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Hyper–Rayleigh Scattering
Hyper–Rayleigh scattering optical activity ( ), a form of chiroptical harmonic scattering, is a nonlinear optical physical effect whereby chiral scatterers (such as nanoparticles or molecules) convert light (or other electromagnetic radiation) to higher frequencies via harmonic generation processes, in a way that the intensity of generated light depends on the chirality of the scatterers. "Hyper–Rayleigh scattering" is a nonlinear optical counterpart to Rayleigh scattering. "Optical activity" refers to any changes in light properties (such as intensity or polarization) that are due to chirality. History The effect was theoretically predicted in 1979, in a mathematical description of hyper Raman scattering optical activity. Within this theoretical model, upon setting the initial and final frequencies of light to the same value, the mathematics describe the hyper Rayleigh scattering optical activity. The theory was well in advance of its time, and the effect remained elusive for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Circular Dichroism
Magnetic circular dichroism (MCD) is the differential absorption of left and right circularly polarized (LCP and RCP) light, induced in a sample by a strong magnetic field oriented parallel to the direction of light propagation. MCD measurements can detect transitions which are too weak to be seen in conventional optical absorption spectra, and it can be used to distinguish between overlapping transitions. Paramagnetic systems are common analytes, as their near-degenerate magnetic sublevels provide strong MCD intensity that varies with both field strength and sample temperature. The MCD signal also provides insight into the symmetry of the electronic levels of the studied systems, such as metal ion sites. History It was first shown by Faraday that optical activity (the Faraday effect) could be induced in matter by a longitudinal magnetic field (a field in the direction of light propagation). The development of MCD really began in the 1930s when a quantum mechanical theory of MOR ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nonlinear Optics
Nonlinear optics (NLO) is the branch of optics that describes the behaviour of light in Nonlinearity, nonlinear media, that is, media in which the polarization density P responds non-linearly to the electric field E of the light. The non-linearity is typically observed only at very high light intensities (when the electric field of the light is >108 V/m and thus comparable to the atomic electric field of ~1011 V/m) such as those provided by lasers. Above the Schwinger limit, the vacuum itself is expected to become nonlinear. In nonlinear optics, the superposition principle no longer holds. History The first nonlinear optical effect to be predicted was two-photon absorption, by Maria Goeppert Mayer for her PhD in 1931, but it remained an unexplored theoretical curiosity until 1961 and the almost simultaneous observation of two-photon absorption at Bell Labs and the discovery of second-harmonic generation by Peter Franken ''et al.'' at University of Michigan, both shortly after th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nature Photonics
''Nature Photonics'' is a peer-reviewed scientific journal published by the Nature Publishing Group. The editor-in-chief is Oliver Graydon. The journal covers research related to optoelectronics, laser science, imaging, communications, and other aspects of photonics and was established in January 2007. ''Nature Photonics'' publishes review articles, research papers, News and Views pieces, and research highlights summarizing the latest scientific findings in optoelectronics. This is complemented by a mix of articles dedicated to the business side of the industry covering areas such as technology commercialization and market analysis. The papers that have been published in this journal are internationally acclaimed for maintaining high research standards. The journal is regarded as top-ranking in the field of photonics. ''Nature Photonics'' is indexed in the NASA Astrophysics Data System and Science Citation Index The Science Citation Index Expanded (SCIE) is a citation index owne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EPSRC
The Engineering and Physical Sciences Research Council (EPSRC) is a British Research Council that provides government funding for grants to undertake research and postgraduate degrees in engineering and the physical sciences, mainly to universities in the United Kingdom. EPSRC research areas include mathematics, physics, chemistry, artificial intelligence and computer science, but exclude particle physics, nuclear physics, space science and astronomy (which fall under the remit of the Science and Technology Facilities Council). Since 2018 it has been part of UK Research and Innovation, which is funded through the Department for Business, Energy and Industrial Strategy. History EPSRC was created in 1994. At first part of the Science and Engineering Research Council (SERC), in 2018 it was one of nine organisations brought together to form UK Research and Innovation (UKRI). Its head office is in Swindon, Wiltshire in the same building (Polaris House) that houses the AHRC, BBS ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Bath
