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Fluid inclusion microthermometry is one of the analytical approaches that has been proposed for speleothem-based temperature reconstructions. The proxy of this paleothermometer is the density of drip water relicts that have been enclosed in microscopic fluid inclusions during speleothem growth. Prior to microthermometric analyses, the monophase liquid inclusions need to be transferred from a metastable liquid into a stable liquid-vapour two-phase state by stimulating vapour bubble nucleation by means of single ultra-short laser pulses. Subsequent microthermometric analyses determine the temperature at which the vapour bubble disappears again, the so-called liquid-vapour homogenisation temperature (Th(obs) ). The observed homogenisation temperature depends not only on the water density but also on the inclusion volume. In order to determine the water density, a thermodynamic model is used that takes account of the effect of surface tension on Th(obs) to calculate Th∞. This is the corresponding homogenisation temperature at saturation pressure that determines the water density and defines the formation temperature of the fluid inclusion. The analytical precision of the method ranges between 0.1 and 0.3 °C depending on the size of the inclusions.
The exciting properties of micro- and nano-patterned surfaces found in natural species hide a virtually endless potential of technological ideas, opening new opportunities for innovation and exploitation in materials science and engineering. Due to the diversity of biomimetic surface functionalities, inspirations from natural surfaces are interesting for a broad range of applications in engineering, including phenomena of adhesion, friction, wear, lubrication, wetting phenomena, self-cleaning, antifouling, antibacterial phenomena, thermoregulation and optics. Lasers are increasingly proving to be promising tools for the precise and controlled structuring of materials at micro- and nano-scales. When ultrashort-pulsed lasers are used, the optimal interplay between laser and material parameters enables structuring down to the nanometer scale. Besides this, a unique aspect of laser processing technology is the possibility for material modifications at multiple (hierarchical) length scales, leading to the complex biomimetic micro- and nano-scale patterns, while adding a new dimension to structure optimization. This article reviews the current state of the art of laser processing methodologies, which are being used for the fabrication of bioinspired artificial surfaces to realize extraordinary wetting, optical, mechanical, and biological-active properties for numerous applications. The innovative aspect of laser functionalized biomimetic surfaces for a wide variety of current and future applications is particularly demonstrated and discussed. The article concludes with illustrating the wealth of arising possibilities and the number of new laser micro/nano fabrication approaches for obtaining complex high-resolution features, which prescribe a future where control of structures and subsequent functionalities are beyond our current imagination.
The possibility to excite surface plasmon polaritons (SPPs) at the interface between two media depends on the optical properties of both media and geometrical aspects. Specific conditions allowing the coupling of light with a plasmon-active interface must be satisfied. Plasmonic effects are well described in noble metals where the imaginary part of the dielectric permittivity is often neglected ('perfect medium approximation (PMA)'). However, some systems exist for which such approximation cannot be applied, hence requiring a refinement of the common SPP theory. In this context, several properties of SPPs such as excitation conditions, period of the electromagnetic field modulation and SPP lifetime then may strongly deviate from that of the PMA. In this paper, calculations taking into account the imaginary part of the dielectric permittivities are presented. The model identifies analytical terms which should not be neglected in the mathematical description of SPPs on lossy materials. These calculations are applied to numerous material combinations resulting in a prediction of the corresponding SPP features. A list of plasmon-active interfaces is provided along with a quantification of the above mentioned SPP properties in the regime where the PMA is not applicable.