Vibrational Microspectroscopic Imaging Spatial Resolution Enhancement

We propose a methodology for enhancing the diffraction limited spatial resolution attained in Raman and Fourier transform infrared microspectroscopic imaging techniques. Near-field scanning optical microscopy (SNOM) and spectroscopy employ apertureless and aperture approaches to provide ultra-high spatially resolved images at the nanometer level. In contrast, we employ conventional spectral acquisition schemes modified by spatial oversampling with the subsequent application of deconvolution techniques. As an example, this methodology is applied to flat samples using point illumination. Simulated data, assuming idealized sample concentration profiles, are presented together with experimental Raman microspectroscopic data from chemically and morphologically well-defined test samples. Intensity profiles determined using conventional mapping and imaging techniques are compared to those obtained by the probe/deconvolution methodology.

Raman imaging has long been used to probe the chemical nature of a sample, providing information on molecular orientation, symmetry and structure with sub-micron spatial resolution. Recent technical developments have pushed the limits of micro-Raman microscopy, enabling the acquisition of Raman spectra with unprecedented speed, and opening a pathway to fast chemical imaging for many applications from material science and semiconductors to pharmaceutical drug development and cell biology, and even art and forensic science. The promise of tip-enhanced raman spectroscopy (TERS) and near-field techniques is pushing the envelope even further by breaking the limit of diffraction and enabling nano-Raman microscopy.

Bringing several disparate aspects of food science and analysis together in one place, Applications of Vibrational Spectroscopy to Food Science provides a comprehensive, state-of the-art text presenting the fundamentals of the methodology, as well as underlying current areas of research in food science analysis. All of the major spectroscopic techniques are also covered – showing how each one can be used beneficially and in a complementary approach for certain applications. Case studies illustrate the many applications in vibrational spectroscopy to the analysis of foodstuffs.

Modern Vibrational Spectroscopy and Micro-Spectroscopy: Theory, Instrumentation and Biomedical Applications unites the theory and background of conventional vibrational spectroscopy with the principles of microspectroscopy. It starts with basic theory as it applies to small molecules and then expands it to include the large biomolecules which are the main topic of the book with an emphasis on practical experiments, results analysis and medical and diagnostic applications. This book is unique in that it addresses both the parent spectroscopy and the microspectroscopic aspects in one volume. Part I covers the basic theory, principles and instrumentation of classical vibrational, infrared and Raman spectroscopy. It is aimed at researchers with a background in chemistry and physics, and is presented at the level suitable for first year graduate students. The latter half of Part I is devoted to more novel subjects in vibrational spectroscopy, such as resonance and non-linear Raman effects, vibrational optical activity, time resolved spectroscopy and computational methods. Thus, Part 1 represents a short course into modern vibrational spectroscopy. Part II is devoted in its entirety to applications of vibrational spectroscopic techniques to biophysical and bio-structural research, and the more recent extension of vibrational spectroscopy to microscopic data acquisition. Vibrational microscopy (or microspectroscopy) has opened entirely new avenues toward applications in the biomedical sciences, and has created new research fields collectively referred to as Spectral Cytopathology (SCP) and Spectral Histopathology (SHP). In order to fully exploit the information contained in the micro-spectral datasets, methods of multivariate analysis need to be employed. These methods, along with representative results of both SCP and SHP are presented and discussed in detail in Part II.

This second edition of the successful ready reference is updated and revised with approximately 30% new content to reflect the numerous instrumental developments and improvements, as well as the significant expansion of this rapidly developing field. For example, the combination of IR imaging with AFM has enhanced the achievable lateral resolution by an order of magnitude down to a few hundred nanometers, thus launching a multiplicity of new applications in material science. Furthermore, Raman and IR spectroscopic imaging have become key technologies for the life sciences and today contribute tremendously to a better and more detailed understanding of numerous biological and medical research topics. The topical structure of this new edition is now subdivided into four parts. The first treats the fundamentals of the instrumentation for infrared and Raman imaging and mapping and an overview on the chemometric tools for image analysis. The second part describes a wide varie-ty of applications ranging from biomedical via food, agriculture and plants to polymers and pharmaceuticals. This is followed by a description of imaging techniques operating beyond the diffraction limit, while the final part covers special methodical developments and their utility in specific fields. With its many valuable practical tips, this is a must-have overview for researchers in academic and industrial laboratories wishing to obtain reliable results with this method.