The University of Bath is a public research university in Bath, England. Bath received its royal charter in 1966 as Bath University of Technology, along with a number of other institutions following the Robbins Report. Like the University of Bristol and University of the West of England, Bath can trace its roots to the Merchant Venturers' Technical College, established in Bristol as a school in 1595 by the Society of Merchant Venturers. The university's main campus is located on Claverton Down, a site overlooking the UNESCO World Heritage city of Bath, and was purpose-built, constructed from 1964 in the modernist style of the times. In the 2021 Research Excellence Framework, 40% of Bath's submitted research activity achieved the highest possible classification of 4*, defined as world-leading in terms of originality, significance and rigour. 92% was graded 4*/3*, defined as world-leading/internationally excellent. The annual income of the institution for 2023–24 was � ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vibrational Circular Dichroism
Vibrational circular dichroism (VCD) is a spectroscopic technique which detects differences in attenuation of left and right circularly polarized light passing through a sample. It is the extension of circular dichroism spectroscopy into the infrared and near infrared ranges. Because VCD is sensitive to the mutual orientation of distinct groups in a molecule, it provides three-dimensional structural information. Thus, it is a powerful technique as VCD spectra of enantiomers can be simulated using ''ab initio'' calculations, thereby allowing the identification of absolute configurations of small molecules in solution from VCD spectra. Among such quantum computations of VCD spectra resulting from the chiral properties of small organic molecules are those based on density functional theory (DFT) and gauge-including atomic orbitals (GIAO). As a simple example of the experimental results that were obtained by VCD are the spectral data obtained within the carbon-hydrogen (C-H) stretching ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two-photon Circular Dichroism
Two-photon circular dichroism (TPCD), the nonlinear counterpart of Circular dichroism, electronic circular dichroism (ECD), is defined as the differences between the Two-photon absorption, two-photon absorption (TPA) cross-sections obtained using left circular polarized light and right circular polarized light (see Figure 1). Background Typically, two-photon absorption (TPA) takes place at twice the wavelength as one-photon absorption (OPA). This feature allows for the TPCD based study of Chirality, chiral systems in the far to near ultraviolet (UV) region. ECD cannot be employed in this region due to interferences from strong linear absorption of typical buffers and solvents and also because of the scattering exhibited by inhomogeneous samples in this region. Several other advantages are associated with the use of non-linear absorption, i.e. high spatial resolution, enhanced penetration depth, improved background discrimination and reduced photodamage to living specimens. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raman Optical Activity
Raman optical activity (ROA) is a vibrational spectroscopic technique that is reliant on the difference in intensity of Raman scattered right and left circularly polarised light due to molecular chirality. History of Raman optical activity The field began with the doctoral work of Laurence D. Barron with Peter Atkins at the University of Oxford and was later further developed by Barron with David Buckingham at the University of Cambridge. More developments, including important contributions to the development of practical Raman optical activity instruments, were made by Werner Hug of the University of Fribourg, and Lutz Hecht with Laurence Barron at the University of Glasgow. Theory of Raman optical activity The basic principle of Raman optical activity is that there is interference between light waves scattered by the polarizability and optical activity tensors of a chiral molecule, which leads to a difference between the intensities of the right- and left-handed circula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Rotatory Dispersion
In optics, optical rotatory dispersion is the variation of the specific rotation of a medium with respect to the wavelength of light. Usually described by German physicist Paul Drude's empirical relation: alpha\lambda^T=\sum_^\infty\frac where alpha\lambda^T is the specific rotation at temperature T and wavelength \lambda, and A_n and \lambda_n are constants that depend on the properties of the medium. Optical rotatory dispersion has applications in organic chemistry regarding determining the structure of organic compounds. Principles of operation When white light passes through a polarizer, the extent of rotation of light depends on its wavelength. Short wavelengths are rotated more than longer wavelengths, per unit of distance. Because the wavelength of light determines its color, the variation of color with distance through the tube is observed. This dependence of specific rotation on wavelength is called optical rotatory dispersion. In all materials the rotation va ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Rotation
Optical rotation, also known as polarization rotation or circular birefringence, is the rotation of the orientation of the plane of polarization about the optical axis of linearly polarized light as it travels through certain materials. Circular birefringence and circular dichroism are the manifestations of optical activity. Optical activity occurs only in chiral materials, those lacking microscopic mirror symmetry. Unlike other sources of birefringence which alter a beam's state of polarization, optical activity can be observed in fluids. This can include gases or solutions of chiral molecules such as sugars, molecules with helical secondary structure such as some proteins, and also chiral liquid crystals. It can also be observed in chiral solids such as certain crystals with a rotation between adjacent crystal planes (such as quartz) or metamaterials. When looking at the source of light, the rotation of the plane of polarization may be either to the right (dextrorotatory ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
