Spectrochimica Acta Part B 57 (2002) 591–599 0584-8547/02/$ - see front matter  2002 Elsevier Science B.V. All rights reserved. PII: S0584-8547 Ž 01 . 00388-3 Open-path laser-induced plasma spectrometry for remote analytical measurements on solid surfaces  S. Palanco , J.M. Baena , J.J. Laserna * a b a, Department of Analytical Chemistry, Faculty of Sciences, University of Malaga, E-29071 Malaga, Spain a ´ ´ Acerinox S.A., P.O. Box 83, E-11370 Los Barrios, Spain b Received 10 September 2001; accepted 20 November 2001 Abstract Open-path laser-induced plasma spectrometry has been studied for elemental analysis at a distance of 45 m from the target. The 230-mJ pulsed radiation of a Q-switched Nd:YAG laser at 1064 nm has been used to produce a plasma on the sample and light emission has been collected under an off-axis open-path scheme. Under such conditions, the main variables influencing the signal response such as beam focal conditions, laser incidence angle and laser penetration depth have been identified and diagnosed on the basis of spectral signal-to-noise ratio considerations. The incidence angle is critical beyond 608. Crater morphology and ablation rates have been studied also. A semi-quantitative analysis of several stainless steel grades has been implemented using a pattern recognition algorithm, which allowed to discriminate successfully the samples on the basis of their variable content in alloying elements.  2002 Elsevier Science B.V. All rights reserved. Keywords: Remote analysis; Steel; Laser-induced plasma; Atomic emission spectrometry 1. Introduction Optical remote sensing techniques provide the capability to remotely monitor and measure trace gases and aerosols by guiding a laser beam either across a large open atmospheric path (direct sens- ing) or through fiber optics (indirect sensing) towards the sample of interest w1–4x. Although the  This paper was presented at Colloquium Spectroscopicum Internationale XXXII, held in Pretoria, South Africa, 8–13 July 2001 and is published in the special issue of Spectrochim- ica Acta Part B, dedicated to that conference. *Corresponding author. Tel.: q34-95-213-1881; fax: q34- 95-213-2000. E-mail address: laserna@uma.es (J.J. Laserna). fiber approach indeed makes possible the analysis at remote places which are unreachable by other means, indirect sensing is of restricted application in those cases where aggressive chemical or tem- perature environments may affect the condition of the probe, or when large areas must be analyzed. In such cases, the open path approach is more suitable as it is demonstrated by a wide range of applications covering environment monitoring in atmospheric w5,6x, ocean w7,8x and ground media w9,10x, large-field area mapping w11,12x, agricul- tural purposes w13,14x, and cultural-heritage con- servation w15,16x, among many others. This wide applicability is feasible due to the fact that the