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Development and applications of nonlinear optical spectroscopy: 14th ECONOS/34th ECW meeting in Leuven (Belgium)

2016; Wiley; Volume: 47; Issue: 9 Linguagem: Inglês

10.1002/jrs.4962

1097-4555

Johan Hofkens, Maarten B. J. Roeffaers, Johannes Kiefer, Julian Moger,

Protein Interaction Studies and Fluorescence Analysis

The joint conference of the European Conference on Nonlinear Optical Spectroscopy (ECONOS) and European CARS Workshop (ECW) covers all theoretical and experimental aspects of nonlinear optical spectroscopy and microscopy. Topics include Coherent anti-Stokes Raman scattering (CARS) spectroscopy and microscopy, and other forms of coherent Raman scattering, other approaches to the detection of nonlinear optical responses in time and frequency domain, and investigations of the physical and chemical processes defining the spectral signatures in different nonlinear media. Also, emerging analytical techniques and their applications in biomedical research, material science, and engineering are discussed. The 14th ECONOS conference and 34th CARS workshop were held in Leuven, Belgium, on 12–15 April 2015, chaired by Johan Hofkens and Maarten Roeffaers (KU Leuven). Altogether, 75 participants shared their research in oral sessions and poster sessions and participated in lively discussions and social activities. After an invited lecture and a welcome reception in the historic Promotion Hall of KU Leuven on Sunday, the regular scientific program began on Monday morning at the same place. Six invited talks were given during the course of the conference, followed by contributed oral presentations, and two poster sessions. This special section of the Journal of Raman Spectroscopy constitutes a selection of eight papers presented at ECONOS/ECW 2015. Moreover, this section is part of the special issue in honour of Wolfgang Kiefer on the occasion of his 75th birthday. Wolfgang Kiefer has been an active member of the ECONOS/ECW community, and he was the editor-in-chief of the Journal of Raman Spectroscopy, who established the annual special issue. Therefore, the organizers of ECONOS 2015 and the JRS guest editors are more than happy that this year's special section is included in this particular special issue. Due to the broad scope of the conference, the papers cover a broad range of methods and their applications to a variety of systems. The special section starts with a review paper authored by all the guest editors of ECONOS issues since 2002.1 It covers all the contributions that have been published since and puts them into a wider context. From the analysis of the science presented in the papers, the continuous developments can be clearly seen. A statistical analysis showed the geographical distribution of the papers and, moreover, that four main topical categories can be identified: (1) theoretical and instrumental developments, (2) applications to gas-phase and combustion systems, (3) applications to condensed phase matter, and (4) development and applications of micro-spectroscopy methods. We hope that you will enjoy reading this comprehensive overview. The majority of original research papers are concerned with nonlinear optical spectroscopy in gas-phase systems. Visser et al.2 investigated the potential of using two-color resonant and degenerate four-wave mixing spectroscopy to study transition metal dimers. For this purpose, a new laser vaporization source was developed to produce metal dimers and larger clusters in a reproducible manner. Test measurements were carried out with Cu2, and a comparison between the nonlinear techniques and the conventional laser-induced fluorescence and cavity ring-down spectroscopy was performed. Stauffer et al.3 report the collision-independent detection of gas-phase nitric oxide (NO) via two-pulse, femtosecond time-resolved parametric four-wave-mixing. They exploit two-photon broadband excitation of rovibronic manifolds, allowing species-specific detection with negligible dependence on colliding-partner concentrations at short (<10 ps) time delays. Their approach works even in the presence of species that strongly quench excited-state fluorescence. Sahlberg et al.4 analysed the potential of infrared degenerate four-wave mixing as a tool for non-intrusive spatially resolved detection of four small hydrocarbons (methane, acetylene, ethylene, and ethane) in combustion environments. Excitation scans probed rovibrational transitions belonging to the fundamental CH stretching modes around 3 µm. The hydrocarbons were studied in gases flows, in which they were diluted in nitrogen at atmospheric pressure and elevated temperatures up to 820 K. Sahlberg et al.5 also developed infrared degenerate four-wave mixing as a tool for the detection of ammonia in various buffer gases. For this purpose, rovibrational transitions belonging to combination bands around 2.3 µm were probed at atmospheric pressure and elevated temperatures. At ambient conditions, a detection limit of ~550 ppm was found. A turbulent oxy-fuel flame was studied by Tröger et al.6 using vibrational coherent anti-Stokes Raman spectroscopy of molecular oxygen. They performed temporally and spatially resolved temperature measurements in a challenging large-scale combustion process that was used to heat an industrial glass melt. Modifications in the exhaust system of the furnace led to systematic changes in the temperature distribution and statistics. Hell et al.7 applied laser-induced thermal acoustics to investigate another challenging object, that is, the supersonic combustion of hydrogen. In their paper, two validation cases for laser-induced thermal acoustics measurements are presented together with first measurements in a chemically reacting free jet, where hydrogen is injected in a supersonic air co-flow. The validation cases include the study of premixed flat flames and supersonic, hot air/air free jets. A development in the area of nonlinear microscopy was demonstrated by Karuna et al.8 Their work focused on the analysis of images from hyperspectral coherent anti-Stokes Raman scattering microscopy, which is a fundamental tool in cell biology due to the ability to map the concentration of the endogenous molecules in cells with superior chemical specificity. Their method allows the quantitative determination of the absolute volumes of chemical components in three-dimensional imaging. Additionally, they discussed the use of sodium chloride as a standard non-resonant reference material for CARS as a possible alternative to the commonly used glass. This ECONOS/ECW special issue highlights the continuous progress in the area of nonlinear optical spectroscopy and its applications across the science and engineering disciplines. The enthusiasm and creativity of the scientific community as well as the rapid development of novel and improved experimental equipment will ensure an exciting future of nonlinear spectroscopy research. We would like to thank all the delegates, presenters of talks and posters, helpers in the background, and sponsors, who made the 2015 ECONOS/ECW meeting in Belgium an enjoyable and memorable event. Special thanks to the Editor-in-Chief of the Journal of Raman Spectroscopy, Larry Nafie, for making this special issue possible, and of course, to all the authors and reviewers of the papers for their invaluable contribution.