Remote sensing capability

Luminescence, in particular photoluminescence, constitutes a well-established discipline in analytical science where the cited hallmarks include remarkable sensitivity, wide dynamic range and low detection limits (-10under suitable conditions). These collective merits are often umivaled by other optical techniques, and hence its wide adoption in the life sciences for determining trace constituents in biological and environmental samples. Moreover, its fast response, high spatial resolution and remote sensing capabilities make it attractive for real-time analytical problems such as process manufacturing (process analysis or PAT) and field applications. ... 

In theory, spatially resolved measurements of concentrations of atmospheric trace substances could be made by remote sensing from either surface-based or satellite platforms, but remote sensing capabilities have not yet been developed for many species. Furthermore, both surface- and satellite-based remote sensing methods have distinct limitations in resolving... 

Raman spectroscopy has its main strength in the combination of a fairly high chemical selectivity and a true remote sensing capability. In comparison, NIR has been used extensively in the manufacturing industry due to its ruggedness and simplicity with respect to interfacing of probes to process vessels. However, due to fairly poor spectral selectivity it has to be paired with multivariate data evaluation and is thus sometimes considered as a black box technique. Mid-IR, on the other hand, offers a high selectivity and is also well established... 

Despite the fact that signals from molecules may be coming from thousands of light years away, a quantitative analysis can be performed on interstellar gas through the use of radio telescopes and their remote sensing capabilities. Such telescopes at first glance may seem an odd tool for a chemist, but these instruments basically exploit fundamental principles of molecular spectroscopy in a manner similar, but not identical, to a laboratory spectrometer. 

Over the past few decades, it has become increasingly obvious that interstellar space has a rich and varied chemistry. Quantum mechanics is the basis by which molecules are investigated in space. Rotational spectra obtained from accurate laboratory measurements allow for unambiguous identification of such molecules, combined with the remote-sensing capabilities of radio astronomy. This symbiotic relationship has led to a new chemical field Astrochemistry. 

Fiber optic pH sensors have distinct advantages over pH electrodes. They are small, not interfered by electromagnetic flelds and have remote sensing capability. They can be used in extreme environments, such as deep-water analysis, chemical reactors, or wastewater. Moreover, they can be intrinsically referenced due to the dual wavelength measurement capabiUty and do not require a reference electrode [90]. Optical pH sensors also pave the way for imaging applications, whereas pH electrodes only enable punctiform pH measurements. Sensors for pH determination are also of high significance in environmental and marine research because they provide the basis for CO2 sensors. 

LIBS demonstrated a great capacity for accurate analysis of samples of various compositions, even for in-situ sampling of soils that may exhibit surface dust accumulation. LIBS remote sensing capabilities also make this method an attractive option for a variety of soils analysis and agronomic applications. The ability to obtain immediate results from analyses allows for on-site evaluation of contaminants or pollutants, which can be particularly useful for environmental and... 

Many of the limitations of the above techniques are overcome by optical methods which offer the convenience, accuracy and flexibility to measure curvature through remote sensing capabilities. In this section, several different optical techniques for the measurement of substrate curvature are described, and their advantages and limitations are examined. 

Technology developments are revolutionizing the spectroscopic capabilities at THz frequencies. While no one teclmique is ideal for all applications, both CW and pulsed spectrometers operating at or near the fiindamental limits imposed by quantum mechanics are now within reach. Compact, all-solid-state implementations will soon allow such spectrometers to move out of the laboratory and into a wealth of field and remote-sensing applications. From the study of the rotational motions of light molecules to the large-amplitude vibrations of... 

From a general point of view, a chemical sensor is a device capable of continuously monitoring the concentration of an analyte. The two main classes are electrochemical sensors and optical chemical sensors. The latter are based on the measurement of changes in an optical quantity refractive index, light scattering, reflectance, absorbance, fluorescence, chemiluminescence, etc. For remote sensing, an optical fiber is used, and the optical sensor is then called an optode because of... 

Capability of remote measurements. The small size of the fiber and its electrical, chemical, and thermal inertness allow long-term location of the sensor deep inside complex equipment and thereby provide access to difficult locations where temperature may be of interest. Beyond this, however, certain of the optical techniques allow noncontact or remote sensing of temperature. 

The detection of ocean surface slicks by microwave radars at intermediate incidence angles is well established. The all-weather day-and-night capabilities of microwave remote-sensing has resulted in its wide operational use by harbour authorities for the control of oil pollution in the coastal zone (Attema and Hoogeboom 1978, Sherman 1992). In research, microwave radars can also help further our understanding of air-sea interactions and hydrodynamic processes by providing extensive synoptic two-dimensional maps of the slicks spatial distribution (Espedal et al. 1996, da Silva et al. 1998). 

Since the 1960s natural surface films ( sea slicks ), that tend to exhibit thicknesses of one molecule only, have been in the focus of interdisciplinary research that required input by various disciplines such as oceanography, meteorology, physics and chemistry. Albeit the thickness of such monomolecular surface films is small compared to that of mineral oil films their wave damping capability and, thus, their influence on air-sea interactions is comparable. Consequently, they are still often mixed up with mineral oil films ( oil spills ), particularly in the Same of remote sensing applications. It is the aim of the present book to provide a scientific basis that allows avoiding such misinterpretation in the future. 

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