Molecular and Laser Spectroscopy, Advances and Applications: Volume 2 gives students and researchers an up-to-date understanding of the fast-developing area of molecular and laser spectroscopy. This book covers basic principles and advances in several conventional as well as new and upcoming areas of molecular and laser spectroscopy, such as a wide range of applications in medical science, material science, standoff detection, defence and security, chemicals and pharmaceuticals, and environmental science. It covers the latest advancements, both in terms of techniques and applications, and highlights future projections. Editors V.P. Gupta and Yukihiro Ozaki have brought together eminent scientists in different areas of spectroscopy to develop specialized topics in conventional molecular spectroscopy (Cavity ringdown, Matrix Isolation, Intense THz, Far- and Deep- UV, Optogalvanic ), linear and nonlinear laser spectroscopy (Rayleigh & Raman Scattering), Ultrafast Time-resolved spectroscopy, and medical applications of molecular spectroscopy. and advanced material found in research articles. This new volume expands upon the topics covered in the first volume for scientists to learn the latest techniques and put them to practical use in their work. Covers several areas of spectroscopy research and expands upon topics covered in the first volume Includes exhaustive lists of research articles, reviews, and books at the end of each chapter to further learning objectives Uses illustrative examples of the varied applications to provide a practical guide to those interested in using molecular and laser spectroscopy tools in their research

Abstract : Much research effort has been spent in the 21st century on superresolution imaging techniques, methods which can beat the diffraction limit. Subwavelength composite structures called ``metamaterials" had initially shown great promise in superresolution imaging applications in the early 2000s, owing to their potential for nearly arbitrary capabilities in controlling light. However, for optical frequencies they are often plagued by absorption and scattering losses which can decay or destroy their interesting properties. Similar issues limit the application of other superresolution devices operating as effective media, or metal films that can transfer waves with large momentum by supporting surface plasmon polaritons. In this dissertation, new methods of mitigating the loss of object information in lossy and noisy optical imaging systems are presented. The result is an improvement in the upper bound on lateral spatial resolution. A concentration is placed on metamaterial and plasmonic imaging systems, and the same methods are subsequently adapted to more conventional far-field imaging systems. First, through numerical simulation it is shown that a lossy metamaterial lens has degraded imaging performance which can be partially compensated by deconvolution post-processing of the resultant image. This post-processing procedure is then shown to emulate a physical process called plasmon injection, which has been previously implemented to effectively remove the losses in a plasmonic metamaterial. Next, a more realistic scenario is considered; a thin film of silver acting as a near-field plasmonic ``superlens." In this case, methods are implemented to model incoherent light propagation so that the image can be reconstructed using only intensity data, removing the need for phase measurement. The same procedure from above is followed, and the resolution is enhanced. To push the resolution further, a spatial filtering method called active convolved illumination is developed to overcome the resolution limit set by the noise floor of the system. Finally, the spatial filtering methods are applied to more a more conventional far-field imaging system. Supported by experiment, the lateral resolution of a low numerical aperture imaging system is improved by blocking photons at the Fourier plane. For coherent light, a diffractive superlens is designed which uses the same principles from the above theory, except it encodes the high spatial frequency waves into propagating waves via a diffraction grating. The result is lateral resolution performance that surpasses similar previously published devices by 10 nm at a wavelength more than 80 nm longer.

An all-inclusive guide on the analytical methods of Raman, infrared, and near-infrared chemical imaging An underutilized technology, chemical imaging through Raman, infrared (IR), and near-infrared (NIR) is beginning to gain recognition for its non-destructive method of permitting visualization of spatially resolved chemical information. This type of analysis is triggering a groundswell of demand as manufactured materials become more complex and the need for greater scrutiny and less damaging research practices is at a premium. Concentrating on the applications of chemical imaging, this book presents a thorough background on the theory, software, and hardware employed in this analytical technique. With full examination of this rapidly growing field, this book: Combines many different aspects and applications into one comprehensive volume Discusses how chemical imaging techniques have expanded greatly in terms of instruments and applications, but have lagged in general awareness among scientists and industries that would benefit the most from them Describes chemical imaging uses in key areas—biomedical, pharmaceutical, food, and polymer research Has chapters that outline hardware and instrumentation for the different methods of chemical imaging Encapsulating analytic methods without complicating the subject matter, this book shows where chemical imaging has been successfully applied, inspiring researchers to cultivate the exciting capabilities rooted within this powerful and multifaceted technology.

This comprehensive overview of biomedical applications of vibrational spectroscopy focuses on methodologies that are most relevant to biodiagnostics. After a few introductory chapters that summarize the current status of the field, the reference covers current spectroscopic applications; new spectroscopic directions; and study design and the analysis of vibrational spectral fingerprints from complex biological and clinical samples . With chapters contributed by leading international experts, Biomedical Vibrational Spectroscopy is a core resource.

In recent years there has been a tremendous growth in the use of vibrational spectroscopic methods for diagnosis and screening. These applications range from diagnosis of disease states in humans, such as cancer, to rapid identification and screening of microorganisms. The growth in such types of studies has been possible thanks to advances in instrumentation and associated computational and mathematical tools for data processing and analysis. This volume of Advances in Biomedical Spectroscopy contains chapters from leading experts who discuss the latest advances in the application of Fourier transform infrared (FTIR), Near infrared (NIR), Terahertz and Raman spectroscopy for diagnosis and screening in fields ranging from medicine, dentistry, forensics and aquatic science. Many of the chapters provide information on sample preparation, data acquisition and data interpretation that would be particularly valuable for new users of these techniques including established scientists and graduate students in both academia and industry.