UV-laser pulse interaction with the metalsurfaces in air. The experiments were performed on different pure metal samples in the intensity range typical for laserplasma analytical application experiments with nanosecond laser pulses. The craters were characterised by their depth,diameter and volume. The analysis and discussion ofthe obtained results are presented.Keywords: laser ablation, metal samples, spectrochemical analysis, ablation efficiency.I. INTRODUCTION.High intensity laser pulse interaction with a solid surface leads to crater formation resulting from matter ejection. Asthe ablation process depends on physical properties of solid matter, environmental conditions and laser parameters , the description of crater characteristics is seen as an interesting method to understand the physics of the ablation process.In this work, the crater was characterised by its depth, diameter and volume (Fig. 1).The experiments were performed on different metal samples with a large variety of matter properties. Laser intensitieswere chosen from 0.5

Laser ablation of pure metals by femtosecond, picosecond and nanosecond pulses is studied in air at atmospheric pressure. Craters created after interaction of visible and UV laser pulses with the targets are investigated. The dependence of the ablation efficiency in terms of ablated volume per unit of energy on the pulse duration is discussed.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Time-Resolved Laser-Induced Fluorescence (TRLIF) is a very sensitive and selective method that has been used for actinides and lanthanides analysis in the nuclear fuel cycle. This technique has been used in different fields such as in geology, in the Purex process, in the environment, in the medical and in waste storage assessment. Spectroscopic data, limits of detection and results obtained in previously quoted fields are presented.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Time-Resolved Laser-Induced Fluorescence has been used for uranium and nitrate remote sensing in the nuclear fuel cycle. Advantages of this technique are aside sensitivity and selectivity, its ability to perform remote measurements via fiber optics and optode. Uranium is usually determined by the standard addition method but by applying a fluorescence model taking into account complexation and absorption phenomena, it is possible to directly determine uranium concentration. Nitrate concentration is determined after spectral deconvolution of the uranium fluorescence spectrum.

Direct analysis of solid materials without sample digestion are requirement in analytical plasma emission spectrometry. Laser ablation permits the production of fine particles to be atomized, excited and ionized in a secondary source such as an inductively coupled plasma. Laser characteristics such as the pulse duration, the beam shape and the wavelength seem to play a significant role in the shape of the crater and the amount of ablated material. A Nd:YAG laser at 1064, 532 and 355 nm has been compared with a XeCl laser at 308 nm. Using the various lasers, crater shapes are described and amounts of ablated material are compared.